FLORIDA BUI LETIN... MUS tuivi OF NATURAL HISTORYTM MAGNETOSTRATIGRAPHY AND PALEONTOLOGY OF WAGNER QUARRY, (LATE OLIGOCENE, EARLY ARIKAREEAN) BASAL ARIKAREE GROUP OF THE PINE RIDGE REGION, DAWES COUNTY, NEBRASKA F. Glynn Hayes L Vol. 47, No. 1-, pp. 1-48 2007 UNIVERSITY OF FLORIDA GAINESVILLE f The FLORIDA.MUSEUM'OF NATURAL HISTORY is, Florida?s state museum of natural history, dedicated to undelsfanding„presel:ving, and inteipreting biojogicali,divegs'ity-~'~ ··' Roads Major ~ Minor 3 Unpaved (f Streams - Permanant . _.. Intermittant - , 2 Miles Figure 1. Location map of study area and Wagner Quarry. 4 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1) Since its discovery, fossils have been collected intermit- Quarry was labeled on the cross section (Tedford et tently by joint teams from the American Museum of al. 1985: 340, Fig. 2, cross section C-C'). The local fau- Natural History and the University of Nebraska State nas collected from Wagner and other localities around Museum . Chadron were listed as containing : Heliscomys woodi, This study of the Wagner Quarry fossils , herein Kirkomys schlaikjeri, Sanctimus stuartae, Leidymys named the Wagner Quarry local fauna, is the first sys- blacki, Geringia mcgregori, Palaeolagus philoi, tematic description of a micromammal fossil fauna and Arretotherium, "Pseudocyclopidius (Leptauchenia) large mammal concentration from the Pine Ridge re- major, Pseudolabis , Nanotragulus, Hypertragulus, gion . Peterson ( 1907) described large mammals from Miohippus, and Diceratherium. On the basis of these the Pine Ridge Squaw Butte region, north of Harrison, taxa Wagner Quarry was correlated to the early Nebraska, but these were isolated finds. More signifi- Arikareean. Hunt (2001) later described a new species cantly, this is also the first paleomagnetic study of basal of Paradaphoenus, R tooheyi, in part based on a man- Arikaree Group rocks at Pine Ridge. Bailey's (2004) dible recovered from Wagner Quarry. This species is biostratigraphic study reported only faunal lists from the intermediate in morphology between an Orellan species localities. MacFadden & Hunt (1998) paleomagnetically and a later medial Arikareean species. sampled the upper Arikaree Group (Harrison Forma- The fauna from the quarry and the geology have tion; Anderson Ranch= "Upper Harrison" Formation, never been completely described until this report. Bailey [Hunt 2002]) and the middle (Monroe Creek of Hatcher (2004) presented a faunal list (Table 1: 87) from a nearby 1902) to lower Arikaree interval but did not sample most basal Arikaree locality, the Ridgeview If (UNSM local- of the lowest fluvial facies of the basal Arikaree at Pine ity Dw-121), that contains the same taxa of microfauna Ridge. Prothero sampled paleomagnetically the White as in the Wagner Quarry lf. Bailey's biostratigraphic River Group ofthe Pine Ridge region, but did not study correlation Of the Ridgeview If places it slightly older the Arikaree Group sediments (Tedford et al. 1996: than the Gering B-D faunas of the Wildcat Ridge, but Prothero & Whittlesey 1998). younger than the Wildcat Ridge "Brown Siltstone" (= lower Sharps Formation) that has produced the earliest HISTORY OF INVESTIGATION Arikareean taxa (Tedford et al. 1996; Tedford et al. Wagner Quarry was discovered and surface collected 2004). by R. Tedford and T Galusha in 1975 in a brief recon- As part ofa study on the correlation of the Arikaree naissance ofthe basal Arikaree Group around Chadron, Group of the Pine Ridge (Hayes 2004), the Wagner Nebraska. They returned several times over the next Quarry local fauna is described along with the magnetic decade and collected horse , rhino, camel, Nanotragulus, stratigraphy of the Wagner Quarry section. and oreodont material. Tedford believed the fossils rep- METHODSresented a lower Gering/Sharps equivalent fauna Some of the small mammals were identified through(Tedford, pers. comm., 2003). comparison with the Ridgeview lf (Bailey 2004), whichIn 1981 a joint team from the American Mu- contains abundant and more complete material ofmanyseum and the University of Nebraska returned to the of the smaller mammal taxa found in Wagner Quarry.site and collected a varied fauna, including a juvenile Pseudolabis skull (F :AM 141372) and an anthracothere Otherwise, mammals were compared with reference mandible (F:AM 141369). A second channel fill higher material in the University of Nebraska State Museum in the section (see Fig. 5), discovered by M. Skinner in collections, the Frick Collection at the American Mu- 1981 as well, also yielded material of leptauchenine seum ofNatural History, and with taxa discussed in ap- oreodonts and several species of rodents (e.g., propriate literature. Anatomical terminology follows that Palaeocastor, Geringia). Collection has continued un- of current literature reviews of the major taxonomic til present as erosion exposes more fossils both in the groups mentioned in systematic discussions. All mea- quarry and in the upper channel . The skull of Cedromus surements are in millimeters unless otherwise stated . savannae n. sp. (UNSM 48448) was discovered in 2001 Tooth measurements were taken at the base ofthe crown by S. David Webb. along the principal cusp axes. Words placed in quotes The fauna from Wagner Quarry was first men- are informal terms, uncertain, or represent outdated ter- tioned in the field trip guidebook for the 45'h annual SVP minology retained for purposes of discussions. Referred meeting by Tedford et al. (1985). They briefly described specimens are from Wagner Quarry unless otherwise the quarry along with other mammal fossils collected noted. Illustrations and photos oftaxa omit"I" as a speci- from the basal Arikaree deposits near Chadron. Wagner men designation because ofits resemblance to the num- HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska 5 upper fossil B channel 6 VI V - top channel VE, ,- base - --4:/Vt»49 Jia=*7:*=* -» Figure 2. Photographs of outcrops and measured Wagner Quarry section. See Figure 5 for stratigraphic position. A, Wagner Quarry, view to the North, top of channel marked by dashed line; B, stacked overbank deposits above Wagner Quarry, view to north, local unconformities marked by dashed lines: C, top of Wagner Quarry section showing overbank deposits and "top channel" sands, view to north, base of channel marked by dashed line, Dave Webb for scale; D, expanded view of "top channel" butte, view to northwest; E, close view of Wagner Quarry basal Arikaree sandstone , Cedromus skull in coarser channel sand , F, close view of Wagner Quarry channel cross bedded sand with lithic clasts. 6 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1) 0- ~DNAG Heamatite stained1 Ithic ~ CM IN - ripple stringe layer -... fosgilf ' *fielb n M I -... .-I + ./. ~ : 1 st riDDle layer Gpper fossn channel 4, - p-56-4=U:'=»i«4&/6 Ipt rip*~Si ~ tr.: rD'~" Figure 3. Photographs of outcrops and measured Wagner Quarry section. See Figure 5 for stratigraphic position. A, close view of clay and siltstone pebble clasts in Wagner Quarry channel; B, close view of hematite stained and cemented cross-beds in Wagner Quarry channel; C, close view of 1 »' ripple layer, above Wagner Quarry, showing local diastem marked by clay stringer; D, -upper fossil channel" and 2nd ripple layer. dashed line marks channel base: E, Wagner Quarry section showing 1 »z ripple layer below "upper fossil channel", sediments in between are interpreted as overbank deposits; F, close view of "upper fossil channel" showing fine scale laminae and small fossil burrows: a close view of large fossil burrow infilled with siltstone gravels and sand in "upper fossil channel". HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska 7 ber " j". Abbreviations.- (others defined in text, tables, or figures); ap, anterior to posterior measurement, length: apt, anterior to posterior measurement of trigonid on lower molars, length, F, Fauna; Fm, Formation; L. left; lf, local fauna; M, mean: m# or M#, molar, lower case for lower molar: N, number of specimens: OR, observed range of variation: p# or P#, premolar, lower case for fil ill--- I. -/ r - -1 lower premolar; R, right; tr, transverse measurement, width: tra, transverse measurement of anterior trigonid width in lower molars: trp, transverse measurement of .-46:We:/1/.,2,52:-:.~tj;;.li- 1 : \ posterior talonid width in lower molars. Institutional abbreviations.- AMNH, American Museum of Natural History, New York; F:AM, Frick 4: *i Mammal Collection of the American Museum ofNatu- ral History, New York; LACM, Los Angeles County Museum, Los Angeles, California; SDSM, South Da- r.- S:f, : 9*: ](Bll kota School of Mines, Rapid City, South Dakota; UC, University ofChicago collections. Field Museum, Chi- -.-r cago, Illinois: UCMP, University ofCalifornia Museum ofPaleontology, Berkeley, California; UF, University of Florida collections, Florida Museum ofNatural History, 414 Gainesville. Florida: UNSM, University ofNebraska State Museum, Lincoln, Nebraska; YPM, Yale Peabody hannMuseum, Yale University, New Haven, Connecticut. Base GEOLOGY The Wagner Quarry section consists of a stack of flu- viatile sediments, alternating between channel fill, bar deposits, and floodplain or over-bank deposits separated by local diastems that show slight pedogenic alteration 'I' at the top of many of the beds. The base of the measured Wagner Quarry section 53€35&- 4. <1$1 ' >2..(Fig. 2A) does not have a contact between the fluvial *El 6 UArikaree and the underlying "Brown Siltstone" (= lower ~ ~ Sharps) member ofthe Brule Formation. However, both - '.,/ --- ...'. .. - north and south of the Wagner Quarry on Dead Horse r 421~-2»'~ 7 Road, there are outcrops of Arikaree gray, cross-bed- 7 4 . I. KA... 1 im/EF ./.- . ded fine-medium sands unconformably overlying light pinkish to tan siltstones of the White River Group. The 1 \ southern contact outcrop exposes the Nonpareil Ash - 1.. f. I'll" i · - (NP) (Swinehart et al. 1985), approximately 6m topo- 1--mir \ 4 /. ..<8* - r: graphically below Wagner Quarry, as shown in Figure 5 - ff,' ·. Pedogeni¢ alteratidnl L '··. - ~ (Stratigraphic distance could not be determined due to ground cover). This ash in the Pine Ridge has been cor- related to the NP, ash (Tedford et al. 1996) that is ex- Figure 4. Photographs ofoutcrops and measured Wagner posed at Wildcat Ridge. This ash at Wildcat Ridge was Quarry section. See Figure 5 for stratigraphic position. dated using 4OAr/Arig to 30.05 +/- 0.19 Ma (Tedford et A, "top channel" sandstone butte showing eroded base al. 1996: Swisher & Prothero 1990). of channel and large scale bedding; B. close view of The base of the Wagner Quarry section is a chan- "top channel" base showing local incision; C, close view nel deposit of fine gray, trough cross-bedded epiclastic of top of overbank deposits showing mottling and clay sand and pebble conglomerates (Fig. 2F) with occasional clumping interpreted to be pedogenic alteration. 8 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1) Wagner Quarry Section Lithostratigraphy Legend Elevation (ft) · weakly cross-stratified ......:r·::;4:k : very fine to fine loosely 3955 i'}*ii}lilimi}E:g:gf~E}i} .: ::.'.:.:t: consolidated sandstone 1!} § SE }EEEii~EEE HiEZEEEiEEE :~::*:;:f: with dispersed pebble clay i:.....fi:EE clasts 6"*~ fine loosely consolidated sandstone with pebble size3945 ;::....:.:.1.1:::::::::::E::.:.... clay ciasts at base ri....-.-.7 massive very fine to r.':':':':':1 fine loosely consolidated--1----055/firin - Fig. 4, B ..... sandstone 3935 :53.6..6~.(.63:b.~--4/V'site, unused O Class 1 Reversal Site Figure.9. Lithostratigraphy and corresppnding Virtualv Geomagnetic Poles forjhe Wagner'Quarry secti'one (see Fig. 5 fdrilithol6gy'legend}. - 14 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1) Table 2. Wagner Quarry local fauna mammalian faunal not available in the section (although the NPZ is present list. close to the section, as mentioned in the geology sec- tion), a field stability test is not possible, and directions Mammalia were only partially determined by principal component Marsupialia analysis. The criteria fulfilled by this study include: 1)Herpetotherium fugax Insectivora stratigraphic age known to the level of Cenozoic stage, Ocajila makpiyahe 2) sampling localities placed in a measured stratigraphic Proscalops sp. section, 3 ) complete thermal orAF demagnetization per- Rodentia formed and vector analysis carried out using orthogonal Aplodontidae plots, 4) data published completely, 5) magnetic mineral- Downsimus chadwicki ogy determined, and 6) associated paleontology presented Alwooclia cf. A. magna Sciuridae adequately. The results show that even though the WagnerCedromus savannae n. sp. Nototamias sp. section is relatively short, there are three magnetozones Castoridae present (Fig. 9). From the base of the Wagner Quarry Agnotocastor sp . section up to the beds below the "upper fossil channel", Palaeocastor sp. 6 sites are of normal polarity. A short reversal , among Heteromyidae the otherwise normally polarized samples, is character- Proheteromys d. R ized by two Class I sites , although mean confidence lev- nebraskensis els were relatively dispersed for the sites (Fig. 7; Table Cricetidae 1). This probably indicates incomplete removal of a nor-Leidymys blacki Geringia mcgregori mal overprint, though the individual samples all showed Lagomorpha clear reverse polarity. Above the reversal, there is a Leporidae normal interval also characterized by two Class I sites. Palaeolagus hypsodus Palaeolagus philoi WAGNER QUARRY LOCAL FAUNA Megalagus cf. M. primitivus In addition to the mammal fauna, the non-mammalian Carnivora material includes sparse fish and snake vertebrae, an Amphicyonidae alligator premaxilla (UNSM 123224), turtle elementsParadaphoenus tooheyi* (UNSM 123234 nuchal plate, UNSM 123236, humerus), Canidae and sparse avian material (e.g.: UNSM 123449-123453). Canidae indet. The mammalian fauna is diverse considering that many Nimravidae taxa are represented by only a single specimen. The Nimravus brachyops fauna is also relatively unique in that it contains both Perissodactyla micro- and mega fauna. Most sites in the Pine Ridge or Equidae Wildcat Ridge are restricted, through taphonomic filters, Miohippus sp. to either small mammals or isolated occurrences of larger Rhinocerotidae mammals. Twenty-seven mammalian species areDiceratherium annectens Diceratherium armatum present, including a marsupial , 2 insectivores, 9 rodents, Artiodactyla 3 lagomorphs, 3 carnivores, 3 perissodactyls, and 6 ar- Entelodontidae tiodactyls (Table 2). Entelodontidae indet. Merycoidodontidae SYSTEMATIC PALEONTOLOGY Desmatochoerinae indet. Class MAMMALIA Linnaeus 1758 Leptauchenia major Order DIDELPHIMORPHIA (Gill 1872) Anthracotheriidae Family DIDELPHIDAE Gray 1821Bothriodontinae indet. Genus HERPETOTHERIUM Cope 1873Camelidae Pseudolabis dakotensis HERPETOTHERIUM FUGAX Cope 1873 Hypertragulidae Table 3 Nanotragulus loomisi * described by Hunt, 2001 Type.-AMNH 5254, R Ml -M4 (Cope 1884). Type Locality.-Cedar Creek Beds, White River HAYES:Magbet<*tr#figr#Hy@rdus, R loWet cheektaoth, oee'lusal, view. Scale bars = 1mm. 16 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1) Table 3 . Dental measurements for Herpetotherium fugax, rodents and Palaeolagus hypsodus (other small mam- mal taxa in text or separate table). Specimens are from Wagner Quarry lf unless otherwise stated. (Compiled from author's measurements; MacDonald, 1970; Rensberger, 1983; Wood, 1937.) H. fugax UNSM 123290 UNSM 123289 M3 ap 1.90 ml/m2 ap 1.80 tr 2.15 tra 0.99 «P 1.16 FM 141248 m3 ap 1.98 m4 ap 1.15 tr 1.17 tr 1.11 Downs imus UNSM 123285 chadwicki p4 ap 2 . 17 ml ap 2 . 13 m2 ap 2 . 14 m3 ap 2 . 35 tr 1.66 tr 1.62 tr 1.77 tr 1.74 LACM 17031 (type) Sharps Fm LACM 1959 Sharps Fm ml ap 1.83 m2 ap 1.90 m3 ap 2.41 tr 1.57 tr 1.70 tr 1.65 Alwoodia sp. UNSM UNSM UNSM UCMP 123400 81500 24088 76941 Wagner Monroe McCann Can. John Day Quarry Creek A. harkseni A. magnus (type) P4 ap 3.43 4.12 3.17 3.6 tr 3.84 4.18 3.26 3.75 Nototamias sp . UNSM 123293 ml ap 1.42 m2 ap 1.76 m3 ap 2.01 tr 1.34 tr 1.52 tr 1.56 trp 1.39 trp 1.63 trp 1.52 Palaeocastor sp. F :AM 141246 P4 ap 3.11 Ml ap 2.69 M2 ap 2.70 tr 4.87 tr 4.90-4.96 tr 4.43-4.76 F:AM 141246 F:AM 141245 UNSM 123284 M3 ap 2.65 p4 ap 4.99 M l or 2 ap 3.38 tr 3.27 tr 4.28 tr 4.16 Proheteromys UNSM 123281 cf. r ap p4 1.17 - - n13 1.37 nebraskensis tra 0 . 99 1 .48 trp 1.11 0.97 MCZ 5051 (holotype) Brule Fm ap p4 1.02 ml 1.24 m2 1.20 m3 1.08 tra 1.02 1.38 1.41 1.11 trp 1.11 1.42 1.27 0.98 HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska 17 Table 3. Continued Leidymys UNSM 123287 blacki ml ap 1 .67 m2 ap 1 . 55 m3 ap 1 . 53 tra 0.97 tra 1.26 tra 1.26 trp 1.18 trp 1.31 trp 1.08 FM 141248 Ml ap 2.02 M2 ap 1.63 M3 ap 0.95 tr 1.36 tr 1.42 tr 1.18 Geringia UNSM 123283 mcgregori ml ap 1 . 67 n12 ap 1 . 55 m3 ap 1 .53 tra 0.97 tra 1.26 tra 1.26 trp 1.18 trp 1.31 trp 1.08 UNSM 123286 ml ap 1.81 m2 ap 1.75 m3 ap 1.83 tra 1.21 tra 1.63 tra 1.59 trp 1.44 trp 1.69 trp 1.42 incisor ap 1.37 tr 1.24 Palaeolagus F :AM 141247 hypsodus ap p3 2 . 15 p4 2 . 69 ml 2 . 69 m2 2 . 67 m3 1 . 55 tr 1.67 2.44 2.46 1.45 1.45 Formation, Logan County Colorado. Referred Specimen.-UNSM 123291, L P4. Referred Specimens.-UNSM 123289, lower Discussion.-This tooth closely matches those in molar; UNSM 123290, R M3 ; F :AM 141249, L m3-4 . the large sarnple of Proscalops material from the Discussion.-Korth (1994b) reviewed North Ridgeview lf that Bailey (2004) identified as P. cf. P. American Tertiary marsupials and placed all Arikareean miocaenus . Measurements : ap = 2 . 17 , tr = 1 . 96 . Herpetotherium in H. youngi, diagnosing the species on the basis that upper molars possess a single central Family ERINACEIDAE Fisher von Waldheim 1817 stylar cusp . However, new material from the Ridgeview Genus OCAJILA Macdonald 1963 lf (=UNSM Dw- 121 ) (Bailey 2004) and from Florida OCAJILA MAKPIYAHE Macdonald 1963 (Hayes 2005) shows that early Arikareean Figure l OC-D Herpetotherium possesses a variable central stylar cusp morphology similar to H. fugax, an older species known Type.-SDSM 56105 , L ramus with m2-m3 . from Chadronian-Orellan NALMA deposits. Therefore, Type Locality.-SDSM V5360, Sharps Formation, Hayes (2005) extended the range of H. jugax into the early Arikareean. early Arikareean to encompass the Ridgeview lf and Referred Specimen.-UNSM 123288, R p4. Florida specimens. The small amount of material from Discussion.-Referral of this tooth is based on Wagner is the same size and morphology (possesses comparison with more complete dentitions from the multiple stylar cusps) as the Ridgeview lf Ridgeview lf, which were identified through comparison Herpetotherium and is referred to H. fugax. to a cast of the type . There is currently only one species assigned to the genus Ocajila, 0. makpiyahe. A single Order INSECTIVORA Illiger 1811 ml (UNSM 24166) described by Korth (1992) from the Family PROSCALOPIDAE Reed 1961 McCann Canyon lf is larger than any known for O. Genus PROSCALOPS Matthew 1909 makpiyahe and may be a younger second species . PROSCALOPS sp. Measurements : ap = 1 . 51 , tr = 1 . 04 Figure l OA-B Order RODENTIA Bowdich 1821 18 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1) Family APLODONTIDAE Trouessart 1897 Genus DOWNSIMUS Macdonald 1970 DOWNSIMUS CHADWICKI Macdonald 1970 #Fi'\ AS?855 Figure 13C; Table 3 ~~~)1~,t~ ~~~~*:*~*~ Type.-LACM 17031, partial R mandible, with ml-3. F*/ 7/0,31 Eyalm #Im Z -0$ 0 E (eN) 3011-1- ALIZ:IV-10d LUOJ-2 5 6 0- < I - Ul Z 01- 07r Gering Fm Wildcat Ridge 2626 C7A Roundhouse Rock pisolitic C8n ash 4OAr/39Ar _ 128.11 10.16 CBr ' Chimney Rock perrierite 27 ash 40Ar/39Ar 27Z = + 28.26 + 0.05 < , Twin Sisters Pumice \ LI-1 C9rl , - +Conglomerate 4OAr/39Ar ~ UJ 28.31+ 003 ~ - 28 ~ C9r ~ Wagner Q. Section 28 --- -- ClOn.ln 1111*Ii CE Clon.lr < Cl On.2n ---- --. 29 (1 Or ~ 'The Brown Siltstone" -Wildcat 29 Ridge Clln.ln ..Clln.lr , ........46...::::: 30 Clln.2n NP) 30.05+0,19 ~- 30 Cllr Z NP2 - LU < Z > C12n ... LU31 Ul Z 310t Or 09 3 C12r 3232 0 Z -1 33 W 33 ~0 C13n Figure 18. Correlation ofthe Wagner Quarry section to the Global Polarity Time Scale. (Berggren et al., 1995) HAYES: Magnetostratigraphy and Paleontology of the Wagner Quany, Nebraska 41 Be gg re n et 0 32E €5 ./.Vk.~. M a a/. , 1 99 5 :25 0 L93 ·5 0 0 & b * CiS .2 44 I 2 -§ 0 / i E P * E t .5 IE * § 0.t Q 0 W hi tn ey an l Ar ik ar ee an N AL M a 9 4 0 0 0 C & 2as£@5@~efs !slulool snin ® 2 gamE€ 5 C hr on Nebraska »~ui -§ 85*2.SEE5 85 z-5 5 5 8 §§ Pine Wildcat s 0600,0/3 . c. S 58* B.$22 OAE60O40 Ridge Ridge Dakotka-ZO0 ... Wagner '- Quarry 129 -r•-4><. C 1 Or Z E Lower I - 2 15 2 Shari)s 1? & 0 ++NP3+ 5 ++NP3+ 1riX E E ++NP2+ ++RF++ 2 - (DC 30 Z .. - 2 9 ++Npl+ - CllrI ~ Poleside Mbr 0 ++UW++- 6?2 Whitney Whitney Mbr Mbr Figure 19. Composite chronostratigraphic chart of selected taxa in Nebraska and South Dakota. (modified from Tedford et al., 1996) "Brown Siltstone in Pine Ridge is correlated using Toadstool Section (Tedford et al., 1996: Fig. 7:324). * Gering Fm dated ashes in Fig. 18. 42 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47(1) extended the range of Downsimus in the northern Great in the third phase there are practically no White River Plains into the late early Arikareean. The other aplodontid, taxa. Alwoodia, is listed by Tedford et al. (2004) as having its Some further discussion regarding the Kealey first appearance in the Great Plains during the late early Springs lf is warranted here given the above problems Arikareean. The recognition ofthis taxon in the Wagner with range extensions (e.g. Downsimus, Geringia, and Quarry If extends the range down into the early early also Nanodelphys) outside of the central Great Plains . Arikareean (Arl) for the Great Plains, which would agree The Kealey Springs lf was correlated to the late early with the genus' first appearance in the John Day region Arikareean (Ar2) and it is believed to be equivalent to at - 28.7 Ma. the "Monroe Creek" sediments in Nebraska (Storer 2002; Some of the larger taxa in Wagner lf are not as Tedford et al. 2004). Some of these problems may be restrictive in age determination in comparison to the small due to the fact that the Monroe Creek Formation of the mammals, but they do provide support for assignment to Pine Ridge and its equivalents in Nebraska have pro- the early Arikareean. Paradaphoenus tooheyi (Hunt duced little in the way of comparative fossils (Bailey 2001) is transitional between the Orellan P minimus and [2004] uses the South Dakota Wewela tf [Skinner et al. the late early to-"medial" Arikareean P cuspigerus . 1968] to represent this interval). However, the "Monroe Nimravus has its last appearance in the late early Creek" sediments of the Wildcat Ridge have yielded Ankareean (Tedford et al. 2004). The oreodonts belong several micro-mammal ant hill collections that have never to genera that are common to other early Arikareean been studied. The study of the Cedromus and Alwoodia localities in the Great Plains . Pseudolabis is a common material of this report indicates that some of the early camel in the Whitneyan and early Arikareean (McKenna Arikareean taxa could extend upward into the late early 1966) and is the beginning of the stenomyline radiation Arikareean and may more closely match the Kealey o f camels that became dominant in the later Arikareean Springs 1fthan previously thought. Preliminary study here of the Great Plains (Honey et al. 1998). indicates that the faunas contain mylagaulid rodents simi- Based on the definition and characterization ofthe lar to the Kealey Springs lf as well as cricetid rodents. early early Arikareean (Arl) as reported by Tedford et These "Monroe Creek Ant Hill" faunas should be fur- al . (2004), the presence of Nanotragulus loomisi, ther investigated to help refine the characterization of Agnotocastor, Geringia mcgregori, Leidymys blacki, the late early Arikareean in the central Great Plains . and Palaeolagus hypsodus firmly places the Wagner The basal Arikaree sediments and the overlying Quarry lf in this time period. None of the defining or Monroe Creek Formation in the Pine Ridge do not have first appearance taxa (except/ilwoodia) ofthe late early any radioisotopic dates at present. As mentioned previ- Arikareean (Ar2) such as Amphechinus, Parvericius, ously the Wagner Quarry section is in proximity to an Gripholagomys, Archaeolagus, Promylagaulus, outcrop of the Nonpareil Ash. This ash has been mag- Gregorymys, and Stenomylus are present in the Wagner netically correlated to the NP3 ash ofthe Wildcat Ridge fauna. (Tedford et al. 1996) which has been dated from out- Based on this study, which adds to the work of crops there (Swisher & Prothero 1990). At the Wildcat Tedford et al. (1996) and Bailey (2004), the early early Ridge, the Gering Formation and "Brown Siltstone" are Arikareean (Arl) can be resolved into three phases: the constrained in age by several radioisotopic dates (Tedford first phase of the early Arikareean is represented by the et al. 1996). The oldest of these ages is represented by faunas of, or equivalent to, the"Brown Siltstone" or lower the NP3 ash (30.05 +/- 0.19 Ma) in the upper part ofthe Sharps (BlueAsh lf, Martin 1974; Simpson 1985; Gering "Brown Siltstone". The youngest dated ash in the Gering A, Swisher 1982; lower Cabbage Patch faunas, Formation (Roundhouse Rock pisolitic ash) establishes Rasmussen 1977). This is followed by the next phase an upper boundary at 28.11+/- 0.18 Ma. Two other ashes exemplified by the Pine Ridge basal Arikaree faunas within the Gering further constrain the age of this for- from Wagner 1fand Ridgeview lf, and possibly the Gering mation: the Twin Sisters Pumice Conglomerate (28.31 B 1fof Swisher (1982). The upper Gering Formation(as 4-/- 0.03 Ma) near the base and the Chimney Rock defined by Swinehart et al. 1985) faunas and their equiva- perrierite ash (28.26+/- 0.05 Ma). lents in the upper Sharps represent a third phase. These Work in the Wildcat Ridge by D. Prothero (Tedford phases exhibit a step-wise tfansition ofchange between et al. 1996) has shown that fluvial basal Arikaree depos- White River taxa and taxa of the early Arikareean as its ofthe pumice-bearing Gering Formation are reversely suggested by Bailey (2004:104). The earliest phase fau- polarized at their base and do not change into normal nas retain c. 25% White River taxa. The faunas equiva- polarity until the uppermost part ofthe formation. Using lent to Wagner include only about 10% relict taxa; and the above geochronology, Prothero correlated the Gering HAYES: Magnetostratigraphy and Paleontology of the Wagner Quarry, Nebraska 43 Formation to the lower part of Chron 9 and the upper magnetic study of the basal Arikaree in the Pine Ridge. part ofthe "Brown Siltstone" to Chron 1 ln and part of These two studies provide a more accurate correlation Chron 1 Or (paleomagnetic time scale of Berggren et al. than was previously possible of the basal Pine Ridge 1995). "The Nebraska sections show a hiatus in Chron Arikaree Group to the basal Arikareean sediments in Cl Or with Chron C 10n missing" (Tedford et al. 1996:317). the Wildcat Ridge, as well as to early Arikareean sedi- The paleomagnetic results of the Wagner Quarry ments and faunas outside of Nebraska. The indepen- section show that most ofthe section is normally polar- dent paleomagnetic correlation shows that the initial basal ized, unlike the top of the "Brown Siltstone" or the ma- fiuvial deposition ofthe Pine Ridge Arikaree paleovalley jority ofthe Gering Formation. A single section ofnor- was not synchronous with the Gering Formation, Arikaree mal polarity in the Pine Ridge is not strong evidence that Group, deposition in the Wildcat Ridge. the basal Arikaree deposition there is entirely different The Wagner Quarry section represents a stack of from the Gering Formation. However, ·this normal sig- fluvial sediments, from main channel fills (Wagner nature is supported by the same polarity signature of the Quarry, the "upper fossil channel" and the "top chan- lithologically similar basal fluvial sediments exposed at nel"), through distal channel point bar deposits (uniform the bottom of the Monroe Creek Canyon section (the ripple layers), to flood plain or over-bank deposits that type section for Hatcher's [1902] Monroe Creek beds are separated by diastems when pedogenic alteration and Harrison beds) located to the east ofWagner Quarry took place. The fossils of Wagner Quarry represent a north ofHarrison, Nebraska (Hayes 2004). MacFadden relatively wet riparian environment that became increas- & Hunt (1998) correlated the base of their composite ingly drier by the time the "upper fossil chhnnel" was Arikaree section to Chron C9r (Berggren et al. 1995), deposited. Channel sediments become increasingly bet- similar to the Gering Formation, because they suggested ter sorted and mineralogically similar towards the top of that the fluvial sediments at the foot of the Pants Butte the section as indicated by less influx of allocthonous section represented the same interval as the Gering For- lithic material in the Wagner Quarry channel and re- mation in the Wildcat Ridge. In Monroe Creek Canyon working ofcompletely intraformational sediments in the there are considerable (- 4Om) Arikaree fluvial sedi- "top channel". ments, referred to above, that are not represented in the Comparison ofthe Wagner Quarry 1fto the faunas Pants Butte section and occur stratigraphically below of the Gering Formation, the "Brown Siltstone", the the cross-bedded sandstones at the bottom of the Pants Ridgeview lf, and the faunas of the Sharps in South Butte section. Dakota as well as to Tedford et al.'s (2004) defining and Faunal comparison with the Ridgeview lf and characterizing taxa of the early early Arikareean, place Gering faunas in Nebraska places the Wagner Quarry lf the Wagner 1fbiochronologically in this interval (Arl), firmly in the early Arikareean (Arl) or between 30-28 or approximately 30-28 Ma. Ma. Detailed comparison with the faunas of this inter- The Wagner Quarry section is predominantly mag- val and stratigraphic correlation with the Ridgeview tf netically normal. This is different from the Gering For- suggests an older age than the upper Gering faunas. mation in the Wildcat Ridge, which is mostly magneti- The Wagner Quarry section is constrained in its lower cally reversed and the "Brown Siltstone," which is also placement by the Nonpariel Ash 3 date. These param- reversed in its upper section. Faunal correlation places eters leave one normal chron of appropriate age that the Wagner Quarry in the early early Arikareean would fit the polarity signature of the Wagner Quarry NALMA, slightly older than the radioisotopically cali- Section- Chron 1On (Berggren et al. 1995). This cor- brated Gering Formation faunas and slightly younger than relation is also supported by the small reversal within the "Brown Siltstone" 1fs. This constrains the C IOn- C 1On.lr, which is probably represented in the magnetostratigraphy to Chron 100 (28.25-28.87 Ma, short reversal of the Wagner section (see Fig. 18). The Berggren et al. 1995). The section records the short basal Arikaree of the Pine Ridge therefore helps to fill reversal of C 1 On. l r. the gap in time that may not be recorded by sediments in Correlation using the Wagner lf and the Wagner the Wildcat Ridge and extend the range of several taxa Quarry magnetostratigraphy shows that there is a three into this interval. phase transition within the early early Arikareean. The first phase is characterized by the jocal faunas of the SUMMARY AND CONCLUSIONS "Brown Siltstone"; the second phase by the Wagner lf The Wagner Quarry fauna is the first large mammal and the Ridgeview lf; and the third by the Gering fau- concentration described from the historically important nas. Characteristic White River taxa become increas- Pine Ridge basal Arikaree Group and the first paleo- ingly rarer in each phase. 44 BULLETIN FLORIDA MUSEUM NATURAL HISTORY VOL. 47( 1) The recognition of a new species of Cedromus in ing, 1992:65. the Wagner lf and the assignment of the Gering Forma- Bailey, B. E. 1999. New Arikareean/Hemingfordian tion "Miospermophilus" (Martin 1973) to Oligo- micromammal faunas from western Nebraska and spermophilus extends the range of the Cedromurinae their biostratigraphic significance. Journal of Verte- brate Paleontology, 19:30A-31 A.into the early Arikareean . Alwoodia is also recognized Bailey, B. E. 2004. Biostratigraphy and biochronologyfor the first time in the early early Arikareean (Arl) of the central Great Plains. of early Arikareean through late Hemingfordian small mammal faunas from the Nebraska panhandle and ACKNOWLEDGEMENTS adjacent areas. Paludicola, 4:81-113. Berggren, W. A., D. V. Kent, C. C. Swisher, & M. R This study was produced as part of the author's disser- Aubry. 1995. A revised Cenozoic geochronology and tation research and was supported by funding from the chronostratigraphy. Pp. 129-212 in W. A. Berggren, University of Nebraska State Museum and the Depart- Kent, D. V., Aubry, M. R, & J. Hardenbol, eds. Geo- ment of Geosciences. My deepest appreciation is ex- chronology, Time Scales, and Global Stratigraphic tended to my advisor, Robert M. Hunt, Jr., who sug- Correlation: Tulsa, SEPM Special Publication 54. gested this study and answered years of questions and Black, C. C. 1963. A review of the North American made numerous suggestions for improvement. I thank Tertiary Sciuridae. Bulletin of the Museum of Com- Mike Voorhies, David Loope, and Patricia Freeman, for parative Zoology, Harvard, 130(3):110-248. their review of the manuscript in dissertation form. Ac- Bryant, N. H., 1996. Nimravidae. Pp. 453-475 in D. R. cess to the American Museum of Natural History col- Prothero & R. J. Emry, eds.The terrestrial Eocene- lections was granted by Richard Tedford who also pro- Oligocene Transition in North America. Cambridge vided valuable discourse on the taxa and problems of University Press, United Kingdom. the Arikareean. My thanks are owed to those who col- Butler, R. F. 1992. Paleomagnetism: magnetic domains lected and prepared the Wagner Quarry fossils over 30 to geologic terranes. Blackwell Publishers, Boston, years including: Richard Tedford, Ted Galusha, Loren Massachusetts,.319 p. Toohey, Robert Hunt, Jr., Robert Skolnick, Xiao-feng CoBabe, E. A. 1996. Leptaucheniinae. Pp. 574-580 in Chen, Jim Swinehart, Carl Swisher, and Ellen Stepleton. D. R. Prothero~ & R. J. Emry, eds.The terrestrial For help in collecting paleomagnetic samples my thanks Eocene-Oligocene Transition in North America. Cam- go to Efthimia Papastavros and Abaco Richardson. bridge University Press, United Kingdom. Bruce Bailey deserves special appreciation for many Darton, N. H. 1899. Preliminary report on the geology hours ofproductive discussion and providing unlimited and water resources of Nebraska west of the one access to the specimens of the Ridgeview lf (collected hundred and third meridian. United States Geological through funding by the Nebraska Department of Roads). Survey, 19th Annual Report 1897-1898, 4:719-785. Josep Par6s and the staffofthe University of Michigan Dawson, M. R. 1938. Later Tertiary Leporidae ofNorth geomagnetic laboratory deserve great recognition and America. Univ6rsity ofKansas Palaeontological Con- tributions, Vertebrata, Article 6:1-75.thanks for allowing the use of their facilities and for giv- Effinger, J. A., 1998. Entelodontidae. Pp. 375-380 in C. ing valuable education on the, processes of M. Janis, K. M: Scott, & L. L. Jacobs, eds. Evolution paleomagnetics. My appreciation also goes to two anony- of Tertiary Mammals of North America, Volume 1, mous reviewers who greatly improved this manuscript Terrestrial Carhivores, Ungulates, and Ungulatelike for publication. Continued access to Wagn6r Quarry was Mammals. Cambridge University Press, United King- generously granted by Walter Montague, Chadron; Ne- dom. • braska. Fisher, R. A. 1953. Dispersion on a sphere. Royal Soci- ety of London.Proceedings, 217: 295-305. REFERENCES Frailey, D. 1979. The large mammals of the Buda Local Albright, L. B., III. 1999. Ungulates ofthe Toledo Bend Fauna (Arikareean: Alachua County, Florida). Bul- Local Fauna (Late Arikareean, Early Miocene), Texas letin ofthe F16rida State Museum, Biological Science, Coastal Plain. Bulletin ofthe Florida Museum ofNatu- 24(2):123-173. ral History, 42:1-80. Galbreath, E. C., 1953. A contribution to the Tertiary Bailey, B. E. 1992. 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