The Downtonian and Devonian vertebrates of Spitsbergen. XV*. New Heterostracans from the Lower Devonian Red Bay Group, northern Spitsbergen ROBERT R. ILYES, YOSHIHIDE OHTA and JONNY GUDDINGSMO Ilyes, R. R . , Ohta. Y. & Guddingsrno, J . 1995: The Downtonian and Devonian vertebrates of Spitsbergen. XV* New Heterostracans from the Lower Devonian Red Bay Group, northern Spitsbergen. Polar Research Id(]), 33-42. A new vertebrate fauna consisting of two new species of heterostracans (jawless vertebrates), Aiig1aspi.r glelsoiki (Cyathaspididae) and Proiopreraspis rnicra (Pteraspididae), is described from the Wulffberget Member of the Red Bay Conglomerate Formation, northern Spitsbergen. This is the oldest known vertebrate fauna of typical Early Devonian age on Spitsbergen. The discovery of this vertebrate fauna improves the distribution and diversity of early vertebrates in the Red Bay Group. Robert R. Ilyes arid Yoshihide Ohta. Norsk Polminstituit, P . 0. Box. 5072, Majorstua, N-0301 Oslo. Norway; Jonny Guddingsmo. Geology Diuision. Instituff for Biology and Geology, University of Trornsm. N-9037 Tromsq?, Norway. Introduction is located at the base of the Fraenkelryggen For- The Lower Devonian Red Bay Group is the lowermost vertebrate-bearing unit of the Devonian “Old Red Sandstone” deposits of Spits- bergen. The Red Bay Group overlies the older Siktefjellet Group with an angular unconformity and is divided into four formations: the Red Bay Conglomerate Formation, the Andreebreen For- mation, the Fraenkelryggen Formation, and the Ben Nevis Formation (Fig. 1). The Red Bay Conglomerate Formation is further separated into three members, (from bottom to top) the Wulffberget Member, the Rabotdalen Member, and the Princesse Alicefjellet Member. Thirty vertebrate-bearing horizons have pre- viously been recognised in the Red Bay Group (Blieck & Heintz 1979), with the oldest being the “ P s a m m o ~ t e ~ s ” horizon. In the original inter- pretation by Kiaer & Heintz (1939, this horizon mation. However, based on a re-examination of the data, Gjelsvik & Ilyes (1991) suggested that the “Psammosteus” horizon is actually located in the yellow-green sandstones of the upper part of the Andreebreen Formation. Gjelsvik & Ilyes did not investigate the actual locality but re-inter- preted the original field observations in relation to Gee’s 1966 map. The oldest vertebrates from the “Old Red” deposits of Spitsbergen prior to this study were reported by Gjelsvik & Ilyes (1991). who regarded most of their vertebrate localities to belong to the Andreebreen Formation. Some scattered fragments of primitive spore plants and ostracods have been found in the Rabotdalen Member (MuraSov & Mokin 1979), but no verte- brates have been reported from below the AndrCebreen Formation until now. The new occurrence of heterostracans. both cvathasuidids and pteraspidids, in the Wulffberget Member of the Red Bay Conglomerate is therefore signifi- cant. The description of two new heterostracans * Correctmi There has been an error in the numbering of the previous paper in the series “The Downlonian and Devonian vertebrates of Spitsbergen”. Blieck A B N. Heintz’s “The Cyathaspids of the Red Bay Group (Lower Devonian) of Spits- bereen” (Polar Reg. 1 n . s . . 1983. DD. 49-73) should have been increases their diversity and stratigraphical dis- tribution in the Red Bay Group’ found One o f t h e authors (y. 0.) . , ~ .. XIV of the series and not XIII. N. Heintz’s “The theolodont vertebrates in a limestone conelomerate assigned Y ” Sigurdia lafa n.g., n.sp. from the Lower Devonian at Sigurdfjel- let, Spitsbergen” (Norsk Polarinsi. Arbok 1970, pp. 112-116) was number XIII. The current paper is therefore number XV in the series ( a complete list of the previous publications in the to Red Bay Conglomerate Formation in the west- however, been carried O u t On the ern end of Richardvatnet, Spitsbergen. No further studies series is found on pages 41-42). material. 34 R. R . Ilyes et a l . 3 8 c Formation Member Lithology Ben Nevis 900 m Erer, . micaccous sandstone Frznkelryggen MX) m grcy-green. yellowgrey %and/siltstone. basal grit Andreebreen >100 m ~~ alternating red and green sand/siltstone Red Ba) Conglomerate Cnconformit! Siktefjellet Sandstone 350 m Lilljeborgfjellet Conelomerate 4 K J m Princesse Alirefjellet 300 m Rabotdalen 20(1 m sandstone WulfIbergct coarse. massive marble conglomerate 200 m matrix supported. quartz chip conglomerate grey-green. in lower part multicoloured --- grey-green sand/siltstone massive. polyniict conglomerate F i g . 1. Stratigraphy and lithology of the Red Bay Group and the Siktefjellet Group in northern Spitsbergen (from Gjelsvik & Ilyes 1991 1 I - I I . - I Material and methods The fossil material described here comes from one locality on Hesteskoholmen, a small island located in the northwestern part of Liefdefjorden (Figs. 2 and 3 ) . The material has been collected in situ in the stratigraphic section. The cyathaspidids represent the majority of the vertebrates found at this locality. The specimens are preserved in a tough micaceous sandstone that can be prepared mech- anically. The measurements employed follow those used by Blieck & Heintz (1983) for cya- thaspidids (Table 1). and Blieck (1984) for ptera- spidids (Table 2). The specimens are deposited in the collections of the Paleontologisk Museum, Oslo, and bear their catalog numbers (prefixed PMO). Fig 2. Map showing the new Early Devonian vertebrate locality on Hesteskoholmen. northern Spitsbergen. Boxed area depicts arrashown on Fig 3 . Symbol,: 1. glacier andmoraine. 2. Wood Bay Fm.. 3 . Ben N e w Fm. (Rcd Bay GI.): 4, Frznkelryggen Fm. (Red Bay G r . ) ; 5 . Andreebreen Fm. (Red Bay Gr.): 6. Wulffhergct Mbr. (Rcd Bay Gr ): 7 . Siktefjellet Sandstone: 8. Lill]ehorgfjellet Conglomerate: 9. phyllite and marble. 10. boundaries. 11. steep faults; 12. fault with dip: 13. thrusts: 14. covered b\ scree. Geological setting The new vertebrate-bearing unit is located in t h e Wulffberget Member of the Red Bay Con glomerate. It is a red sandstone bed interbedded in a less stratified, coarse, and massive marble- dominated conglomerate (Fig. 4). The con- glomerate is of typical Wulffberget Member type, which forms the whole of the western part of the The Downtonian and Devonian vertebrates of Spitsbergen 3.5 ~ Fig. 3. Local geology of Hesteskoholmen and surrounding areas. Arrow points to the new vertebrate locality island Hesteskoholmen. The vertebrate-bearing bed is one of two sandstone beds interbedded in the conglomerate in this area, and the only one known to have vertebrates. The vertebrate-bearing sandstone is approxi- mately 1.5 m thick and at least 8 m in length. To Fig. 4. The geology of the new vertebrate locality in the Wulffberget Member of the Red Bay Conglomerate Formation. Captions: sst, sandstone; cgl, conglomerate. the east the vertebrate-bearing unit is bounded by a local fault, and to the west an approximately 2 m thick conglomerate very rich in marble blocks occurs without a structural break. Based on the field observations it is suggested that the vertebrate-bearing sandstone bed is a sandstone lens interbedded in the conglomerates of the Wulffberget Member. Systematic paleontology Order Heterostraci Lankester, 1868 Family Cyathaspididae Kim, 1932 (Cyathaspi- dae) Genus Anglaspis Jaekel, 1927 Definition. - See Denison, 1964: 428. Type species. - Cyathaspis macculloughi Wood- ward, 1891. Other species. - A . macculloughi (Woodward, 1891) type species, A . insignis Wills (1936), A . heintzi Blieck & Heintz (1983), A . elongata Blieck & Heintz (1983), A . expatriata Denison (1964). Anglaspis gjelsviki n. s p . Figs. 5 , 6 and 7. 36 R . R . llyes ei al. Etymology. - Named after T o r e Gjelsvik for his work on the Lower Devonian stratigraphy of Spitsbergen. H o l o y p e . - Dorsal shield P M O 141.565. Paravpes. - Dorsal shields P M O 141.566- 141.575; ventral shields P M O 141.576, P M O 141.577; branchial plate P M O 141.578; scales P M O 141.579-141.582. All from the same locality in the Wulffherget Member of the Red Bay Con- glomerate Formation. Locus typicirs and sfraruni rypicuni. - Hes- teskoholmen; Wulffberget Member of the R e d Bay Conglomerate Formation. Diagnosis. - A species of Anglaspis with finer ornamentation ( 5 4 dentine ridges per mm) than all o t h e r species of this genus. and distinctive morphology of the dorsal shield. Mrasirrenzerzts. - Table 1. Description. - T h e dorsal shield is narrow and gently d o m e d , with a prominent pineal macula. T h e lateral epitega form brims; shield constricted at the branchial openings. Branchial plate long with a sharp lateral angulation. Ornamentation of fine dentine ridges. 5-6/mm; sharply crested anteriorly and laterally. round crested on remain- der of shield. Lateral-line sensory canal system Fig. 5 . Anglmprsgjelrurki n . sp. Dorsal view of holotype (dorsal shield). P M O 111 5 6 5 . 4 . 5 X . Fig. 6. A r ~ g l ~ p i r g j e l s v i k i n . sp. PMO 141.574 SEM micrograph showing detail of ornamentation on mid part of dorsal shield, 15 x . The Downtonian and Devonian vertebrates of Spitsbergen 37 Tuble 1. Measurements (in mm) for Anglaspis gjelsuiki n . sp. All measurements taken on dorsal shield except for length and width of ventral shield Orbital width: 7-10 ( n = 9) Orbital length: >5 (n = 9) Total width: 10-13 ( n = 9) Total length: 18-22 ( n = 9) Pineal length: 4-5 (n = 9) Postbranchial length: 3-6 (n = 9) Width ventral shield: 10-12 (n = 3) Length ventral shield: 18-20 (n = 3) Dentine ridges/mm: 5-6 ( n = 9 +) unknown (the preservation of the shields makes it impossible to trace the lateral-line canal system). Ventral shield is gently arched, almost flat, anteriorly and strongly arched posteriorly. Discussion. - This species is very similar to Ang- laspis insignis in size. The two forms differ, how- ever, in the overall morphology of the dorsal shield. Anglaspis gjelsuiki is narrower and the postbranchial length of the dorsal shield is greater than in A . insignis. This makes the posterior part of the dorsal shield more pointed in A . gjelsviki n sp. than in A . insignis. There is also a noticeable difference in the coarseness of the dentine ridges on the central part of the dorsal shield between the two forms, which is a very important taxo- Fig. 7. Ang/arpis gjelsoiki n. sp. Drawing of dorsal view of dorsal shield PMO 141.565, holotype. Scale bar = 5 m m ; Abbreviations: orb, orbit; bro, branchial opening. nomic difference. Anglaspis insignis have the coarser ornamentation of the two, with 3-4 ridges per mm compared t o 5 4 per mm in this species. Denison (1964) noted, however, that the coarse- ness of the dentine ridges varies between 3.5 and 5 ridges per mm centrally in A. insignis. A study of the type material and other material of A . insignis in the collections of the Paleontologisk Museum, Oslo, concludes that the coarseness varies only between 3 and 4 ridges per mm, just as stated by Blieck & Heintz (1983). The new form shows a very small individual variation in the coarseness of the dentine ridges, as do the other species of the genus Anglaspis. The study of the type material suggests that the new form is a valid species, which can be sep- arated from A . insignis by its noticeably finer ornamentation and distinctive morphology of the dorsal shield. Family Pteraspididae Claypole, 1885 Subfamily Pteraspidinae Claypole, 1885 Genus Protopteraspis Leriche, 1924 Dejinition. - See Elliot & Dineley, 1983; 478. T y p e species. - Protopteraspis gosseleti Leriche, 1924. Other species. - P . aquilonia Blieck (1981). P?. arctica Elliot & Dineley (1983), P?. corniga Elliott & Dineley (1983), P. leathensis (White, 1935), P. primaeva K i m (1928). P. pygmaea Elliott & Dineley (1983), P. sartokia Elliot & Dinely (1983), P. silikrokia Elliott & Dineley (1983), P . vogti K i m (1928), P . whitei (Denison, 1955). Protopteraspis micra n. sp Figs. 8 and 9. Etymology. - Greek: pi’~p6[, &, b i f . small, refer- ring to the very small size of members of this species. Holotype. - Dorsal shield PMO 141.58S141.584 (part and counterpart). Paratype. - Dorsal shield PMO 141.585. From the same locality as the holotype. L o c u s typicus and stratum typicum. - Hes- teskoholmen; Wulffberget Member of the Red Bay Conglomerate Formation. 38 R . R. Ilyes et al. Fig. 9. Reconstruction of Protopterusprr micra n . sp. Dorsal view of dorsal shield. Scale bar = 7 mm; Abbreviations: orb, orbital plate: bro. branchial opening; brpl, branchial plate: cpl, cornual plate: ioc. inter-orbital canal; mdc. median dorsal canal. Fig. 8. Protopteruspis micro n. sp. Dorsal view of holotype (dorsal shield). PMO 141.583. 2.7x. Diagnosis. - Small protopteraspid with short, broad, and moderately arched dorsal shield and bluntly rounded rostral plate. Orbital plate small, and widely separated from small pineal plate. Branchial plate long and curved, expanding pos- teriorly t o branchial opening. Branchial duct opening dorsally well in advance of postero- lateral corner of dorsal shield. Cornual plate small and subtriangular with blunt postero-lateral point, Ornamentation of fine. sharply crested, dentine ridges with crenulated lateral margins, 8- 9/mm. Measuremerits. - See Table 2 . Descripori. - T h e dorsal disc is oval and gently domed. Rostra1 plate broad, short. and bluntly rounded: subrostral area not preserved. Orbital plate small: posterior extension unknown. Orbital plates extend only a short distance medially towards the pineal plate. Pineal plate small and subrounded. Branchial plate long, and forming much of t h e lateral margin of the dorsal shield; it is narrow anteriorly, but expands slightly pos- teriorly and reaches its maximum width at t h e posteriorly situated branchial opening. T h e bran- chial duct opens dorsally well in advance of the postero-lateral corner of the dorsal shield. Cor- Tab(e2. Measurements (in m) for Proropteruspis micra n. sp. ( ) indicates estimated values. All measurements taken on dorsal shield. n = measured specimens. Length dorsal shield: 25-28 ( n = 2) Width dorsal shield: l t e 2 l ( n = 2) Length dorsal disc: 1%23 ( n = 2) Width dorsal disc: l S ( 1 8 ) ( n = 2) Lcngth rostral plate: M (n = 2) Width rostral plate: %12 ( n = 2) Length hranchial plate: 12 ( n = I ) Length cornual plate: 5 (n = 1) Width cornual plate: 2 ( n = 1) Length pineal plate: 1.02 ( n = 1) Width pineal plate: 1 (n = 1) Length orbital plate: ? Length dorsal spine: ? Height dorsal spine: ? Dentine ridges/mm: b 9 ( n = 2) The Downtonian and Devonian vertebrates of Spitsbergen 39 nual plate small and subtriangular, with blunt postero-lateral point. Dorsal spine poorly pre- served, but appears to be stout, and laterally compressed. The lateral-line sensory canal system is incom- pletely known. The medial dorsal canals diverge and terminate before reaching the inter-orbital canal. The inter-orbital canal forms a “V” shaped loop on the dorsal disc. Ornamentation of fine, sharply crested, dentine ridges with crenulated lateral margins, &9/mm. We have decided not to make SEM micrographs of the ornamentation as it would mean the destruction of one of the two existing specimens of this species. No specimen of the ventral shield of this species is known. Discussion. - The important taxonomic charac- ters preserved on the dorsal shield indicate that this new form is undoubtedly a representative of the genus Protopteraspis. The morphology of the pineal-orbital area and the lateral-line sensory canal system show typical protopteraspid pattern. The pineal plate is widely separated from the orbital plates, and the medial dorsal canals di- verge and do not connect with the inter-orbital canal. The inter-orbital canal forms the “V” shaped loop on the dorsal disc typical for the protopteraspids (Elliott & Dineley 1983). The previously described protopteraspids from Spitsbergen are shown in Fig. 10. The size and morphology of Protopteraspis micra clearly sep- arate it from P . v o g i and P. aquilonia. The overall morphology of the new species is quite similar to Blieck’s (1981) reconstruction of P. primaeva. A comparison of the new species with the type material of P. prcmaeva shows that the two forms differ in size, P . micra being noticeably smaller. There is also a morphological difference between these two species found in the shape of the con- nection between the rostra1 plate and the dorsal disc, and in the shape of the branchial plate and branchial opening. Other important morpho- logical differences can be found in the shape of the posterior part of the dorsal disc and cornual plate. The noticeable and important morpho- Fig. 10. Previously described protopteraspids from Spitsbergen. All from the Red Bay Group. Scale bar = 10 mm (from Blieck 1984). A = Protopteraspis primaeva, B = P . aquilonia, C = P . vogti. V 40 R . R. Ilyes et al. logical differences between the two forms indicate for US that p . micro is a species different from P . primaeua. Intraspecific variability is known in the pteraspidids, e.g. Profopteraspis gosseleti and Pteruspis rostrura ( A . Blieck pers. commun.), but we feel that the difference in morphology between Protoprerapk micra and p . primaeva is too great to indicate intraspecific variability. We feel. how- ever, that the two species are closely related. plete specimens of variable size, indicating that there has been little or no size sorting of the fossils. The fossil material has no preferred Onen- tation. The data suggest that the origin of the fossil material was in or close to the area of deposition, and that the disarticulation of the material was in situ by current action and biogenic activity. Age and significance of the Invertebrates and palaeoecology vertebrate fauna In addition to the vertebrates, the rock samples Early Devonian vertebrate faunas of similar over- contain bivalves (Fig. 11). Their preservation is all composition to that found in the Wulffberget extremely poor, and the bivalves appear Only Member of the Red Bay Conglomerate have pre- as molds and casts in the matrix. The largest viously been described from the Frznkelryggen specimens have a length around 15 mm and width and Ben Nevis Formations (Blieck et al. 1987). around 11 mm. NO important taxonomic features The Wulffberget Member fauna has, however, no are preserved, making their determination dif- species in common with the other known verte- ficult. The external morphology of the bivalves brate faunas of the Red Bay Group, and their suggests that all t h e individuals belong to Modi- similarity is only at the generic level. omorpha? sp. This genus is COmmOn in Upper An accurate dating of the Wulffberget Member Silurian, Lower and Middle Devonian sand- and has been difficult to obtain because the strata siltstones (C. Babin pers. comm.). contain no characteristic microfossils useful in This species appears to be a restricted shelly dating. The occurrence of Protoptermpis and invertebrate fauna present in the vertebrate-bear- AngLnspis, two typical Early Devonian genera in ing strata. No brackish water indicators or normal Spitsbergen, suggests an Early Devonian age for marine indicators have been found in the studied these strata. An Early Devonian age (Loch- samples. However, due to a lack of an accurate kovian) for the lower parts of the Red Bay Group sedimentologic log it is not possible to determine was also suggested by MuraSov & Mokin (1979) the depositional environment at the present time. and Blieck et al. (1987). MuraSov & Mokin All the studied bivalves are disarticulated, and reported (but did not figure) the Occurrence of only one of the cyathaspidid specimens has articu- typical Early Devonian plant fragments from the lated dorsal and ventral shields (PMO 141.575). Rabotdalen Member of the Red Bay Con- The studied fossil material shows, however, no glomerate. This substantiates the Early Devonian Signs Of abrasion. The composition of the fossil age on the base of this formation suggested by material ranges from minute fragments to com- the new vertebrates. MuraSov & Mokin (1979) also reported Early Devonian plants from the base of the type strata of the Siktefjellet Group on the northern side of Liefdefjorden. The new data indicate that the Silurian/Devonian boundary on Spitsbergen is located somewhere below the Red Bay Group, maybe in the Siktefjellet Group. New field evi- dence suggests however, that the MuraSov & Mokin plant locality is actually located in the Wulffberget Conglomerate, making their age dating somewhat dubious. The correlation of the Devonian of Spitsbergen to the “classic” Anglo-Welsh area has been, and still is, quite problematic. Blieck et al. (1987) correlated the “Psammosteus” horizon of Spits- bergen with the Anglo-Welsh pococki zone. The Fig ZI. Crnidentified hivalve, PMO 141.586, 4 . 5 X The Downtonian and Devonian vertebrates of Spitsbergen 41 genera Protopteraspis and Anglaspis occur together in the Anglo-Welsh synzondsi zone, but Anglaspis is not registered in the pococki zone (Blieck & Heintz 1979). Based on this information it is tentatively sug- gested that the Wulffberget Member at the base of the Red Bay Conglomerate, and then also the base of the Red Bay Group, might also correlate with the Anglo-Welsh pococki zone. This indi- cates that the stratigraphic section between the base of the Red Bay Conglomerate, where the new fauna comes from, and the “Psammosteus” horizon is fairly close in time, and that the exten- sive lithostratigraphic separation of the two faunas is due to a high sedimentation rate. So far no microvertebrates (thelodonts) or spores have been found in the samples from the Wulffberget Member to support this hypothesis at the present time. Only further collecting can test this hypothesis. Acknowledgement. - We wish to thank N. Heintz, Paleon- tologisk Museum, Oslo, for critical reading of the manuscript and H. A . Nakrem, Paleontologisk Museum, Oslo, for help with the micrographs. We also wish to thank C. Babin, Univ- ersite Claude Bernard-Lyon 1. France, for help with the bivalves, and A . Blieck, Universite des Sciences et Techniques de Lille-Flandre-Artois. France, for conslructive critique. This paper is a contribution t o IGCP Project 328. References Blieck. A. 1981: Le genre Protoptermpa Leriche (Vtrtibres, Heterostraces) du Devonien inferieur Nord-Atlantique. Palaeontographica A 173, 141-159. Blieck. A . 1984: les Htterostracts Ptkraspidiformes; sys- ttmatique-phlyog~nie-biostratigraphie-biog~ographie. Cahiers de Pal6ontologie (section vertebres)> C . N . R . S . edit., Paris. 195 pp. Blieck. A., Goujet, D. & Janvier, P. 1987: The vertebrate stratigraphy of the Lower Devonian (Red Bay Group and Wood Bay Formation) of Spitsbergen. Modern Geol. 11, 197-217. Blieck, A . & Heintz, N . 1979: The heterostracan faunas in the Red Bay Group of Spitsbergen. Bull. S O C . Geol. de France 7e ser. X X I ( 2 ) , 169-181. Blieck. A. & Heintz, N. 1983: The Cyathaspids of the Red Bay Group (Lower Devonian) of Spitsbergen. 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