BULLETIN A NEW SPECIES OF TELEOCERAS (MAMMALIA, RHINOCEROTIDAE) FROM THE LATE HEMPHILLIAN OF TENNESSEE Rachel A. Short, Steven C. Wallace, and Laura G. Emmert Vol. 56, No. 5, pp. 183–260 April 27, 2019 ISSN 2373-9991 UNIVERSITY OF FLORIDA GAINESVILLE The FLORIDA MUSEUM OF NATURAL HISTORY is Florida’s state museum of natural history, dedicated to understanding, preserving, and interpreting biological diversity and cultural heritage. The BULLETIN OF THE FLORIDA MUSEUM OF NATURAL HISTORY is an on-line, open-ac- cess, peer-reviewed journal that publishes results of original research in zoology, botany, paleontology, archaeology, and museum science. New issues of the Bulletin are published at irregular intervals, and volumes are not necessarily completed in any one year. Volumes contain between 150 and 300 pages, sometimes more. The number of papers contained in each volume varies, depending upon the number of pages in each paper, but four numbers is the current standard. Multi-author issues of related papers have been published together, and inquiries about putting together such isues are welcomed. Address all inqui- ries to the Editor of the Bulletin. The electronic edition of this article conforms to the requirements of the amended International Code of Zoological Nomenclature, and hence the new names contained herein are available under that Code. This published work and the nomenclatural acts it contains have been registered in ZooBank, the online regis- tration system for the ICZN. The ZooBank Publication number for this issue is B925B0D2-740E-440A- AB1A-0D480B9C963D. Richard C. Hulbert Jr., Editor Bulletin Committee Richard C. Hulbert Jr. Jacqueline Miller Larry M. Page David W. Steadman Roger W. Portell, Treasurer Jonathan I. Bloch, Ex officio Member ISSN: 2373-9991 Copyright © 2019 by the Florida Museum of Natural History, University of Florida. All rights reserved. Text, images and other media are for nonprofit, educational, and personal use of students, scholars, and the public. Any commercial use or republication by printed or electronic media is strictly prohibited without written permission of the museum. Publication Date: April 27, 2019. This number concludes volume 56. This and other recent issues of the Bulletin can be freely downloaded at: https://www.floridamuseum.ufl.edu/bulletin/publications/ Send communications about this publication to: Editor of the Bulletin; Florida Museum of Natural History; University of Florida; P.O. Box 117800; Gainesville, FL 32611-7800 USA FAX: 352-846-0287; Email: bulletin@flmnh.ufl.edu URL: https://www.floridamuseum.ufl.edu/bulletin/home/ http://zoobank.org/ mailto:bulletin@flmnh.ufl.edu A NEW SPECIES OF TELEOCERAS (MAMMALIA, RHINOCEROTIDAE) FROM THE LATE HEMPHILLIAN OF TENNESSEE Rachel A. Short1,2, Steven C. Wallace2,3, and Laura G. Emmert2 1Department of Ecosystem Science and Management, Texas A&M University, College Station, Texas 77843, USA 2Don Sundquist Center of Excellence in Paleontology, East Tennessee State University Museum of Natural History, Gray, Tennessee 37615, USA , 3Department of Geosciences, East Tennessee State University, Johnson City, Tennessee 37614, USA Short, R. A., S. C. Wallace, and L. G. Emmert. 2019. A new species of Teleoceras (Mammalia, Rhinocerotidae) from the late Hemphillian of Tennessee. Bulletin of the Florida Museum of Natural History 56(5):183–260. ABSTRACT A new species of rhinoceros, Teleoceras aepysoma n. sp., is described from the late Hemphillian-aged Gray Fossil Site of eastern Tennessee. Fossils from a minimum of six individuals, including two nearly complete, articulated skeletons, have been found at the Gray Fossil Site. Availability of such complete specimens enables a thorough morphological description of the new species. Furthermore, the diagnostic characters of T. aepysoma necessitate an emended diagnosis for the tribe Teleoceratini and genus Teleoceras. Cranial features, such as lack of rugose bone for a horn on the dorsal surface of the unfused nasals and pronounced supraorbital tubercles positioned on the frontals dorsal to the orbits, support the establishment of a new species. Additionally, linear measurements and proportions show that T. aepysoma has relatively longer forelimb elements and, thus, a more elevated body than previously described species of Teleoceras. Key words: Teleoceras, new species, Hemphillian, morphology, Gray Fossil Site, Tennessee. TABLE OF CONTENTS Introduction ...........................................................................................................184 Materials and Methods ..........................................................................................186 Results ...................................................................................................................186 Systematic Paleontology .......................................................................................188 Morphological Description ...................................................................................198 Cranium ...........................................................................................................198 Dentition ..........................................................................................................202 Vertebrae and Other Axial Elements ................................................................209 Forelimb ...........................................................................................................215 Hind Limb ........................................................................................................236 Phalanges and Sesamoids ................................................................................249 Discussion .............................................................................................................252 Acknowledgements ...............................................................................................255 Literature Cited .....................................................................................................255 Appendix 1. Measurements Used for Scatterplots ................................................259 184 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) INTRODUCTION Teleoceras is a wide-spread Miocene rhinoceros that has been reported in North American faunas from the late Hemingfordian to the latest Hemphillian North American Land Mammal Ages (NALMA) (Prothero, 1998, 2005; Tedford et al., 2004). In 2000, late Miocene fossils were found during road construction near Gray, Tennessee (Fig. 1A–B; Wallace and Wang, 2004), and the Gray Fossil Site (GFS) was established at the location. In 2004, two nearly complete, articulated rhinoceros skel- etons (Figs. 1C, 2) were discovered and provision- ally referred to Teleoceras cf. T. hicksi (Wallace, 2006). To date, the GFS has produced a minimum of six individuals of Teleoceras based on the pres- ence of four adult left astragali, a subadult femur, and a juvenile, possibly fetal, tibia and fibula pair (Wallace, 2006); however, this number is likely to increase as excavations continue. At the GFS, fossil material is found primar- ily in an organic-rich clay deposit that filled a large sinkhole system in the Knox Group Limestone (Wallace and Wang, 2004). The locality was not a single sinkhole but instead a series of collapsed sinkholes that formed a large basin and, subse- quently, a pond, which likely served as a watering hole for local fauna (Whitelaw et al., 2008; Zobaa et al., 2011). The pond filled with finely laminated lacustrine sediments and isolated gravel lenses over 4,500–11,000 years to an estimated depth of 30–40 m (Shunk et al., 2006, 2009). These fine lamina- tions have contributed to the preservation of many completely or partially articulated fossils. To date, the GFS is one of three Hemphillian fossil localities east of the Mississippi River and outside of Florida along with the Pipe Creek Sink- hole of Indiana and the Mauvilla local fauna of Alabama (Farlow et al., 2001; Prothero, 2005; Hul- bert and Whitmore, 2006). Taxa from the GFS are a mix of North American and Eurasian lineages, and there are genera from warm habitats, includ- ing Alligator, Tapirus, and Heloderma, as well as Figure 1. Geography of the Gray Fossil Site. A, Tennessee; B, Gray, Tennessee indicated with the white star; C, positions of ETMNH 601 and ETMNH 609 at time of excavation with 1 m2 grid. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 185 genera related to modern taxa from cool habitats, such as Arctomeles, Pristinailurus, and Gulo (Wal- lace and Wang, 2004; Mead et al., 2012; Samuels et al., 2018). The GFS has been biochronologically constrained to 4.5–4.9 Ma based on fauna includ- ing Teleoceras, Plionarctos, Gulo sudorus, Tapirus polkensis, and three species of tayassuids (Wallace and Wang, 2004; Hulbert et al., 2009; Doughty et al., 2018; Samuels et al., 2018). During the late Miocene, the North American climate was warmer and drier than today. Expan- sion of grasslands was producing more open habi- tats across much of the continent’s center (Ström- berg and McInerney, 2011). Yet, in a palynological assessment, Ochoa et al. (2012, 2016) found that 90% of the flora at the GFS was Quercus, Carya, and Pinus. Despite being deposited during a time of climatic and environmental change, it is believed that the landscape surrounding the GFS remained a forest, possibly as a refugium, throughout its depositional history, and that resident Teleoceras adopted a browsing ecology (Wallace and Wang, 2004; DeSantis and Wallace, 2008). Appearance of Teleoceras in the North Amer- ican fossil record has been used, along with other taxa, to indicate the beginning of the late Heming- fordian NALMA (He2, ~17.5 Ma), and its disap- pearance, with other taxa, indicates the termination of the Hemphillian NALMA (Hh4, ~4.8 Ma; Ted- ford et al., 2004). Most recently, Prothero (2005) recognized nine species of Teleoceras: T. ameri- canum (Yatkola and Tanner, 1979), T. medicornu- tum Osborn, 1904, T. meridianum (Leidy, 1865), T. brachyrhinum Prothero, 2005, T. major Hatcher, Figure 2. Mounted cast of ETMNH 609 on public display at the East Tennessee State University Museum of Natural History, Gray, Tennessee. 186 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) 1894, T. proterum (Leidy, 1885), T. fossiger (Cope, 1878), T. hicksi Cook, 1927, and T. guymonense Prothero, 2005. Previous work on Teleoceras has focused on skulls and dentition, which has caused much con- fusion and uncertainty (Prothero, 2005); relatively little work has been done on postcranial elements (Mead, 2000; Prothero, 2005). With two nearly complete skeletons available, we present the results of a morphometric comparison of Teleoceras from the GFS and the other nine species, recognize the GFS specimens as a new species, and offer a detailed, thorough bone-by-bone description of the Teleoceras from the GFS. MATERIALS AND METHODS Morphological descriptions of the GFS population were written with the aid of Barone (1999), Flower (1876), McFadyean (1908), Osborn (1898a), and Prothero (2005). Dental morphology is modified from Garutt (1994) and Prothero (2005), and lin- ear measurements come from Prothero (2005). Five cranial measurements (i.e., distance from P2 to occiput, distance from lambdoid crest to nasals, width at zygoma, width of occiput, and height of occiput) and six dental measurements (i.e., lengths of P2–M3, P2–4, M1–3, p3–m3, p3–4, and m1–3) captured skull morphology (Fig. 3). Four postcra- nial linear measurements (i.e., length, proximal width, distal width, and midshaft width) were taken on humeri, radii, ulnae, femora, tibiae, third meta- carpals, and third metatarsals (Fig. 4). Three linear measurements (i.e., length, midshaft width, and width of the sustentaculum) were taken on calca- nea (Fig. 4). Measurements were obtained with an osteometric board and recorded to the nearest 0.1 of a millimeter or calipers and recorded to the near- est 0.01 of a millimeter. Mean values from the GFS were plotted with existing data (Prothero, 2005; Appendix 1) in scatter plot matrices using R Soft- ware (R Core Team, 2016). AbbreviAtions ETMNH, East Tennessee State University Museum of Natural History; GFS, Gray Fossil Site, Gray, Tennessee; NALMA, North American Land Mammal Age. RESULTS Skulls from the GFS are larger than those of other species of Teleoceras with a greater length from P2 to the occiput and greater widths across the zygoma and occiput (Fig. 5; Table 1). Yet, the GFS skulls maintain the characteristically brachycephalic skull of the genus relative to Aphelops and Perac- eras. Dental measurements are consistent across the genus except for upper tooth row lengths of T. fossiger and T. proterum, which are considerably longer than those of other species (Fig. 5). Postcranial measurements of the GFS speci- mens are provided in Table 2. Humeri from the GFS have a greater length, midshaft width, and distal width than other species (Fig. 6). The GFS humeri consistently plot outside of the cluster cre- ated by other species of Teleoceras. Radii from the GFS have a greater length than other species (Fig. 6). However, radial distal and midshaft widths from the GFS plot within the cluster of the other Teleo- ceras species. Ulnae from the GFS have a greater length and midshaft width than other species and plot considerably beyond the cluster of Teleoceras species (Fig. 7). Interestingly, the proportional differences observed in the forelimb elements are not evident in the hind limb or podial elements. Femora from the GFS have a slightly greater length than femora of other species (Fig. 8), but the midshaft width and distal width plot within the cluster of Teleoc- eras species. Tibiae from the GFS are within the cluster of Teleoceras species for length, midshaft width, and distal width (Fig. 8). Podial elements are also within the cluster of Teleoceras species, which is to be expected from a genus characterized by derived, yet conservative, podial morphology (Prothero, 2005; Fig. 9). Third metapodials from the GFS have a slightly greater proximal width, and calcanea from the GFS have a slightly greater length and are one of the widest at the sustentacu- lum. Teleoceras calcanea form a nearly linear trend with the GFS at the largest end and, interestingly, this corresponds closely to taxonomy through time. Skulls and limb elements of the GFS Teleoc- eras are proportionally different from the currently recognized nine species. In addition to unique SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 187 Figure 3. Skull and dental linear measurements. 1, height of occiput; 2, lambdoid crest to nasals; 3, width at zygoma; 4, width of occiput; 5, P2 to occiput; 6, P2−M3; 7, P2−P4; 8, M1−M3. Lower dentition was measured similarly: p2−m3, p2−p4, and m1−m3. Measurements are from Prothero (2005). 188 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 4. Postcranial linear measurements. A, humerus; B, ulna; C, femur; D, radius; E, third metacarpal; F, tibia; G, calcaneum. For A−F: 1, maximum length; 2, maximum proximal width; 3, maximum distal width; 4, midshaft width. For G: 1, maximum length; 2, midshaft width; 3, width of the sustentaculum. Measurements are modified from Prothero (2005). morphological characters, these features warrant emended diagnoses of Teleoceratini and Teleoc- eras as well as the designation of a new species (Table 3). SYSTEMATIC PALEONTOLOGY Class MAMMALIA Linnaeus, 1758 Order PERISSODACTYLA Owen, 1848 Family RHINOCEROTIDAE Owen, 1845 Tribe TELEOCERATINI Hay, 1902 Emended diagnosis.—Retained characters from Prothero (2005:94): “robust, flattened carpals, tarsals, and metapodials…a very brachycephalic skull with a flaring lambdoid crest and broad zygo- matic arches…nasals that are U-shaped in cross- section, with or without a small terminal horn… a strong, lobal antecrochet on the upper molars, and an elongate calcaneal tuber.” Rejected characters from Prothero (2005) are provided in the remarks below. Remarks.—Presence of most characters of Teleoceratini supports placing the GFS specimens in this tribe rather than the subfamily Aceratheriinae (Table 3). Aceratherines, including Peraceras and Aphelops, were the only other North American rhi- noceroses during the late Neogene. Aceratherines are characterized by reduced premaxillae, reduced medial flanges of lower tusks, narrow skulls, and long legs. The GFS fossils exhibit several distinct features (see diagnosis below) that not only warrant SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 189 Table 1. Teleoceras aepysoma cranial measurements (mm). See Figure 3 for measurement schematic. Mean ETMNH 601 ETMNH 609 Skull height of occiput 196.54 201.63 191.45 lambdoid crest to nasals 455.49 493.39 417.59 width at zygoma 357.18 377.15 337.21 width of occiput 235.61 246.29 224.94 P2 to occiput 519.76 530.74 508.78 Dentition P2–M3 265.99 264.45 267.54 P2–P4 116.29 114.06 118.53 M1–M3 158.85 162.42 155.29 p3–m3 246.84 249.44 244.24 p3–p4 82.33 82.21 82.46 m1–m3 165.74 167.60 163.89 erection of the new species, but also call in to ques- tion some of the characters used to define the tribe. The new species described below justifies remov- ing the following characters from the tribe diagno- sis of Prothero (2005:94): “short, stumpy limbs… [and] a nasal incision retracted to anterior P3 (not as far as in aceratheriines).” The latter character is not evident on examined skulls of Teleoceras and is believed to be poorly defined. Genus TELEOCERAS Hatcher, 1894 Emended diagnosis.—Retained characters from Prothero (2005:94): “medium- to large-sized teleoceratin rhinos with hypsodont teeth, strong antecrochets, greatly reduced premolars with dP1/ p1 lost and occasional loss of P2/p2, thick cement on teeth, narrow nasals with strongly downturned lateral edges, enlarged premaxilla and I1, broad zygomatic arches, flaring lambdoid crests (skull semicircular in posterior view)…lower tusk (i2) shaped like a teardrop in cross-section, and…bar- rel-shaped trunk.” Rejected characters from Pro- thero (2005) are provided in the remarks below. Included species.—T. americanum (Yatkola and Tanner, 1979); T. medicornutum Osborn, 1904; T. brachyrhinum Prothero, 2005; T. meridianum (Leidy, 1865); T. fossiger (Cope, 1878); T. proterum (Leidy, 1885); T. hicksi Cook, 1927; T. guymonense Prothero, 2005; T. aepysoma n. sp. Remarks.—Teleoceras is the only North American genus of Teleoceratini, and presence of most characters supports referring the GFS specimens to this genus (Table 3). The GFS fos- sils exhibit several distinct features (see diagnosis below) that not only warrant erection of the new species, but also call in to question some of the characters used to define the genus. Specifically, the new species justifies removing the following characters from the generic diagnosis of Prothero (2005:94): “a small terminal nasal horn and fused nasals…teleoceratin body proportions…and short, robust limbs.” TELEOCERAS AEPYSOMA n. sp. Teleoceras sp. Parmalee et al. (2002); Wallace and Wang (2004); Shunk (2006) Teleoceras cf. T. hicksi Shunk et al. (2006); DeSantis and Wallace (2008); Hulbert et al. (2009) Teleoceras sp. nov Wallace et al. (2014) Diagnosis.—Teleoceras aepysoma has 190 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Table 2. Teleoceras aepysoma postcranial measurements (mm). See Figure 4 for measurement schematic. For the metacarpal, the mean is calculated from the means of individuals to prevent duplicating values for ETMNH 601 and ETMNH 609. Unavailable measurements are indicated with dashes, and unavailable elements are indicated with a gray background. M ea n ET M N H 6 01 R ig ht ET M N H 6 01 Le ft ET M N H 6 09 R ig ht ET M N H 6 09 Le ft ET M N H 8 27 1 R ig ht Humerus Length 392.5 -- -- 392.0 393.0 Proximal Width 157.6 161.0 -- 150.0 158.5 Distal Width 154.1 161.5 161.5 146.8 146.8 Midshaft Width 76.08 77.27 75.58 74.02 77.44 Ulna Length 388.8 403.5 401.0 372.0 378.5 Proximal Width 53.21 57.78 58.45 45.88 50.74 Distal Width 66.72 68.59 67.54 66.97 63.78 Midshaft Width 59.20 60.50 59.80 58.57 57.91 Radius Length 310.6 328.3 321.8 296.5 295.8 Proximal Width 100.4 101.8 103.0 99.0 98.0 Distal Width 97.9 103.0 103.5 93.3 91.8 Midshaft Width 48.84 51.89 52.22 45.36 45.89 MC3 Length 125.6 140.3 139.0 118.0 118.5 119.0 Proximal Width 69.8 77.0 75.0 67.0 66.0 67.0 Distal Width 64.8 73.5 73.0 60.3 59.5 61.3 Midshaft Width 52.11 58.03 58.55 48.65 48.79 49.32 Femur Length 491.6 505.8 513.3 472.3 475.0 Proximal Width 190.4 200.0 196.8 183.3 181.5 Distal Width 134.4 140.5 139.8 129.0 128.5 Midshaft Width 69.99 75.21 73.13 66.15 65.50 Tibia Length 271.5 -- 290.8 253.0 251.5 Proximal Width 112.2 122.0 117.5 103.3 105.8 Distal Width 90.1 94.3 94.8 87.0 84.3 Midshaft Width 51.44 -- 53.35 51.41 47.67 Calcaneum Length 140.2 149.5 151.0 130.0 130.3 Midshaft Width 44.30 48.20 44.56 41.54 42.91 Width at Sustentaculum 77.06 81.67 79.56 75.52 71.50 SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 191 Figure 5. Measurements of Teleoceras skulls and dentition. See Figure 3 for measurement schematic. Teleoceras aepysoma data are compared to data from Prothero (2005; see Appendix 1). Table 2. Continued. MT3 Length 105.2 114.5 113.0 96.3 97.0 Proximal Width 54.3 56.0 57.5 52.0 51.5 Distal Width 59.8 64.3 66.5 53.8 54.5 Midshaft Width 45.53 49.73 50.11 40.89 41.41 192 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 6. Measurements of Teleoceras humeri and radii. See Figure 4 for measurement schematic. Teleoceras aepysoma data are compared to data from Prothero (2005; see Appendix 1). SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 193 large skulls with a greater length from P2 to the occiput and greater widths across the zygoma and the occiput than other species of Teleoceras. As adults, male T. aepysoma have unfused nasals, lack evidence of a nasal horn, and have extensive dorsal tubercles superior to the orbits (supraorbital tubercles). Forelimb bones (i.e., humerus, radius, and ulna) of T. aepysoma are longer than in other species of Teleoceras. Humeri and ulnae also have greater midshaft widths and distal widths. In the hind limbs, femora are slightly longer than other species of Teleoceras. As a result of the longer limb bones, the body of T. aepysoma is more elevated, especially at the front end, than is typical of the genus. Characters are provided in Table 3. Etymology.—“Aepy,” Greek for high or tall, and “soma,” Greek for body; referring to the elevated stance of this species relative to congenerics. Types.—Holotype, ETMNH 609, complete Figure 7. Measurements of Teleoceras ulnae. See Figure 4 for measurement schematic. Teleoceras aepysoma data are compared to data from Prothero (2005; see Appendix 1). skeleton, missing only one distal phalanx. Paratype, ETMNH 601, nearly complete skeleton. Type locality is the Gray Fossil Site, Gray, Washington County, Tennessee, USA (Fig. 1). A cast of the holotype is on public display at the ETMNH (Fig. 2). A paratype is assigned because of its better- preserved skull (Fig. 10). Zoobank Nomenclatural Act.—D3CCE3BC- 98AA-4D98-8727-86999FC6D248. Occurrence.—Latest Hemphillian, late Mio- cene to early Pliocene. Teleoceras aepysoma is cur- rently only known from the Gray Fossil Site, Gray, Washington County, Tennessee. Referred specimens.—Partial skeleton: ETMNH 19280; Cranial: ETMNH 12175, 17351, 17352, 17353, 21659; Dentition: ETMNH 566, 780, 781, 3763, 5235, 7894, 12487, 13914; Ver- tebra: ETMNH 559, 573, 3751, 12175, 13510, 17354; Rib: ETMNH 3747, 3752, 3754, 4286, 6037, 6649, 6749, 7291, 7294, 8173, 8182, 8636, 10959, 12242, 14174, 14710, 14894, 17355, 17356; Humerus: ETMNH 5057, 6648; Ulna: ETMNH 502, 8762; Partial manus: ETMNH 8271; Trapezium: ETMNH 13236; Magnum: ETMNH 8516; Femur: ETMNH 3721; Tibia with fibula: ETMNH 19025; Astragalus: ETMNH 1901, 6647, 14175; Mesocuneiform: ETMNH 3749; Metapo- dial: ETMNH 565; Podial: ETMNH 62; Phalanx: ETMNH 80, 107, 564, 712, 713, 743, 769, 3755, 4381, 5233, 11651, 12175, 12450, 12776, 12777, 13031, 13968, 17357. Remarks.—All specimens from the GFS are well-preserved with minimal breakage or other dis- tortion. Two nearly complete skeletons have been recovered along with isolated elements from other individuals. ETMNH 609 is smaller and is only missing the distal phalanx of the left hind fourth digit. ETMNH 601 is a larger individual, but is less complete than ETMNH 609. ETMNH 601 has the skull, dentition, and most of the appendicular skeleton, though it is more damaged than that of ETMNH 609; however, ETMNH 601 is missing most of the axial skeleton. ETMNH 19280 is a partial skeleton that includes a fragmented dentary with fragmented teeth, partial vertebrae and ribs, right distal tibia and fibula, left third metatarsal, 194 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 8. Measurements of Teleoceras femora and tibiae. See Figure 4 for measurement schematic. Teleoceras aepysoma data are compared to data from Prothero (2005; see Appendix 1). SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 195 and associated unidentified fragments. Both ETMNH 609 and ETMNH 601 are con- sidered males because of their large, tusk-like i2s. This is in contrast to the smaller i2s found in female rhinoceroses (Osborn, 1898a, 1898b; Voorhies and Stover, 1978; Dinerstein, 1991). Both skeletons are also adults based on the degree of epiphyseal fusion and tooth wear. The upper tooth row of ETMNH 609 matches age class XI of Hitchins (1978) and the lower tooth row matches age class X. The larger ETMNH 601 matches age class XIII of Hitchins (1978) on the upper teeth and age class XII on the lower teeth. Using Mihlbachler’s (2003) life span percentages, ETMNH 609 was at the beginning of an age class marking 25–35% of its potential life span and ETMNH 601 was at the beginning of an age class marking 35–52% of its potential life span. In extant Diceros, these life span percentages refer to 8–12 years old and 11–18 years old, respectively (Hitchins, 1978). Mass estimates suggest Teleoceras aepy- soma is quite large. Using equations based on the circumferences of the humerus and femur (Ander- son et al., 1985), the mass of ETMNH 609 is esti- mated to be 1488 kg and 1335 kg, respectively, and that of ETMNH 601 is estimated to be 2330 kg and 2147 kg. These same equations produced mass estimates of 702 kg and 568 kg for T. pro- terum from the Love Bone Bed (MacFadden and Hulbert, 1990). The substantially greater mass estimates for T. aepysoma are corroborated by cal- culations using the calcaneum and constants from two modern rhino taxa (Ceratotherium simum and Diceros bicornis) (Christiansen, 2002). Mass was estimated separately for each constant and then averaged. Using this method, the estimated masses of ETMNH 609 and ETMNH 601 are 1544 kg and 2268 kg, respectively. Figure 9. Measurements of Teleoceras podial elements. See Figure 4 for measurement schematic. Teleoceras aepysoma data are compared to data from Prothero (2005; see Appendix 1). 196 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Table 3. Morphological characters of Teleoceratini, Teleoceras, and T. aepysoma n. sp. Teleoceratini synapomorphies and Teleoceras characters are quoted from Prothero (2005:94). Those that are present in Teleoceras aepysoma are indicated with ‘*,’ those absent are indicated with ‘X,’ and one that is questionably defined is indicated by ‘?.’ Synapomorphies of Teleoceratini T. aepysoma 1. short, stumpy limbs X 2. robust, flattened carpals, tarsals, and metapodials * 3. very brachycephalic skull * 4. flaring lambdoid crest * 5. broad zygomatic arches * 6. nasals that are U-shaped in cross-section * 7. nasals with or without a small terminal horn * 8. nasal incision retracted to anterior P3 (not as far as in aceratheriines) ? 9. strong, lobal antecrochet on the upper molars * 10. elongate calcaneal tuber * Characters of Teleoceras T. aepysoma 1. hypsodont teeth * 2. strong antecrochets * 3. greatly reduced upper and lower premolars * 4. deciduous p1s lost and occasional loss of p2s * 5. thick cement on teeth * 6. narrow nasals with strongly downturned lateral edges * 7. enlarged premaxilla and I1 * 8. broad zygomatic arches * 9. flaring lambdoid crests (skull semicircular in posterior view) * 10. small terminal nasal horn X 11. fused nasals X 12. i2 (tusk) shaped like a teardrop in cross-section * 13. teleoceratine body proportions of a barrel-shaped trunk and short, robust limbs X New Characters of Teleoceras aepysoma 1. greater length from P2 to the occiput than other species 2. greater widths across the zygoma and the occiput than other species 3. unfused nasals 4. no evidence of a nasal horn 5. extensive dorsal tubercles superior to the orbits 6. humerus, radius, ulna, and femur with greater lengths than other species 7. humerus and ulna with greater midshaft and distal widths than other species 8. more elevated body than considered typical of the genus SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 197 Figure 10. Cranium of ETMNH 601 in three views. The upper tusks are removed in this image. A, right lateral view; B, dorsal view; C, ventral view. Anterior is to the right in all three. Scale bar = 10 cm. 198 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) MORPHOLOGICAL DESCRIPTION CrAnium Nasal.—Anteriorly, the nasals are round in cross-section and, when visible, articulate along a coarsely serrated suture (Fig. 11). No evidence of a horn attachment is present on the smooth dorsal surface. Ventrally, the surface is concave and has an anteroposterior ethmoid crest. Nasals become progressively thicker in cross-section toward the anterior suture. ETMNH 609 has only slightly more anteriorly upturned nasals than the straight nasals of ETMNH 601. Frontal.—Dorsally, the frontals are flat except for laterally extending supraorbital tubercles positioned dorsal to the orbits that are unique to this taxon (Fig. 12). Parietal.—Laterally, the parietals are inflated around the braincase (Fig. 13). A broad concavity is present at the articulation between the squamosal and the parietal and dorsal to the external auditory meatus. Paired temporal crests extend posteromedially from the supraorbital tuberosities of the frontals until they nearly merge dorsally, before separating at the lambdoid crest; the temporal crests of ETMNH 601 merge to form a sagittal table. Premaxilla.—Premaxillae of ETMNH 601 are complete and are nearly articulated at their anterior-most point (Fig. 14). Anteroventrally- oriented tusk alveoli are present and support the I1s. Premaxillae of ETMNH 601 are medially flattened, laterally flared, dorsally rounded, and posteroventrally pinched. No nasal or palatine processes are present and there is no evidence of an incisive foramen. Both premaxillae of ETMNH 609 have been entirely reconstructed so that the upper tusks occlude with the lower tusks. Maxilla.—Except for the incisors, the maxilla supports the entirety of the upper tooth row (Fig. 15). Though the facial surfaces are present, most of the internal maxilla of ETMNH 601 is missing. Between the premaxillae articulations, the maxillae are concave to form a rounded incisive cleft at the anterior end of the palate. On the lateral surface, there is a concavity anterior to the lacrimal and ventral to the nasal. Posterolaterally, the maxilla expands laterally to articulate with the jugal and form the anterior zygomatic arch. The maxillary tuberosity continues posteromedially to the jugal articulation at the end of the tooth row. A superior maxillary sinus is within the maxillary tuberosity. A facial crest is bordered by a groove between the maxillary tuberosity and the jugal articulation. Both ETMNH 601 and ETMNH 609 have anteriorly deep maxillary palates that rise to the level of the tooth alveoli at the posterior end. Lacrimal.—This small bone forms the anterior edge of the orbit (Fig. 16). Though the facial surface is rugose, the orbital surface is smooth. There is a laterally-directed lacrimal foramen just beneath a laterally-protruding lacrimal tubercle. Jugal.—The jugal articulates with the maxilla superior to the M1 and M2 (Fig. 17). With the squamosal, the jugal forms the broad and rugose zygomatic arch. Minimal roughness is present on the facial surface, but along the ventral edge of the orbit, the jugal is smooth. There are heavy rugosities on the medial side of the zygomatic arch. Squamosal.—Like the jugal, the medial surface of the squamosal has prominent muscle scarring (Fig. 18). The posterolateral squamosal is more rugose along the medial curve from the zygomatic arch to the parietal articulation and, in doing so, forms the lateral boundary of the temporal fossa. A transversely elongate glenoid fossa has an open angle and is only slightly concave. Anterior to the glenoid fossa, the articular tubercle is round, but it appears pinched anteriorly. Post-glenoid processes are nearly straight and elongate but are shorter than the paroccipital processes of the occipital. These two processes fuse ventral to the external auditory meatus to form the mastoid crest but are then separated by a ‘V’-shaped notch. Dorsal to the external auditory meatus, the squamosal and occipital bones fuse to form the lambdoid crest. There is no evidence of external auditory bullae. Occipital.—On the posteroventral surface, the triangular (in posterior view), convex occipital condyles are lateral to the foramen magnum (Fig. 19). On the ventral surface, the paired hypoglossal foramina are anterior to each of the occipital SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 199 condyles and medial to each paroccipital process. Most of the occipital extends in the same plane as the occipital condyles and only the dorsal-most lambdoid crest extends more posteriorly. Edges of the occipital form the lambdoid crest with the squamosal and parietals. At the ventral point of the external auditory meatus, the lambdoid crest meets the crest of the post-glenoid process and then continues as the paroccipital process. ETMNH 609 has an asymmetrical lambdoid crest that may be due to pathology but further examination is needed. Basicranium.—Because of the large amount of fusion, it is difficult to discern the individual bones of the basicranium, so it will be described Figure 11. Nasals of ETMNH 601. A, dorsal view; B, anterior view; C, right lateral view. In A and B, the scale bar = 5 cm. In C, the scale bar = 10 cm. 200 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 12. Frontals of ETMNH 601. A, right lateral view; B, dorsal view. Abbreviations: DOK, dorsal orbit knobs; OR, orbit; TF, temporal fossa. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 201 Figure 13. Parietals of ETMNH 601. A, right lateral view; B, dorsal view. Abbreviations: CV, concavity; EAM, external auditory meatus; LCT, lambdoid crest; TCT, temporal crest. Scale bar = 10 cm. 202 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 14. Premaxillae of ETMNH 601. Views: A, right lateral; B, anterior. Abbreviations: TAL, tusk alveolus. Scale bar = 10 cm. here as a region (Fig. 20). Ventrally, the basicranium is in poor condition on both crania. There is a ventral muscle tubercle anterior to what is most likely the articulation between the occipital and the basisphenoid. Each lateral side of this region has an alisphenoid canal that is bridged by bone, likely the alisphenoid, with prominent surficial ridges. A dorsal opening to this canal is anterior and the canal gently curves posteroventrally. Pterygoid.—Pterygoid processes are directed posteroventrally and almost to the height of the M3 (Fig. 21). Palatine.—Almost all of the palatine of ETMNH 601 has been repaired with mesh making it nearly impossible to describe any morphology (Fig. 22). Vomer.—The unpaired vomer is missing from both skulls. Hyoid Apparatus.—The basihyoid is round but is dorsoventrally compressed and lacks a lingual process (Fig. 23). The left thyrohyoid of ETMNH 601 is present and it extends posterolaterally from the basihyoid. A rugose knob forms the articulation and the thyrohyoid tapers so that it is mediolaterally compressed. The ceratohyoid is short with rounded sides, and it would articulate between the basihyoid and the epihyoid; though, no epihyoids are present. Finally, the stylohyoid articulates with the epihyoid and the tympanohyoid cartilage. The stylohyoid is the largest of the hyoid bones and is mediolaterally compressed with a medial fossa at the proximal end. There are no tympanohyoids present. North American rhinoceros hyoids were previously only known from Teleoceras major at Ashfall Fossil Beds State Historical Park (Prothero, 2005). Mandible.—Overall, the mandible is much longer than it is tall and the intermaxillary space is ‘V’-shaped (Fig. 24). A shallow, sloping symphysis with a broad lingual surface is present between the dentaries and extends posteriorly to the middle of the p4. Angles of the dentaries are flared laterally and are rugose, especially on ETMNH 601, which is likely due to increased muscle attachment associated with a more advanced age. Each lateral surface has a broad and shallow masseteric fossa that is dorsal to the angular rugosities, which are present on both the medial and lateral side of the dentary. Though there are no angular processes, shallow mandibular incisures separate thin, rounded coronoid processes from transversely long and convex articular condyles. Posterior to each articular condyle, there is a second convex surface that merges with the lateral articular condyle and slopes medioventrally. Below the medial edge of the tusks, there are variable foramina. A short diastema is transversely pinched behind the tusks and separates the tusks from the p2, if present, or the p3. A mental foramen is found inferior to the anterior root of the p4. An inferior mandibular foramen is on the internal pterygoid fossa of the ramus at the same level as the tooth row. Dentition Along each upper tooth row, there is a modified incisor and six lophodont cheek teeth. Along each lower tooth row, there is a modified incisor and five functional, lophodont cheek teeth. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 203 Figure 15. Maxillae of ETMNH 601. Views: A, right lateral; B, ventral. Abbreviations: CV, concavity; FCT, facial crest; IOF, infraorbital foramen; MPL, maxillary palate; MTB, maxillary tuberosity; NI, nasal incision; TR, tooth row. Scale bar = 10 cm. Some lower dentitions include vestigial p2s that are not functional. Dental nomenclature is provided in Figure 25. Upper Incisors.—Upper tusks are modified I1s that are smaller than the lower tusks (Fig. 26). These upper tusks are ovate, elongate mediodorsally to lateroventrally, and function to hone the lower tusks during occlusion. Similar upper tusks are present in other species of Teleoceras, while these are lacking in Aphelops and Peraceras, the other common late Neogene rhinoceroses of North America (Prothero, 2005). 204 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 16. Right lacrimal of ETMNH 601 in lateral view. Abbreviations: FS, facial surface; LF, lacrimal foramen; LTB, lacrimal tuberosity; OS, orbital surface. Scale bar = 10 cm. Upper Cheek Teeth.—Occlusal surfaces of the upper cheek teeth make the ‘π’ shape that is characteristic of rhinoceroses (Fig. 27). Upper premolars are rectangular with the longest axis oriented labiolingually, and, though the M1 is nearly square, the M2 is longer anteroposteriorly. M3s are smaller and form a triangular shape because the crochet is folded within the antecrochet. The P2s have very small crochets, and P3–M3 have large crochets and antecrochets. In all of the premolars, the ectoloph is either shorter than or equal in length to the protoloph and metaloph. Three lophs of the M1s are subequal in length whereas the ectolophs of the M2s are longer than both the protolophs and the metalophs of the same tooth. On the M3s, there are no metalophs, and the ectolophs are approximately the same length or longer than the protolophs. On P3–M3, the anterior parastyle overlays the posterior metastyle of the previous tooth. All upper cheek teeth have slight depressions lined by cingula on the anterior and lingual sides of the protocone, and all molars have a slight paracone fold on their labial surfaces. On some teeth, small folds of enamel protrude into the fossettes (e.g., P4 of ETMNH 609, Fig. 27B). Lower Incisors.—Lower tusks are i2s that have a tear-drop shaped cross-section with the point directed medially (Fig. 28). Complete tusks of ETMNH 609 and ETMNH 601 have concave wear surfaces caused by occlusion with the upper tusks resulting in a sharp edge and apex. Lower Cheek Teeth.—Most often, p1 and p2 are absent from Teleoceras dentition. There are no p1s present in T. aepysoma; however, presence of the p2 is variable. ETMNH 601 does not have p1 or p2 on either side; however, ETMNH 609 has a small vestigial p2 (Fig. 29) that was first noted by Wallace (2006), and ETMNH 21659 has both the SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 205 Figure 17. Jugals of ETMNH 601. Views: A, right lateral; B, ventral. Abbreviations: OF, orbital floor; OR, orbit; ZMA, zygomatic arch. Scale bar = 10 cm. 206 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 18. Squamosals of ETMNH 601. Views: A, right lateral; B, ventral; Abbreviations: ATB, anterior tubercle; GF, glenoid fossa; PGP, post-glenoid process; POC, paroccipital process; TF, temporal fossa. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 207 Figure 19. Occipital of ETMNH 601. Views: A, ventral; B, posterior. Abbreviations: EAM, external auditory meatus; FM, foramen magnum; HGF, hypoglossal foramen; LCT, lambdoid crest; MCT, mastoid crest; OCD, occipital condyles; POC, paroccipital process. Scale bar = 10 cm. 208 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 20. Basicranium of ETMNH 601. Views: A, ventral; B, right ventrolateral, beneath zygomatic arch, with arrows pointing at both ends of the alisphenoid canal. Abbreviations: ASC, alisphenoid canal; MTB, muscle tubercle. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 209 right and left p2s. Lower premolars have the ‘W’ shape that is characteristic of rhinoceroses and lack significant cingula (Fig. 30). vertebrAe AnD other AxiAl elements Atlas.—A round dorsal tubercle is present along the midline of the dorsal arch, which narrows caudally (Fig. 31). A minimal ventral tubercle mir- rors the odontoid process of the axis. The ventral arch is more robust than the dorsal arch. Dorsally, the neural canal is round and, ventrally, it is ‘U’- shaped. At the base of the dorsal arch, lateral ver- tebral foramina are located slightly more cranially. Transverse foramina are present on the medioven- tral surface of the transverse processes. At the lat- eral-most ends of the transverse processes, there is a great amount of rugose bone present on ETMNH 601 that is not present on ETMNH 609; likely this is because ETMNH 601 is the older and larger of the two individuals. On the cranial surface, articular surfaces for the occipital condyles are craniomedi- ally depressed to form a pair of concave tear-drop shaped facets that narrow ventromedially. Caudal articular surfaces are ovate with the elongate axis extended mediolaterally from the ventral neural canal to the transverse vertebral foramina. Axis.—Axes are taller and wider than they are long and have large rounded odontoid pro- cesses for articulation with the atlas (Fig. 32). Caudally, the centrum is concave as typically seen in the opisthocoelous vertebrae of perissodactyls. Dorsally, the neural canal is domed, but, ventrally, it is flattened. Transverse foramina are present; though they are completely closed on ETMNH 601 and only partially closed on ETMNH 609. Figure 21. Pterygoids of ETMNH 601 in ventral view. Abbreviation: PGP, pterygoid process. Scale bar = 10 cm. 210 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Only minimal transverse processes are present. Prezygapophyses are expanded mediolaterally from the odontoid process. Postzygapophysis pro- cesses extend laterally and caudally to form ovate facets. Deep cranial notches are present dorsal to the prezygapophyses and caudal vertebral notches are rounded between the ventral postzygapophyses and the dorsal centrum. Third–Seventh Cervical Vertebrae.—Dor- sally, the neural canal is domed and, ventrally, it is flattened along the dorsal side of the centrum (Fig. 33). On the ventral surface of the centra, there is no evidence of any hemal structures. Round prezyg- apophyses are present on the dorsal surface of the anterior prominences of the vertebrae. These articulate with the round postzygapophyses that are present on the ventral surface of the posterior prominences. Through the cervical series, the neu- ral spines transition from short to pronounced, and the transverse processes vary from a simple, later- ally-flared extension on the third cervical vertebra to a larger, lateral process with dorsal and ventral Figure 22. Palatines of ETMNH 601 in ventral view. Scale bar = 10 cm. Figure 23. Hyoid apparatus of ETMNH 601 with ceratohyoid from ETMNH 609. Image in dorsal view with anterior to the right. Abbreviations: BAS, basihyoid; CER, ceratohyoid; STY, stylohyoid; THY, thyrohyoid. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 211 Figure 24. Mandible of ETMNH 601. Views: A, right lateral; B, dorsal. Abbreviations: ACD, articular condyle; AD, angle of dentary; CNP, coronoid process; DIA, diastema; IMS, intermaxillary space; MDB, mandibular body; MDI, mandibular incisure; MSF, masseteric fossa; MTF, mental foramen; PGF, pterygoid fossa; SYM, symphysis. Scale bar = 10 cm. 212 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 25. Dental morphology and nomenclature. A, Left M2 of ETMNH 601; B, Right m2 of ETMNH 601. Abbreviations: ACT, antecrochet; ALD, anterior lophid; ALV, anterior lingual valley; CT, crochet; ECD, entoconid; EL, ectoloph; FOS, fossette; HC, hypocone; HCD, hypoconid; ML, metaloph; MS, metastyle; MTC, metacone; MTCD, metaconid; PCC, protocone constriction; PCF, paracone fold; PLD, posterior lophid; PL, protoloph; PLV, posterior lingual valley; PRC, paracone; PRCD, paraconid; PS, parastyle; PTC, protocone; PTCD, protoconid; PTF, post-fossette. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 213 extensions on the sixth cervical vertebra. Charac- teristic transverse foramina are found just lateral to the centra at the origin of the transverse processes. The seventh cervical vertebrae resemble the third through sixth except there is a longer neural spine, a lack of transverse foramina lateral to the centrum, and the transverse processes are missing the ventral processes. Thoracic Vertebrae.—ETMNH 609 has 18 thoracic vertebrae that articulate with 18 pairs of ribs, all of which were articulated when the specimen was found (Figs. 1C, 34). ETMNH 601 has an incomplete thoracic series with only 10 fragmented and concreted vertebrae present. Neural spine height arcs throughout the thoracic series with the third thoracic as the apex until the height becomes consistent at the thirteenth thoracic. In addition to height, the neural spines become more caudally directed through the series. Thoracic neural canals change from triangular at the anterior end of the series to round at the posterior end. Thoracic centra also change from round at the anterior end to heart-shaped at the posterior end. Between the neural spine and the transverse process, the dorsal vertebral arch is more obtuse in the anterior thoracics and becomes more acute in the posterior thoracics. On the first two thoracic vertebrae, the prezygapophyses resemble those on the cervical vertebrae, but, beginning with the third thoracic, the prezygapophyses are smaller in size and are at the base of the anterior neural spine. Through the craniocaudal progression, the dorsal notch between the prezygapophyses becomes narrower and extends more caudally as the prezygapophyses shift medially. Small postzygapophyses are at the Figure 26. Left I1 tusks with occlusal surface down. A, ETMNH 601; B, ETMNH 609. Scale bar = 5 cm. 214 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) base of the posterior neural spine for articulation with the prezygapophyses of the subsequent verte- bra. First and second thoracic vertebrae have prom- inent transverse processes and articulate with small ribs. Third through eighteenth thoracic vertebrae have small transverse processes and articulate with larger ribs. There are three articular surfaces for ribs—the articular facet for the anterior rib head, the articular facet for the posterior rib head, and the costal fovea. Throughout the thoracic series, the size and shape of these facets varies and, in some cases, the anterior articular facet and the cos- tal fovea merge. The eighteenth thoracic lacks the posterior articular facet. On the posterior surface of each vertebra, caudal notches separate the trans- verse processes from the posterior articular facets. Lumbar Vertebrae.—There are only three lumbar vertebrae on ETMNH 609; however, none are preserved on ETMNH 601 (Fig. 35). This is in contrast to many North American rhinocerotids who typically have five lumbar vertebrae (Prothero, 2005); though, modern rhinos are known to have variable vertebral counts both across and within species (Heller, 1914). Lumbar neural spines are thin, anteroposteriorly wide, and angled posteri- orly. Lumbar neural canals are triangular, and they widen through the series. Lumbar vertebrae have considerably more acoelous centra than the tho- racic vertebrae. The posterior centrum of the last lumbar is oval for articulation with the sacrum. The first lumbar vertebra has tighter anterodorsal pro- cesses for articulation with the last thoracic; these are more wide-set on the last lumbar. Prezygapoph- yses are small ovals on either side of the medial notch. Oval postzygapophyses are on the ventral side of the neural spine and on either side of the Figure 27. Right upper cheek teeth (P2–M3) in occlusal view with anterior to the right. A, ETMNH 601; B, ETMNH 609. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 215 dorsal notch. Transverse processes are smallest on the first lumbar vertebrae and largest on the second. On the third lumbar vertebra, the transverse pro- cesses have flat, rugose articular surfaces on their caudal surfaces for articulation with the wings of the sacrum. Sacrum.—Four sacral vertebrae fused to form the triangular sacrum that is wide cranially and narrows caudally (Fig. 36). ETMNH 609 has a complete sacrum but very little of the sacrum of ETMNH 601 is preserved. Sacral foramina are pres- ent on either side of the neural spines and between each adjacent pair of sacral vertebrae. The neural canal appears to be triangular, but this may be an effect of preservation because part of the dorsal surface has collapsed into the caudal portion of the canal. Ovate centra are transversely elongated and dorsoventrally shortened. The first sacral vertebra Figure 28. Left i2 tusks in occlusal view. A, ETMNH 609; B, ETMNH 601. Scale bar = 10 cm. has bulbous prezygapophyses for articulation with the third lumbar vertebra. Rugose cranial margins of the sacral wings are flattened and turned dor- sally so that their dorsal surfaces articulate with the ventral ilia. Caudal notches are smaller than cranial notches and form minimal postzygapophyses that articulate with the first caudal vertebra. Caudal Vertebrae.—ETMNH 609 has 21 caudal vertebrae and ETMNH 601 has 23 (Fig. 37). Through the caudal series, the vertebrae change from a typical vertebral morphology to a more general, non-descript morphology. The first four caudals have distinct neural spines, which become progressively minimized through the cau- dal series. Transverse processes are present on the cranial-most caudals and become smaller until they are simple protuberances just over midway through the caudal series before being lost completely. A dorsoventrally compressed, triangular neural canal curves laterally over the centrum on the anterior caudals, and approximately midway through the series, the neural canal is more round and opened by the posterior progression of the dorsal neural canal notch. The first three caudal vertebrae have small round remnants of pre- and postzygapophy- ses; however, after the third caudal, the only articu- lation between caudals occurs at the centra. Sternebrae.—Sternebrae of ETMNH 609 include the long manubrium with a triangular pro- tuberance, one short sternebra that is compressed on the craniocaudal axis and expanded at both ends, and one round sternebra (Fig. 38). Ribs.—ETMNH 609 has 18 pairs of ribs and ETMNH 601 only has incomplete fragments that do not produce an accurate count. Overall, the ribs are rather unremarkable in their morphology; although, ETMNH 601 has two ribs with patholo- gies (Fig. 39). In addition, each complete skeleton has pieces of ossified costal cartilage that are char- acteristically very porous. Forelimb Scapula.—Robust scapulae are nearly trian- gular in shape with a slightly convex cranial bor- der that is rugose, especially at the proximal angle where it meets the heavily rugose vertebral bor- der (Fig. 40). A concave vertebral border extends 216 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 29. Vestigial left p2 of ETMNH 609. Tooth of interest is indicated by the rectangle. Scale bar = 10 cm. Figure 30. Left lower cheek teeth (p3–m3) in occlusal view with anterior to the right. A, ETMNH 601; B, ETMNH 609. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 217 to form a prominent, rugose angle with the rather straight caudal border. A wide scapular neck sepa- rates the broad scapular blade from the distal site of articulation. An ovate and gently concave glenoid fossa forms the distal end of the scapula and artic- ulates with the humeral head. The glenoid fossa has well-defined edges, except the craniolateral edge, which is modified into a rounded surface as if folded toward the coracoid process to create an extra point of articulation with the proximal head of the humerus. The scapular spine extends nearly the length of the element from just distal of the vertebral point to just proximal of the glenoid fossa. The spine is prominently elevated and curves over the infraspinous fossa toward the caudal angle. Distally, the scapular spine is more elevated, but it slopes to the level of the fossae as it extends proximally. A heavily rugose spinal tuber is triangular but has a rounded apex directed caudally. Medially, the underside of the spine is marked by a depression. Laterally, the smaller supraspinous fossa is depressed near the scapular spine and raised at the cranial border. In the same view, the larger infraspinous fossa is nearly flat, except for a slight raise along the caudal border. Humerus.—The articular head extends posterodistally, so that it curves onto the posterior surface of the humerus (Fig. 41). On the proximal surface, there is a depression posterior to the lesser and intermediate tuberosities and anterior to the humeral head for articulation with the craniolateral portion of the scapula’s glenoid fossa. The greater tuberosity extends proximomedially and with a distinct curvature; the greater tuberosity is broken off of both humeri of ETMNH 601. The convexity of the lesser tuberosity is a slight knob on the medial side of the humeral head. Both the greater and lesser tuberosities are rugose, which indicates strong muscle attachments. A tightly rounded bicipital groove separates the greater tuberosity and the intermediate tubercle. The intermediate tubercle is Figure 31. Atlas of ETMNH 609. Views: A, dorsal; B, anterior; C, left lateral; D, posterior. Abbreviations: CAAS, caudal articular surface; CRAS, cranial articular surface; DA, dorsal arch; DTB, dorsal tubercle; LVF, lateral vertebral foramen; NC, neural canal; TVF, transverse foramen; TVP, transverse process; VA, ventral arch; VTB, ventral tubercle. Scale bar = 10 cm. 218 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) not as prominent as that seen in Equus and, for that reason, was not considered to be present in rhinos by Hermanson and MacFadden (1992). It is being considered as a feature here because it is distinct from the greater and lesser tuberosities and, within rhinos, Teleoceras has a large intermediate tubercle (Mihlbachler, 2013, pers. comm.). In medial view, rugose bone extends from the lesser tuberosity almost to the medial epicondyle. In lateral view, the deltoid tuberosity is distal to the greater tuberosity and, though the deltoid tuberos- ity is small, it is a rugose projection that is directed posteriorly. A pronounced humeral crest originates at the deltoid tuberosity and curves distomedially. Anterodistally, a larger, medial coronoid fossa and a smaller, lateral radial fossa are proximal to the trochlea and capitulum, respectively, and are divided by a very slight ridge. The wide trochlea extends more proximally than the narrow capitu- lum, giving the appearance of a rotated articu- lar surface. Articular surfaces of the trochlea and capitulum curve around the distal end, narrow, and merge before terminating at the distal edge of the olecranon fossa. Epicondyles are robust, and the Figure 32. Axis of ETMNH 609. Views: A, dorsal; B, left lateral; C, anterior; D, posterior. Abbreviations: CAN, caudal notch; CEN, centrum; CRN, cranial notch; NC, neural canal; OP, odontoid process; PRZ, prezygapophyses; POZ, postzygapophyses; TVF, transverse foramen; TVP, transverse process. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 219 medial epicondyle is relatively slender in contrast to the expanded lateral epicondyle. The epicon- dyles form the sides of the olecranon fossa, which is a deep, rounded depression that is proximally open to the diaphysis. From the lateral epicondyle, the epicondylar crest extends proximally to the midpoint of the posterior diaphysis. Ulna.—At the proximal end, the olecranon process is robust with heavy rugosities and numer- ous foramina (Fig. 42). A prominent anconeal pro- cess slants laterally at its proximal point, which is marked with a ‘V’-shaped depression. A broad trochlear notch slants laterally at its proximal end. Two articular processes extend from the distal trochlear notch; the medial of which is wider and longer than the lateral. A deep, rugose radial notch is present between the medial and lateral processes of the trochlear notch. The articular surface of the trochlear notch has a slight concave curvature for articulation with the humerus; the radius acts as a stabilizer for this joint. Ulnar diaphyses are triangular in cross section with the apex along the posterior surface. The ulna has its narrowest point at its proximal Figure 33. Fourth cervical vertebra of ETMNH 609. Views: A, dorsal; B, anterior; C, right lateral; D, posterior. Abbreviations: APR, anterior prominence; CEN, centrum; NC, neural canal; NS, neural spine; POZ, postzygapophyses; PRZ, prezygapophyses; TVF, transverse foramen; TVP, transverse process. Scale bar = 10 cm. 220 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 34. Sixteenth thoracic vertebra of ETMNH 609. Views: A, dorsal; B, right lateral; C, anterior; D, posterior. Abbreviations: AFAR, articular fossa for anterior rib; AFPR, articular fossa for posterior rib; CAN, caudal notch; CEN, centrum; CF, costal fossa; DA, dorsal arch; NC, neural canal; NS, neural spine; POZ, postzygapophyses; PRZ, prezygapophyses; TVP, transverse process. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 221 end just distal to the radial notch and broadens distally. At the distal end, the diaphysis narrows to form the styloid process, which articulates with the cuneiform and the radius. In distal view, the articular surface for the cuneiform is slanted from anterolateral to posteromedial with a central concavity that extends parallel to the slant of the facet. On the proximomedial surface of the styloid process, a small facet extends along the medial edge of the ulna providing a point of articulation with the radius. Radius.—The neck of the radius narrows more on the lateral side to form a diaphyseal curve but is only slightly narrowed on the medial side (Fig. 43). There is a small anteroposterior ridge between the two proximal articular surfaces for the capitulum and trochlea of the humerus. This ridge is offset laterally creating a larger medial articular facet for the trochlea. Also proximally, on the posterior surface, there is a rugose site for attachment to the ulna. A triangular articular surface on the proximolateral side is slightly depressed for articulation with the corresponding facet on the anterior surface of the ulna. On the proximoanterior surface of the radius, there is a radial tuberosity that is rugose but not depressed on the GFS specimens; this feature can form a pronounced fossa on some Teleoceras. Distally, there is a triangular area of rugose bone on the posterolateral surface that fits into the Figure 35. Third lumbar vertebra of ETMNH 609. Views: A, dorsal; B, anterior; C, right lateral; D, posterior. Abbreviations: CEN, centrum; NC, neural canal; NS, neural spine; PRZ, prezygapophyses; POZ, postzygapophyses; TVP, transverse process. Scale bar = 10 cm. 222 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) corresponding area of the ulna. A small, rounded articular facet is along the posterolateral edge for articulation with the ulna. Medially adjacent to that facet is a narrow articular surface for articula- tion with the cuneiform. Two additional articular facets are on the very distal surface and are sepa- rated by a ridge as they slant from anterolateral to posteromedial. A smaller lateral articular surface is depressed on the posterior portion for articulation with the lunar and the more rounded medial articu- lar surface is depressed on the anterior portion for articulation with the scaphoid; together, these form a continuous depression across the slant of the articular surfaces. No remnant of a styloid process is present on the distal radius. Scaphoid.—The scaphoid is the largest of the carpal bones (Figs. 44, 45). Proximally, there is a concave, rounded articular surface for the radius. The medial corner of this surface folds over its raised point to form an articular surface extension. Where the lateral corner is raised, it forms an edge with an anteroproximal articular surface for the lunar. Posterior to the radial facet is the rugose pos- terior process with a second, round articular surface for the lunar on the lateral side. On the posterior side of the lateral extension, there is a third, round articular surface for the lunar. This facet folds over into the triangular laterodistal articular surface for the magnum. A raised ridge is formed by this lat- erodistal and the mediodistal articular surfaces. The mediodistal articular surface for the trapezoid is saddled over the distal surface and extends on both the anterior and posterior surfaces. Lunar.—Overall, the lunar is anteroposte- Figure 36. Sacrum of ETMNH 609. Views: A, dorsal; B, anterior; C, right lateral; D, posterior. Abbreviations: CAN, caudal notch; CEN, centrum; CRN, cranial notch; NC, neural canal; NS, neural spine; PRZ, prezygapophyses; SF1–3, sacral foramina 1–3; SV1–4, sacral vertebrae 1–4; SW, sacral wing. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 223 riorly elongate and mediolaterally narrow (Figs. 44, 46). Most of the articular surfaces are on the anterior two-thirds of the lunar as the posterior one-third forms a rugose process. On the proxi- momedial side of the process, there is an articular surface that is one of the three points of articula- tion with the scaphoid. Proximally, the lunar has a large, convex articular surface for articulation with the radius. Posteriorly, this articular surface slopes distally onto the lunar process, whereas the anterior portion slopes along the anterior surface. Distally, the lunar has two concave articular sur- faces joined at a slightly elevated ridge. The medial facet is a small tear-drop situated more posteriorly for articulation with the magnum. The lateral facet is posteriorly square and anteriorly flared, and it articulates with the unciform. On the medial side, there are two additional articular surfaces for the scaphoid. The proximal of these is elongate antero- Figure 37. Third caudal vertebra of ETMNH 609. Views: A, dorsal; B, right lateral; C, anterior; D, posterior. Abbreviations: CEN, centrum; NC, neural canal; NDN, neural dorsal notch; NS, neural spine; TVP, transverse process. Pre- and post-zygapophyses are not visible in this figure. Scale bar = 10 cm. Figure 38. Sternebrae of ETMNH 609. Scale bar = 10 cm. Figure 39. Ribs of ETMNH 601 showing pathology. Scale bar = 10 cm. 224 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) posteriorly, and the distal one is proximally domed and distally square. On the lateral side, there are also two articular surfaces for articulation with the cuneiform. The proximal of these is oval, and the distal one is thin and oblong. Cuneiform.—Proximodistal and anteropos- terior axes of the cuneiform are long, whereas the mediolateral axis is short (Figs. 44, 47). There is rugose bone extending anteroposteriorly on the distal portion of the lateral side. A proximal articu- lar surface is saddle-like for articulation with the styloid process of the ulna. Laterally, this articular surface curves distally, and medially, it terminates at a ridge with a rectangular articular surface for the lunar. A square articular surface with a rounded anterolateral corner is present on the distal end of the cuneiform for articulation with the unciform. Medially, this ulnar articular surface folds proxi- mally and creates a small, domed articular surface for the lunar. On the posterior side, an oblong artic- ular surface is present for articulation with the pisi- form. This articular surface forms a lateral ridge as it joins the lateral portion of the proximal articular surface. Pisiform.—The pisiform appears to be pinched mediolaterally because it curves medi- Figure 40. Right scapula of ETMNH 609. Views: A, lateral; B, distal. Abbreviations: CCP, coracoid process; CDB, caudal border; CLE, craniolateral edge; CRB, cranial border; GF, glenoid fossa; ISF, infraspinous fossa; SCN, scapular neck; SCS, scapular spine; SSF, supraspinous fossa; ST, spinous tuber; VBB, vertebral border. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 225 Fi gu re 4 1. R ig ht h um er us o f E TM N H 6 09 . V ie w s: A , a nt er io r; B , p os te rio r; C , m ed ia l; D , l at er al ; E , p ro xi m al ; F , d is ta l. A bb re vi at io ns : A H , ar tic ul ar h ea d; B C G , b ic ip ita l g ro ov e; C A P, c ap itu lu m ; C F, c or on oi d fo ss a; H C T, h um er al c re st ; D T, d el to id tu be ro si ty ; E C C , e pi co nd yl ar cr es t; G R 1, g ro ov e on e; G R 2, g ro ov e tw o; G TC , g re at er tu be ro si ty c on ve xi ty ; G TS , g re at er tu be ro si ty su m m it; IM T, in te rm ed ia te tu be rc le ; LE C , l at er al e pi co nd yl e; L TC , l es se r t ub er os ity c on ve xi ty ; L TS , l es se r t ub er os ity su m m it; M EC , m ed ia l e pi co nd yl e; N F, n ut rie nt fo ra m en ; O F, o le cr an on fo ss a; P D , p ro xi m al d ep re ss io n; R F, ra di al fo ss a; T R O , t ro ch le a. S ca le b ar = 1 0 cm . 226 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Fi gu re 4 2. R ig ht u ln a of E TM N H 6 09 . V ie w s: A , a nt er io r; B , p os te rio r; C , m ed ia l; D , l at er al ; E , p ro xi m al ; F , d is ta l. A bb re vi at io ns : A P, an co ne al p ro ce ss ; A R R , a rti cu la r r ug os e bo ne fo r r ad iu s; A SC , a rti cu la r s ur fa ce fo r c un ei fo rm ; A SR 1– 2, a rti cu la r s ur fa ce s fo r r ad iu s 1– 2; LA P, la te ra l a rti cu la r p ro ce ss ; M A P, m ed ia l a rti cu la r p ro ce ss ; O P, o le cr an on p ro ce ss ; R N , r ad ia l n ot ch ; S P, s ty lo id p ro ce ss ; T N , t ro ch le ar no tc h. S ca le b ar = 1 0 cm . SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 227 Fi gu re 4 3. R ig ht r ad iu s of E TM N H 6 09 . V ie w s: A , a nt er io r; B , p os te rio r; C , m ed ia l; D , l at er al ; E , p ro xi m al ; F , d is ta l. A bb re vi at io ns : A SU 1– 3, a rti cu la r s ur fa ce s fo r t he u ln a 1– 3; A SC , a rti cu la r s ur fa ce fo r t he c ap itu lu m ; A SL , a rti cu la r s ur fa ce fo r t he lu na r; A SS , a rti cu la r su rf ac e fo r t he sc ap ho id ; A ST , a rti cu la r s ur fa ce fo r t he tr oc hl ea ; C P, ra di al c or on oi d pr oc es s; N K , r ad ia l n ec k; R C T, ra di al c re st ; R TB , r ad ia l tu be ro si ty . S ca le b ar = 1 0 cm . 228 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) ally and flares posteriorly (Figs. 44, 48). An ante- rior articular surface for the cuneiform is round proximally and square distally. ETMNH 601 has an additional small, round anterolateral articular surface for the ulna that does not occur in ETMNH 609. Trapezium.—The trapezium is a small, rugose bone with a ‘V’-shape pointed distally (Figs. 44, 49). An oval articular surface for the trapezoid is present on the lateral side. ETMNH 601 has a distally extended articular surface for a slight articulation with the second metacarpal. Trapezoid.—A rugose prominence occurs on the anterior surface (Figs. 44, 50). The proximal articular surface for the scaphoid is square with a convexly rounded medial edge and is depressed mediolaterally. At the posteromedial corner of this facet, it forms a ridge with a round, medial articular surface for the trapezium. Distally, the trapezium articular surface folds laterally into the convex, ovate distal articular surface for the second meta- carpal. Laterally, this distal articular surface forms an edge with the lateral kidney-shaped articular surface for the magnum. Magnum.—The magnum is narrower across the mediolateral axis than the anteroposterior axis (Figs. 44, 51). Anteroproximally, there is an articu- lar surface for the scaphoid that is triangular with Figure 44. Articulated carpal bones of ETMNH 609 in anterior view. Abbreviations: CUN, cuneiform; LUN, lunar; MAG, magnum; SCA, scaphoid; TRD, trapezoid; TRM, trapezium; UNC, unciform. The pisiform is not visible in this view. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 229 an anterior straight edge and posterior point that is laterally raised. This raised portion forms a ridge with the triangular posteroproximal articular sur- face, which is saddled over a proximally raised pro- cess, for articulation with the lunar. On the medial surface, there is a kidney-shaped articular surface that articulates with the trapezoid and forms an edge with the anteroproximal facet. Along its distal edge, this articular surface contacts a small, rect- angular articular surface for the second metacar- pal. One articular surface for the third metacarpal covers most of the distal surface of the magnum. Posteriorly, this articular surface extends along a small distal process that mirrors the proximal pro- cess. This facet is slightly curved anteriorly and has a straight medial edge with the second meta- carpal facet. On the lateral side, there is another kidney-shaped articular surface for the unciform. The magna from the GFS lack a posterior process resembling those discussed by Harrison and Man- ning (1983). Unciform.—All of the articular surfaces are on the anterior portion of the unciform and are dis- tolaterally curved (Figs. 44, 52). The posterior por- tion of the unciform consists of a rugose process that can be variable within a population as demon- strated by Harrison and Manning (1983), but it is consistent within the limited sample from the GFS. Two articular surfaces meet at a ridge on the proxi- mal side of the anterior portion. The proximolat- eral articular surface for the cuneiform is slightly convex anteroposteriorly and comes to a rounded point on the lateral side. The proximomedial artic- ular surface is round, longer anteroposteriorly, and Figure 45. Right scaphoid of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASL1–3, articular surfaces for lunar 1–3; ASM, articular surface for magnum; ASR, articular surface for radius; AST, articular surface for trapezoid; PP, posterior process. Scale bar = 5 cm. 230 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) articulates with the lunar. A second medial articular surface is distal to the lunar facet and is ‘C’-shaped for articulation with the magnum. On the distal sur- face, articular facets are present for the third, fourth, and, on ETMNH 601, fifth metacarpals. The more medial third metacarpal and the lateral fourth meta- carpal share the articular surface without a dividing ridge; however, there is an indicative line formed by wear. Overall, the articular surface is triangu- lar with a small convexity along the medial edge near where it contacts the medial articular surface for the magnum. This lateral indentation articulates with the fifth metacarpal or the proximal expansion present on some fourth metacarpals. Second Metacarpal.—Both medial and lat- eral edges are slightly curved medially so the sides appear pinched anteroposteriorly (Fig. 53). There is a slight posterior ridge just medial to the midline of the bone that extends from proximal to distal and, at the posterodistal facets, matches with the inter- mediate relief. On the proximal end, there are three primary articular surfaces. A roughly square medial articular surface for the trapezoid is the largest and has a slight depression in the middle. The lateral edge of this facet is raised to form a ridge with the rectangular proximomedial articular surface for the Figure 46. Right lunar of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASC1–2, articular surfaces for cuneiform 1–2; ASM, articular surface for magnum; ASR, articular surface for radius; ASS1–3, articular surfaces for scaphoid 1–3; ASU, articular surface for unciform; LP, lunar process. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 231 Figure 47. Right cuneiform of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASL1–2, articular surfaces for lunar 1–2; ASP, articular surface for pisiform; ASUL, articular surface for ulna; ASUN, articular surface for unciform. Scale bar = 5 cm. Figure 48. Right pisiform of ETMNH 609. Views: A, anterior; B, dorsal; C, lateral. Abbreviations: ASC, articular surface for cuneiform. Scale bar = 5 cm. 232 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 49. Right trapezium of ETMNH 609. Views: A, proximal; B, distal; C, medial; D, lateral. Abbreviation: AST, articular surface for trapezoid. Scale bar = 1 cm. Figure 50. Right trapezoid of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASM, articular surface for magnum; ASMC2, articular surface for second metacarpal; ASS, articular surface for scaphoid; AST, articular surface for trapezium. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 233 magnum, which slopes distally and laterally from the ridge. At the distal edge, this facet folds into the lateral-most articular surface of the proximal end. This lateral articular surface for the third meta- carpal is rectangular. At the distal end, the ante- rior articular surface for the proximal phalanx is smooth and, though the lateral edge is parallel to the axis of the bone, the medial edge curves later- ally creating a half-dome shape. On the posterior articular surface, two facets are separated by the intermediate relief. Both facets are oval with slight depressions along their midlines, are slanted from proximomedial to distolateral, and each articulates with one sesamoid. Third Metacarpal.—On the anterior surface of the proximal end, there are two rugose knobs that serve as sites of muscle attachment (Fig. 54). Similar rugosities are on the posterior surface as well. In posterior view, a nutrient foramen is pres- ent at the midpoint of the diaphysis along a poste- rior ridge that separates a pair of depressions prox- imal to the distal articular surface. These depres- sions are not as pronounced as those seen in other species of Teleoceras. On the medial and lateral sides of the bone, there are proximal rectangular articular surfaces for the second and fourth meta- Figure 51. Right magnum of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASL, articular surface for lunar; ASMC2–3, articular surfaces for sec- ond and third metacarpals; ASS, articular surface for scaphoid; AST, articular surface for trapezoid; ASU, articular surface for unciform. Scale bar = 5 cm. 234 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) carpals, respectively. A triangular articular surface for the magnum is on the medial side of the proxi- mal end and has a concavity at the narrow posterior end. The lateral proximal articular surface for the unciform is medially domed with a straight lateral edge and a pinched posterior point. Distally, the anterior articular surface for the proximal phalanx of the third digit is smooth and domed proximally. Posteriorly, an intermediate relief divides the distal articular surface into two oval facets for articula- tion with the two sesamoids. Fourth Metacarpal.—Along the diaphysis, the narrower lateral side is more concave than the rugose medial side (Fig. 55). Both the proximal and the distal ends curve further posteriorly than the diaphyseal area giving the appearance that the midsection is depressed. Two articular surfaces are on the proximal end of the fourth metacarpal. Medi- ally, there is a rectangular articular surface for the third metacarpal. The proximal edge of this facet forms a ridge with the medial edge of the proximal articular surface. This proximal articular surface for the unciform is the larger of the two and is indented along the lateral edge. Posteriorly, it folds over a raised portion that forms a tight articulation with the unciform. On ETMNH 601, there is an articular notch lateral to this facet where the fifth metacarpal articulates; however, on ETMNH 609, a remnant Figure 52. Right unciform of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASC, articular surface for cuneiform; ASL, articular surface for lunar; ASM, articular surface for magnum; ASMC3–4, articular surfaces for third and fourth metacarpals; UNP, unciform process. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 235 Figure 53. Right second metacarpal of ETMNH 609. Views: A, anterior; B, posterior; C, medial; D, lateral; E, proximal; F, distal. Abbreviations: ASM, articular surface for magnum; ASMC3, articular surface for third metacarpal; ASPP2, articular surface for proximal phalanx of the second digit; ASS1–2, articular surfaces for sesamoids 1–2; AST, articular surface for trapezoid; IR, intermediate relief; PR, posterior ridge. Scale bar = 5 cm. Figure 54. Right third metacarpal of ETMNH 609. Views: A, anterior; B, posterior; C, medial; D, lateral; E, proximal; F, distal. Abbreviations: ASM, articular surface for magnum; ASMC2, articular surface for second metacarpal; ASMC4, articular surface for fourth metacarpal; ASPP3, articular surface for proximal phalanx of third digit; ASS1–2; articular surface for sesamoids 1–2; ASU, articular surface for unciform; IR, intermediate relief; NF, nutrient foramen; PR, posterior ridge. Scale bar = 5 cm. 236 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) of the fifth metacarpal is fused to the fourth meta- carpal in place of the notch. At the distal end, the anterior articular surface for the proximal phalanx is smooth and proximally domed with only a slight lateral curvature. Two facets are on the posterior surface and are separated by an intermediate relief that slants from proximomedial to distolateral cre- ating slanted facets for articulation with the two sesamoids. Fifth Metacarpal.—Each manus of ETMNH 601 has a fifth metacarpal (Fig. 56) that was first described by Wallace (2006). A proximal articular surface for the unciform has a posterior convex fold. There is medial rugose bone that articulates with a proximolateral depression on the fourth metacarpal. On ETMNH 609 and 8271, the fourth metacarpals have expanded lateral knobs, which are believed to be the remnants of the fifth metacar- pals. Neither the isolated nor the fused fifth meta- carpals have evidence of a distal articular surface for a proximal phalanx. Though similar in morphology, metacarpals are noticeably larger than metatarsals (Fig. 57). Distal to the metacarpals, each digit consists of three phalanges and two sesamoids. Phalanges and sesamoids of the manus and pes are nearly indis- tinguishable except for by size (Fig. 58), so a com- bined description will be provided following the description of the hind limb. hinD limb Innominate.—It is difficult to differenti- ate the three bones—ilium, ischium, and pubis— that make up each innominate due to the degree of fusion (Fig. 59). The acetabulum is round with the acetabular incision on the lateral edge of the obturator foramen. There is a small fossa on the articular surface of the acetabulum. The ilium is the largest of the innominate bones and expands into a broad wing. Laterally, the iliac wing is smooth, but the medial iliac wing is rugose for articulation with the sacrum. The iliac crest is rounded at the dorsocranial spine and makes a nearly straight edge to the ventrocranial spine. A sciatic eminence is prominent on the dorsocranial spine and the greater Figure 55. Right fourth metacarpal of ETMNH 609. Views: A, anterior; B, posterior; C, medial; D, lateral; E, proximal; F, distal. Abbreviations: ASMC3, articular surface for third metacarpal; ASPP4, articular surface for proximal phalanx of fourth digit; ASS1–2, articular surfaces for sesamoids 1–2; ASU, articular surface for unciform; IR, intermediate relief; RMC5, remnant of fifth metacarpal. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 237 sciatic notch is deep. A thin, smooth ischium forms the symphysis, which is small relative to the over- all size of the innominate. The ischial arch occurs between this symphysis and the rugose ischiatic tuberosity. There is no evidence of an ilio-pubic eminence between the ilium and the pubis, which has a broad body and slender branches. Femur.—The diaphysis is slightly curved in the parasagittal plane (Fig. 60). The posterior sur- face of the femur is nearly flattened, but the ante- rior surface is more rounded. At the proximal end, there is a minimal trochanteric fossa along the pos- terior edge of the greater trochanter. A round artic- ular head extends only minimally proximal to the greater trochanter. Along the medial edge, the head forms a lip that overlies the suture line. There is no obvious fovea capitis on the femoral head. A shal- low depression is the only evidence of a femoral neck between the head and the greater trochanter. There is a blunt greater trochanter without a definite summit and with only a minimal crest at the latero- distal point. There is an elongate, rugose lesser tro- chanter on the medial surface that does not extend more medially than the femoral head. An elongate third trochanter is on the lateral surface but does not extend as far laterally as the greater trochanter. Figure 56. Right fifth metacarpal of ETMNH 601. Views: A, anterolateral showing articulation with fourth metacarpal; B, dorsal; C, medial; D, lateral. Abbreviations: ASU, articular surface for unciform; MC4, fourth metacarpal; MR, medial rugose bone. Scale bar = 5 cm. 238 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) lear tubercle along the diaphysis to the head. In anterior view, the more prominent medial troch- lear tubercle is also more rounded compared to the smaller and more angular lateral trochlear tubercle. It is possible that this medial trochlear tubercle acted as a locking mechanism as found in derived equids (Hermanson and MacFadden, 1996). On the posterodistal surface, a larger lateral condyle slants slightly compared to the smaller medial condyle, which is more aligned with the diaphyseal axis. A deep intercondylar fossa extends medially and lat- erally beneath the edges of the articular condyles. Both epicondyles have large muscle scars on the outer surface. Most femoral muscle attachments are well-defined, especially the supracondylar fossa on the posterior surface just proximal to the condyles. Patella.—Patellae are massive, rugose bones that articulate with the femoral trochlear tubercles (Fig. 61). A distinct point is formed by the apex at the distal end, but the base forms a rounded angle at the proximal end. The base does not extend much further proximally than the posterior articular sur- face does. This articular surface covers nearly the entire posterior surface and has two convexities The third trochanter is reduced among rhinocero- tids but is larger than those seen in most other spe- cies of Teleoceras. Distally, medial and lateral trochlear tuber- cles are present on the anterior surface and are sep- arated by a trochlear groove. There is a pronounced femoral ridge that extends from the medial troch- Figure 57. Right metapodials of ETMNH 609 in anterior view. A, metacarpals; B, metatarsals. Scale bar = 5 cm. Figure 58. Right phalanges of third digits of ETMNH 609. Left, front phalanges; Right, hind phalanges. A, proximal phalanges; B, medial phalanges; C, distal phalanges. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 239 Figure 59. Left innominate of ETMNH 609. Views: A, anterodorsal; B, anteroventral. Abbreviations: ACE, acetabulum; ACI, acetabular incision; DCS, dorsocranial spine; GSN, greater sciatic notch; ILC, iliac crest; ILW, iliac wing; IST, ischiatic tuberosity; OBF, obturator foramen; SYM, symphysis; VCS, ventrocranial spine. Scale bar = 10 cm. that extends from proximal to distal for articulation with the femoral trochlear tubercles. A rounded lat- eral angle is present but not pronounced. In con- trast, the medial angle is a well-defined prominence that forms a distomedial point. Tibia.—The proximal end is larger than the distal and, for articulation with the femur, it has two large articular surfaces separated by a minimal popliteal notch on the posterior surface (Fig. 62). The lateral articular surface is a rounded triangle whereas the medial articular surface is smaller, more rounded, and more centrally depressed than the lateral articular surface. A cranial intercondy- lar area is present between the anterior portions of the medial and lateral articular surfaces. A nar- row depression—the central intercondylar area—is bordered by the lateral and medial intercondylar eminences to separate the lateral articular surface from the medial articular surface and. There is also a smaller, flatter caudal intercondylar area between the posterior portions of the articular surfaces. Between the medial and lateral tibial tuberosities, there is a shallow tibial tuberosity groove. Though the medial tibial tuberosity is slightly rugose and aligned with the diaphysis, the lateral tibial tuberos- ity is more prominent, more rugose, and protrudes laterally from the diaphysis. Proximolaterally, there is a fibular articular surface that is shaped like an upside-down teardrop as seen on ETMNH 609. Rather than being smooth as most articular sur- faces are, this is rugose for a tight articulation that becomes fused with age as seen on ETMNH 601. In cross-section, the diaphysis is triangular as the tibial crest extends for nearly the entire length of the bone. The medial side of the diaphysis is nearly straight, but the lateral side is concave with a slight projection near the midpoint of the diaphy- sis. Distally, there is a parallelogram-shaped articu- 240 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Fi gu re 6 0. R ig ht fe m ur o f E TM N H 6 09 . V ie w s: A , a nt er io r; B , p os te rio r; C , m ed ia l; D , l at er al ; E , p ro xi m al ; F , d is ta l. A bb re vi at io ns : A H , ar tic ul ar h ea d; F R D , f em or al ri dg e; G RT , g re at er tr oc ha nt er ; I C F, in te rc on dy la r f os sa ; L C D , l at er al c on dy le ; L EC , l at er al e pi co nd yl e; L ET , le ss er tr oc ha nt er ; L TT , l at er al tr oc hl ea r tu be rc le ; M C D , m ed ia l c on dy le ; M EC , m ed ia l e pi co nd yl e; M TR , m ed ia l t ro ch le ar r id ge ; M TT , m ed ia l t ro ch le ar tu be rc le ; N K , n ec k; T F, tr oc ha nt er ic fo ss a; T G , t ro ch le ar g ro ov e; T H T, th ird tr oc ha nt er . S ca le b ar = 1 0 cm . SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 241 lar surface for the astragalus. Depressions for the astragalar trochlea are slanted from anterolateral to posteromedial and are separated by a raised ridge that appears to be pinched anteroposteriorly. Pos- teromedially to this articular surface is the medial malleolus, which is the distal-most point of the tibia. On the lateral surface, there is a small, domed articular surface for the fibula that contacts the astragalar facet along its distal edge. A triangle of rugose bone extends proximal to the fibular facet to form a tighter articulation with the fibula. A ridge connects the proximal and distal fibular facets as it runs the length of the diaphysis, including the lat- eral projection that matches the medial protuber- ance of the fibula. Fibula.—Fibulae have rugose ends with an Figure 62. Right tibia of ETMNH 609. Views: A, anterior; B, posterior; C, medial; D, lateral; E, proximal; F, distal. Abbreviations: ADP, anterodistal process; ASA, articular surface for astragalus; ASF1–2, articular surfaces for fibula 1–2; CDIA, caudal intercondylar area; CRIA, cranial intercondylar area; CTIA, central intercondylar area; LASF, lateral articular surface for femur; LIE, lateral intercondylar eminence; LTT, lateral tibial tuberosity; MASF, medial articular surface for femur; MIE, medial intercondylar eminence; MM, medial malleolus; MTT, medial tibial tuberosity; PN, popliteal notch; TCT, tibial crest; TTG, tibial tuberosity groove. Scale bar = 10 cm. Figure 61. Left patella of ETMNH 609 flipped to appear as right. Views: A, posterior; B, anterior. Abbreviations: AP, apex; BA, base; CV1 and CV2, patellar convexity 1 and 2; MA, medial angle; PAS, posterior articular surface. Scale bar = 5 cm. 242 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) distal to a corresponding projection on the lateral side of the tibial diaphysis. The fibulae of ETMNH 601 are proximally fused to the tibiae as seen in some species of Teleoceras (Prothero, 2005). Calcaneum.—The calcaneum is the largest of the tarsal bones (Figs. 64, 65). It is important to note that the articular surfaces of the calcanea display a large amount of variation in their size and shape. Heavily rugose bone covers the distal end of the calcaneal tuber and forms a ridge along the lat- eral surface of the diaphysis, which appears com- pressed mediolaterally. On the medial surface, the sustentaculum is prominent and rugose with only a slight tendon groove. A dorsal, roughly rounded articular surface for the astragalus is present on the sustentaculum. Lateral to the sustentaculum is a second articular surface for the astragalus. This facet is ovate, slants toward the sustentaculum, and is depressed along a mediolateral fold. The lat- eral edge of this articular surface folds over into a variably-shaped fibular articular surface. There is a small knob of rugose bone lateral to the fibular facet. On the medial side of the proximal process, there is a small facet that articulates with the astrag- alus. This facet folds into the oval articular surface for the cuboid on the plantar side of the calcaneum. Astragalus.—The proximal side of the astragalus forms a trochlea that provides the articu- lar surface for the tibia (Figs. 64, 66). The larger, lateral portion of the trochlea extends more proxi- mally than the smaller, medial portion. A wide trochlear groove separates the lateral and medial portions of the trochlea. The articular surface of the lateral trochlea folds posterolaterally to form a second proximal articular surface that, with the calcaneum, contributes to an articular surface for the fibula. The astragalar base is distal to the troch- lea and has two articular surfaces separated by a raised ridge. Medially, there is a square surface with rounded medial corners for articulation with the navicular. The lateral articular surface for the cuboid is rectangular with the long axis oriented anteroposteriorly, is nearly flat at the level of the ridge formed with the medial articular surface, and folds proximolaterally. On the posterior surface of the astragalus, there is an oval articular surface for anteroposteriorly compressed proximal end of the diaphysis and a triangular distal end of the diaphysis with rounded angles (Fig. 63). The proximal artic- ulation site for the tibia is shaped like an upside- down teardrop, whereas the distal articulation site is semi-circular. A small, round articular surface is present on the distal lateral malleolus for articula- tion with the astragalus. It is continuous with the corresponding distolateral articular facet on the tibia. A ridge curves from the proximal posterolat- eral articulation site to the distolateral articulation site. Along this ridge, there is a small protuberance that, when articulated with the tibia, is only slightly Figure 63. Left fibula of ETMNH 609 flipped to appear as right. Views: A, lateral; B, medial. Abbreviations: ASA, articular surface for astragalus; AST1–2, articular surfaces for tibia 1–2; LML, lateral malleolus. Scale bar = 10 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 243 Figure 64. Articulated right tarsal bones of ETMNH 609 in anterior view. Abbreviations: AST, astragalus; CAL, calcaneum; CUB, cuboid; ECC, ectocuneiform; NAV, navicular. The mesocuneiform and entocuneiform are not visible in this view. Scale bar = 10 cm. 244 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Figure 65. Right calcaneum of ETMNH 609. Views: A, dorsal; B, ventral; C, medial; D, lateral; E, distal. Abbreviations: AP, anterior process; ASA1–3, articular surfaces for astragalus 1–3; ASC, articular surface for cuboid; ASF, articular surface for fibula; CTB, calcaneal tuber; SUS, sustentaculum; TG, tendon groove. Scale bar = 5 cm. Figure 66. Left astragalus of ETMNH 609 flipped to appear as right. E and F are the right astragalus of the same specimen. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASC, articular surface for cuboid; ASF, articular surface for fibula; ASN, articular surface for navicular; ASS, articular surface for sustentaculum; AST, articular surface for tibia; BAS, base; DASCL, distal articular surface for calcaneum; DR, distal ridge; PASCL, proximal articular surface for calcaneum; TRG, trochlear groove; TRO, trochlea. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 245 the sustentaculum of the calcaneum that is posi- tioned superior to the midpoint of the base and inferior to the trochlear groove. Laterally, there is a large, oblong articular surface for the calcaneum proximolateral to the astragalar base. Navicular.—In general, the navicular is a square bone and is compressed proximodistally (Figs. 64, 67). One articular surface for the astraga- lus covers nearly the entire proximal side. This surface slants from the posteromedial corner to the anterolateral corner. At its anterolateral corner, this articular surface folds into a small, lateral articu- lar surface for the cuboid. There is another small, round articular surface on the posterolateral side that forms a second articulation with the cuboid. The two lateral articular surfaces are separated by a depression, but both form an edge with the distal articular surface. There is a small medial protuber- ance on the posterior surface with a small, round, distal articular surface for the entocuneiform. Dis- tally, the smaller, round, medial articular surface for the mesocuneiform is separated from the larger, triangular, lateral articular surface for the ectocu- neiform by a slight ridge. There is a concavity on the lateral edge of the ectocuneiform articular sur- face that corresponds to the depression between the lateral cuboid articular surfaces. Cuboid.—This bone is compressed proxi- modistally but is elongated anteroposteriorly (Figs. 64, 68). A nearly triangular portion extends into a posterior, rugose process with a distal curvature. On the medial side of the posterior process, there Figure 67. Right navicular of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASA, articular surface for astragalus; ASC1–2, articular surfaces for cuboid 1–2; ASEC, articular surface for ectocuneiform; ASEN, articular surface for entocuneiform; ASM, articular surface for mesocuneiform; MPT, medial process. Scale bar = 5 cm. 246 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) is a single anteromedial articular surface divided into two semi-circular facets. The proximal sur- face articulates with the navicular and the distal articulates with the ectocuneiform. Two articular surfaces are present on the proximal surface of the anterior portion; both are triangular and are divided by a ridge. The medioproximal articular surface articulates with the astragalus and the lateroproxi- mal articular surface articulates with the calca- neum. A small, proximal articular surface for the navicular is on the medial surface of the anterior portion. Distal to this facet is a domed articular sur- face for articulation with the ectocuneiform. This facet folds onto the distal surface into two artic- ular surfaces that are separated by a slight ridge. The smaller medial articular surface for the third metatarsal is a slender rectangle with the long axis oriented anterolateral to posteromedial. Laterally, a larger, triangular articular surface is present for articulation with the fourth metatarsal. Entocuneiform.—This is a small, rugose bone that curves distolaterally (Fig. 69). An oval anterolateral surface articulates with the mesocu- neiform and a small round proximal surface articu- Figure 68. Right cuboid of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASA, articular surface for astragalus; ASC, articular surface for cuboid; ASN1–2, articular surfaces for navicular 1–2; ASE1–2, articular surface for ectocuneiform 1–2; ASMT3, articular surface for third metacarpal; ASMT4, articular surface for fourth metacarpal. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 247 lates with the navicular. Mesocuneiform.—A rugose knob is present on the anteromedial face of the mesocuneiform (Fig. 70). The mesocuneiform proximally articu- lates with the navicular and distally with the sec- ond metatarsal. From the distal articular surface, the lateral edge folds proximally into an articular surface for the ectocuneiform. Also from the dis- tal articular surface, the posteromedial edge folds proximally into an articular surface for the entocu- neiform. Articular surfaces of the mesocuneiform are extremely variable in size and shape. Ectocuneiform.—A raised, rugose knob is present on the anterior surface of the ectocuneiform (Figs. 64, 71). There is a concavity just posterior to the midpoint on the lateral edge that corresponds to the concavity on the lateral edge of the navicu- lar. Proximally, there is one articular surface for the navicular that covers nearly the entire surface and has both the posterior and medial corners turned proximally. On the posterior portion of the proxi- mal surface, an edge is formed with the slender, elongate, lateral articular surface for the cuboid. There is a small, semi-circular articular surface on the posteromedial edge for articulation with the mesocuneiform. This articular surface folds distally into a rectangular articular surface for articulation with the second metatarsal. The articular surface for the second metatarsal forms a lateral edge with the distal, triangular articular surface for the third metatarsal. On the lateral edge, this distal articular surface forms an anterolateral edge with a second, round articular surface for the cuboid. On the ecto- cuneiforms of ETMNH 601, the more anterior of the two cuboid articulations is also in contact with the proximal navicular articular surface. Second Metatarsal.—There is a small rugose prominence on the anterolateral side of the distal end and a second rugose knob on the posterior sur- face (Fig. 72). Three articular surfaces are pres- ent on the proximal end of the second metatarsal. Medially, there is a round articular surface for the mesocuneiform. This facet forms a medial edge with a posteriorly rounded, rectangular proximo- lateral articular surface for the ectocuneiform. On the lateral side of the proximal end, the ectocunei- Figure 69. Right entocuneiform of ETMNH 609. Views: A, anterolateral; B, posteromedial. Abbreviations: ASM, articular surface for mesocuneiform; ASN, articular surface for navicular. Scale bar = 1 cm. Figure 70. Right mesocuneiform of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASEC, articular surface for ectocuneiform; ASEN, articular surface for entocuneiform; ASMT2, articular surface for second metatarsal; ASN, articular surface for navicular. Scale bar = 1 cm. 248 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) form facet forms an edge with a small, triangular articular surface for the third metatarsal. Distally, the anterior articular surface for the proximal pha- lanx is smooth and angled distomedially from the anterolateral prominence. On the posterior surface, the distal articular surface is divided into two fac- ets by the intermediate relief, which is aligned with medial rugose bone along the posterior surface. The facets slant proximomedially and each articu- lates with a sesamoid. Third Metatarsal.—The proximal end is posi- tioned slightly posterior to the distal creating the slant seen in the articulated pes (Fig. 73). Nutrient foramina are near the anterior and posterior mid- points on the third metatarsals. On the proximo- medial surface, a slender articular surface extends anteroposteriorly for the second metatarsal. The proximal edge of this surface contacts the larger, rectangular proximolateral articular surface for the ectocuneiform. A raised ridge occurs between the proximolateral articular surface and the nar- row, proximomedial articular facet for the cuboid. On the lateral side of the proximal end, there is Figure 71. Right ectocuneiform of ETMNH 609. Views: A, anterior; B, posteromedial; C, proximal; D, distal; E, medial; F, lateral. Abbreviations: ASC1–2, articular surfaces for cuboid 1–2; ASM, articular surface for mesocuneiform; ASMT2, articular surface for second metatarsal; ASMT3, articular surface for third metatarsal; ASN, articular surface for navicular. Scale bar = 5 cm. Figure 72. Right second metatarsal of ETMNH 609. Views: A, anterior; B, posterior; C, medial; D, lateral; E, proximal; F; distal. Abbreviations: ALP, anterolateral process; ASEC, articular surface for ectocuneiform; ASM, articular surface for mesocuneiform; ASMT3, articular surface for third metatarsal; ASPP2, articular surface for proximal phalanx of second digit; ASS1–2, articular surfaces for sesamoids 1–2; IMR, intermediate relief. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 249 an articular surface for the fourth metatarsal that has two rounded portions—anterior and posterior. A straight proximal edge contacts the lateral edge of the proximal cuboid articular facet. At the distal end of the third metatarsal, paired, round rugosi- ties are on the anterior surface and extend distally around their respective edges forming rugosities on either side. There is no distinct ridge along the midline of the posterior side of the diaphysis as on metapodials of other species, but there is a slight pair of depressions proximal to the distal facets. The anterior articular surface for the proximal pha- lanx is smooth and domed proximally with edges that are variable in shape. Posteriorly, an inter- mediate relief that is slanted slightly laterally as it extends proximally separates the distal articular surface into two facets that each articulate with one sesamoid. Fourth Metatarsal.—The lateral edges of the fourth metatarsals appear pinched anteropos- teriorly (Fig. 74), and ETMNH 609 has a slight inward curvature that is more pronounced than that of ETMNH 601. On the posterior surface, there is a rugose bump at the proximal end along the mid- line of the diaphysis. Only two articular surfaces are on the proximal end of the fourth metatarsal. A slightly depressed triangular facet covers the proximal surface for articulation with the cuboid. The straight medial edge of this facet forms an edge with the medial articular surface for the third metatarsal. This facet consists of two rounded por- tions—anterior and posterior. The posterior portion forms a process that extends posteriorly, and the anterior articular surface, which articulates with the proximal phalanx, is smooth and domed proxi- mally with a slant from proximomedial to disto- lateral. An intermediate relief divides the posterior articular surface of the distal end into two facets that each articulate with one sesamoid. PhAlAnges AnD sesAmoiDs Because the phalanges and sesamoids of the Figure 73. Right third metatarsal of ETMNH 609. Views: A, anterior; B, posterior; C, medial; D, lateral; E, proximal; F, distal. Abbreviations: ASC, articular surface for cuboid; ASEC, articular surface for ectocuneiform; ASMT2, articular surface for second metatarsal; ASMT4, articular surface for fourth metatarsal; ASPP3, articular surface for proximal phalanx of the third digit; ASS1–2, articular surfaces for sesamoids 1–2; IR, intermediate relief; NF, nutrient foramen. Scale bar = 5 cm. 250 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) manus and pes are so similar (Fig. 58), they will be described together. Phalanges and sesamoids of the second and fourth digits are larger in the manus than in the pes. In the third digits, the phalanges and sesamoids of the manus are approximately the same sizes as those in the pes. Typical of Teleoc- eras, the phalanges are compressed so the second and fourth digits are longer than the third to sup- port the digitigrade splay of the manus and pes. In the manus and pes, the third digit is the most com- pressed. It is important to note that, on the second digit of the left pes of ETMNH 601, the phalanges are pathological so that the distal and medial pha- langes are completely fused and the proximal pha- lanx is remodeled (Fig. 75). Proximal Phalanges.—Phalanges of the sec- ond and fourth digits are nearly mirror images of each other and are blocky with heavy rugosities on the non-articular surfaces (Fig. 76). Distally, these phalanges slope anteriorly so that the pos- terior edge is positioned superior to the anterior edge. Shapes of the articular surfaces are variable within and between individuals; proximal articular surfaces vary between round and square whereas distal articular surfaces are more ovate with a small concavity in the center and a notch on the poste- rior edge. Proximal phalanges of the third digits are more compressed anteroposteriorly but wider mediolaterally. Medial Phalanges.—Medial phalanges are much more compressed than the proximal pha- langes and have rugosities present on every non- articular surface (Fig. 77). However, like with the proximal phalanges, the medial phalanges of the second and fourth digits are nearly mirror images of each other. In anterior view, these phalanges are domed proximally. Like with the proximal phalan- ges, the shapes of the articular surfaces are variable within and between individuals; proximal articular surfaces are more ovate whereas the distal articular surfaces are convex anterior to posterior and just barely curve over the anterior edges. Medial pha- langes of the third digits are more compressed than those of the second and fourth digits. Distal Phalanges.—All of the distal phalan- ges are rugose and porous to allow blood vessels Figure 74. Right fourth metatarsal of ETMNH 609. Views: A, anterior; B, posterior; C, medial; D, lateral; E, proximal; F, distal. Abbreviations: ASC, articular surface for cuboid; ASMT3, articular surface for third metatarsal; ASPP4, articular surface for proximal phalanx of digit four; ASS1–2, articular surfaces for sesamoids 1–2; IR, intermediate relief. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 251 Figure 75. Pathological phalanges of the left hind second digit of ETMNH 601 with healthy phalanges of the right hind second digit. Notice that the left medial and distal phalanges are fused together. Abbreviations: DP, distal phalanx; MP, medial phalanx; PP, proximal phalanx; MT2, second metatarsal. Scale bar = 10 cm. 252 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) to reach the hoof structure (Fig. 78; Engiles et al., 2015). Distal phalanges of the second and fourth digits arc medially and laterally, respectively, and narrow to a point giving them a triangular appear- ance. Shapes of the proximal articular surfaces are variable within and between individuals, but tend to be round to ovate and slightly raised along the anterior edge. Sesamoids.—All of the sesamoids are rugose bones with concave articular surfaces for articula- tion with the metapodials (Fig. 79). DISCUSSION The occurrence of Teleoceras aepysoma in the Appalachian Mountains is unique within a genus typically found in the Great Plains (Prothero, 2005). Figure 76. Proximal phalanges of the right manus of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal. Abbreviations: II, second digit; III, third digit; IV, fourth digit. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 253 It is possible this unusual habitat contributed to the atypical morphology. For example, though the GFS population has many of the characters previ- ously described as typical of Teleoceras, it lacks features that can now no longer be used as syn- apomorphies for the genus (Table 3). Specifically, Teleoceras aepysoma exhibits, as adults: unfused nasals without a nasal horn and a less rotund body with longer, more gracile limbs. Limb elements of Teleoceras aepysoma are considerably elongated, which is noteworthy in a genus characterized by “short, robust limbs” (Prothero, 2005:94). Elon- gated limb bones during the late Hemphillian are also in contrast to the trend toward an increased “shortening and stumpiness” of Teleoceras limbs postulated by Prothero (2005:207; Fig. 80). These proportional differences are accompanied by other skeletal and dental characters that differentiate the GFS taxon and warrant the designation of a new species of Teleoceras. There are also unusual char- acters that are not true apomorphies, such as the presence of fifth metacarpals on ETMNH 601 and p2s on ETMNH 609 and 21659. Difficulties encountered while trying to clas- Figure 77. Medial phalanges of the right manus of ETMNH 609. Views: A, anterior; B, posterior; C, proximal; D, distal. Abbreviations: II, second digit; III, third digit; IV, fourth digit. Scale bar = 5 cm. 254 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) sify Teleoceras aepysoma make it clear that the genus Teleoceras should be revised. For instance, Prothero (2005:94) describes the nasal incision as “retracted to anterior P3” as a Teleoceratini syn- apomorphy, but this feature appears to be defined incorrectly because most, if not all, Teleoceras crania, including those from the GFS, have a nasal incision that extends posterior to the P3. The pres- ence of the GFS population illustrates the wide- degree of genus-level variation and brings atten- tion to the necessity of reexamining previously known populations for similarly variable character states. Because of the small sample size of the GFS specimens, no robust statistical analyses were per- formed. These analyses will be possible following further excavation of the site and recovery of addi- tional elements. Although Madden and Dalquest (1990:266) discussed potentially “the last rhinoceros in North America” from Blancan sediments in Texas, this is only a small, isolated tooth fragment identified as Teleoceras based on size, and it is possible that Figure 78. Distal phalanges of the right manus of ETMNH 609. Views: A, anterior; B, proximal. Abbreviations: II, second digit; III, third digit; IV, fourth digit. Scale bar = 5 cm. Figure 79. Posterior view of sesamoids articulated with the fourth metacarpal. Scale bar = 5 cm. SHORT ET AL.: A new late Hemphillian rhinoceros from Tennessee 255 it may have been reworked (Prothero, 2005). Gus- tafson (2012) made similar claims about an early Blancan Teleoceras tooth from Washington with similar reworking potential. Until more material is found, these specimens do not justify extending the temporal range of Teleoceras beyond the end of the Hemphillian. Therefore, the Gray Fossil Site can be added to the latest Hemphillian localities that contain the last of the North American rhinos: the Mount Eden Fauna of California, USA; the Yepómera (Rincon) Fauna of Chihuahua, Mexico; the Rancho El Ocote Fauna of Guanajuato, Mex- ico; and the Palmetto Fauna of Florida, USA (Ted- ford et al., 2004; Webb et al., 2008). ACKNOWLEDGEMENTS The authors would like to thank the numerous museum staff, students, and volunteers who were involved in this work from the discovery of the fos- sils to the publication of this manuscript. We thank J. Mead and B. Schubert for their comments on a previous version of this manuscript. A. Joyner pro- vided an initial map, and B. Compton, S. Haugrud, and A. Nye provided research assistance at the Gray Fossil Site. Additionally, we are especially grateful for the access provided to museum collec- tions by J. Galkin (AMNH), R. Hulbert (FLMNH), C. Ito (NMNH), L. Ivy (DMNS), and L. Wilson (FHSM). Finally, the authors thank K. Jansky, L. Burns, S. Cox, and J. Martin for their support of this research. This research was supported by a National Science Foundation grant to S. Wallace and B. Schubert (EAR-0958985), the ETSU Office of Research and Sponsored Programs, the ETSU Department of Geosciences, and the Don Sun- dquist Center of Excellence in Paleontology. LITERATURE CITED Anderson, J. F., A. Hall-Martin, and D. A. Russell. 1985. Long-bone circumference and weight in mammals, birds and dinosaurs. Journal of Zoology 207:53−61. Barone, R. 1999. Anatomie Comparée des Mam- mifères Domestiques, Tome 1: Osteologie. Figure 80. Ratios of length to midshaft width of humerus, radius, femur, and tibia. Except Teleoceras aepysoma, all measurements are from Prothero (2005). Teleoceras guymonense is excluded because of lack of data. 256 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Vigot Freres, Paris, 761 pp. Christiansen, P. 2002. 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All other data are from Prothero (2005: tables 4.9, 4.10, 4.11, 5.7, 5.8, 5.9). T. a m er ic an um T. m ed ic or nu tu m T. m er id ia nu m T. m aj or T. b ra ch yr hi nu m T. fo ss ig er T. p ro te ru m T. h ic ks i T. g uy m on en se T. a ep ys om a Skull P2 to occiput 444 482 -- 471 428 -- 475 511 -- 519.76 lambdoid crest to nasals 435 488 -- 483 403 -- -- 490 -- 455.49 width at zygoma 320 350 323 333 353 355 -- 356 -- 357.18 width of occiput 163 200 170 209 200 207 184 226 -- 235.61 height of occiput 161 239 -- 203 180 217 210 198 -- 196.54 Dentition P2–M3 227 236 -- 243 256 305 328 254 -- 265.99 P2–P4 97 94 -- 99 109 129 104 100 -- 116.29 M1–M3 136 140 138 143 149 178 150 152 159 158.85 p3–m3 210 242 -- 220 243 250 242 241 -- 246.84 p3–p4 72 72 -- 71 83 79 82 72 -- 82.33 m1–m3 141 155 -- 148 165 173 159 172 140 165.74 Humerus Length -- 333 264 314 311 307 284 315 -- 392.5 Distal Width -- 101 88 97 83 99 91 99 -- 154.1 Midshaft Width -- 56 48 67 54 61 61 65 -- 76.08 Ulna Length 305 310 -- 293 294 260 262 279 270 389.3 Midshaft Width 29 41 -- 42 31 35 38 42 38 59.20 Radius Length 257 265 215 257 257 259 252 250 235 310.6 Distal Width 75 86 77 94 73 99 92 95 87 97.9 Midshaft Width 40 48 42 48 41 50 50 53 52 48.84 Metacarpal 3 Length 120 134 104 118 113 115 105 115 117 125.6 Proximal Width 39 51 44 49 42 52 50 51 54 69.8 Femur Length 340 433 398 384 396 440 392 440 -- 491.6 Distal Width 133 121 110 123 98 113 102 115 -- 134.4 Midshaft Width 51 67 64 69 53 76 61 71 -- 69.99 260 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 56(5) Appendix 1. Continued. T. a m er ic an um T. m ed ic or nu tu m T. m er id ia nu m T. m aj or T. b ra ch yr hi nu m T. fo ss ig er T. p ro te ru m T. h ic ks i T. g uy m on en se T. a ep ys om a Tibia Length 250 276 218 236 263 236 195 230 220 271.5 Distal Width 70 88 70 85 74 87 75 86 76 90.1 Midshaft Width 45 47 40 49 42 50 47 52 40 51.44 Calcaneum Length 85 105 -- 125 94 130 124 125 -- 140.2 Width at Sustentaculum 54 63 -- 74 55 78 70 74 -- 77.06 Metatarsal 3 Length 102 110 87 98 99 109 86 84 -- 105.2 Proximal Width 37 48 32 44 37 50 40 39 -- 54.3