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FEB29 44 LIBRARIES 7

(Received 21 February 1983) Abstract

Tanyops undans Marsh, 1894, a tapirid from upper Oligocene strata of South Dakota, has been almost totally ignored in the literature. Here the unique holotype specimen is redescribed and illustrated for the first time. 7Janyops undans |s virtually identical in morphology to, and thus a junior subjective synonym of, Protapirus obliquidens Wortman and Earle, 1893.

Key Words

Tanyops, Protapirus, Tapiroidea, Oligocene, fossil mammal.

Introduction

In 1893 Wortman and Earle described the first known North American representatives of the earliest tapirid genus, Protapirus Filhol, 1877; Protapirus simplex from the middle Oligocene of South Dakota and Pro- tapirus obliquidens from the upper Oligo-

ral History, Yale University. All rights reserved. No part of this publication, except brief quotations for scholarly purposes, may be reproduced without the written permission of the Director, Peabody Museum of Natural History.

29 July 1983

Tanyops undans Marsh, 1894: A Junior Subjective Synonym of Protapirus obliquidens Wortman and Earle, 1893 (Mammalia, Perissodactyla)

Robert Milton Schoch

cene of South Dakota. The following year Marsh (1894), without mentioning Wort- man and Earle’s recent work, described a new genus and species of tapiroids, Tanyops undans, in a 145-word, unrefer- enced and unillustrated paper. This taxon was based on “a pair of lower jaws in good condition recently found in the M/ohippus beds of South Dakota.” (This specimen probably comes from upper Oligocene strata; see below.) Hatcher (1896) subse- quently reviewed early tapirid evolution in North America and described the new spe- cies Protapirus validus from the late Oligo- cene of South Dakota, but failed to mention Tanyops. |n his review and discussion of Hatcher's paper, Earle (1896) also failed to mention 7anyops, as did Sinclair (1901) in describing the new species Protapirus robustus from the upper John Day Forma- tion (upper Oligocene-lower Miocene) of Oregon. Scott (1941) also failed to mention Tanyops undans in his monograph on the perissodactyls of the White River Oligocene. Indeed, to my knowledge, since its description, 7anyops has only been mentioned twice in the literature. Schlaikjer (1937) based his brief discussion of Tanyops solely on Marsh's (1894) descrip- tion without seeing the actual specimen, and tentatively retained it as a valid taxon. Simpson (1945, p. 140) stated without explanation that Protapirus included Tanyops. Here | illustrate, describe and dis- cuss the holotype and only known speci- men of 7anyops undans, Yale Peabody Museum (YPM) 12026, and conclude that

2 Tanyops undans. aSynonym of Protapirus obliquidens

Postilla 190

this taxon is based on a specimen referable to Protapirus obliquidens. From hand- written notes found with YPM 12026 it is evident that Leonard Radinsky came to es- sentially the same conclusion, although he failed to mention it in print (see Radinsky, 1969, and his earlier works on perisso- dactyls cited therein). Tooth nomenclature follows Radinsky (1969, fig. 1).

Systematic Paleontology CLASS Mammalia Linnaeus, 1758

ORDER Perissodactyla Owen, 1848 SUBORDER Ceratomorpha Wood, 1937

SUPERFAMILY Tapiroidea Burnett, 1830 (Gill,

1872) FAMILY Tapiridae Burnett, 1830 Protapirus Filhol, 1877

New Synonym

Tanyops Marsh, 1894 (type species= Tanyops undans Marsh, 1894).

Protapirus obliquidens \Wortman and Earle, 1893 (Fig. 1, Table 1)

New Synonym

Tanyops undans Marsh, 1894.

Referred Specimen

YPM 12026, mandible with roots of right |,_3, right and left C,, P,-M,, left M, and al- veolus for right M., isolated crowns of right |,_, and right |, partially imbedded in matrix against its lingual face (holotype of Tanyops undans Marsh, 1894).

Fig. 1.

Holotype of 7anyops undans Marsh, 1894, YPM 12026. A, occlusal view of left C,, P>-M3: B, labial view of left C,, P2-M,; C labial view of right lz; D labial view of right |p; & lingual view of right I,; F labial view of right 1,; G lingual view of right |,; 4, lateral view of left dentary. Note separate scales for Aand 8, C-G and for H. Drawing by Ruth Santer.

SI Tanyops undans: aSynonym of Protapirus obliquidens

Postilla 190

Horizon and Locality

Collected by Henry F. Wells in the summer of 1894 from “the Miohippus beds of South Dakota” according to Marsh (1894), but from the “Protoceras beds” according to Wells (letter dated 11 Aug. 1894 from Wells to Marsh, Othniel Charles Marsh Papers, Manuscripts and Archives, Yale University Library). Thus this specimen probably comes from upper Oligocene strata (Wood et al., 1941).

Description YPM 12026 is a well-preserved, nearly com-

plete mandible (Fig. 1) that is virtually identical to a lower jaw of Protapirus obli-

quidens in the American Museum of Natu- ral History, New York, described and il- lustrated by Wortman and Earle (1893, pp. 165-67, figs. 2, 3) and Scott (1941, p. 760). YPM 12026 differs from the American Museum specimen primarily in having a somewhat shorter mandible and diastema length (Table 1).

A summary of important morphological features of YPM 12026 follows. 1) The spa- tulate incisors decrease in size posteriorly. 2) The lower canine is placed directly poste- rior to |, and is relatively small. 3) There is a moderate diastema between C, and P., and P, is absent. 4) The remaining premolars are all double-rooted, increase in size posteriorly, and are submolariform. P,_, bear distinct trigonids and talonids; however, the talonids are relatively short

Table 1

Comparative measurements (in mm) of Tanyops undans (YPM 12026) and Protapirus ob- liquidens (from Wortman and Earle, 1893, p. 167, fig. 2). Measurements of P. ob/iquidens

are a composite of both right and left sides.

Tanyops undans

Right Side Length Width

P. obliquiders

Left Side Length Width

Length Width

I, 6.4 8.0 I, Sone Tell I, _ 48 C, 6.8 63 70 6.2 P, Shs) OW 143 10.6 16.0 TARO P. 14.5 (Zee) 143 (28) 152 123 Pa 14.4 14.3 15:0 14.0 16.4 14.5 M, 16.4 isn 173 12.8 M, 192 13.4 19.2 14.0 20.8 14.2 3 — _ 2016. 14:5 24.6 148 P,_, length 44.6 42.4 47.41 M,_3 length aa 58.2 60-1 P,-M, length — 103.5 1087+ 1 C,-P, Diastema 30.0 28.0 S78), 25 || Depth of ramus below M, 43.1 42.8 40. + 1 Totallengthofjaw 235+ 2605 +71

4 Tanyops undans. aSynonym of Protapirus obliquidens

(anteroposteriorly), low and wide and bear distinct and separate entoconids and hypoconids. In none of the premolars are the entoconids and hypoconids connected to form high, transverse hypolophids as in the molars. 5) The molars bear trigonids and talonids that are subequal in length and width. The protolophids and hypolo- phids are tall, transverse crests (the protolo- phids are slightly higher than the hypolophids). The paralophids and meta- lophids are extremely reduced on M,_.. 6) There is only the slightest trace of a hypoco- nulid lobe on M..

Discussion

In his original description Marsh (1894) dis- tinguished 7anyops as a form with “essentially the same dentition as 7apirus, but the last premolar only is like the molars.” Schlaikjer (1937, p. 248) interpret- ed Marsh's description as indicating that Tanyops had a relatively molariform P, with a complete and high hypolophid (“posterior cross crest” of Schlaikjer). Otherwise, Schlaikjer could not distinguish Tanyops undans from Protapirus obliquidens. \n Protapirus P._, are all sub- molariform and lack complete, high, well- developed hypolophids (Wortman and Earle, 1893), whereas in the Miocene genus Miotapirus and in later tapirs such as 7api- ravus and Japirus the hypolophids are complete, high and well developed on P3 4 or P.._, (Hatcher, 1896; Schlaikjer, 1937; Olsen, 1960). Thus on the basis of Marsh's (1894) description, Schlaikjer (1937) provi- sionally retained 7anyops undans as a valid genus and species morphologically in- termediate between Protapirus ob/iqui- dens and Miotapirus harrisonensis. However, Schlaikjer (1937, p. 248) also stated that “it may prove to be a more ad- vanced species of Protapirus.”

As is evident from the description and illustrations (Fig. 1) of YPM 12026 that | have presented above, Marsh’s (1894) origi- nal description of the holotype of 7anyops undans is misleading. In YPM 12026 the P,

Postilla 190

bears a distinct and separate hypoconid and entoconid. These conids are as in the referred specimens of P. ob/iquidens (Wortman and Earle, 1893; Scott, 1941: the holotype of P. ob/iquidens includes only an upper dentition) and are not connected by a well-developed hypolophid as In Miotapirus. P,_, are all submolariform in Tanyops undans as in Protapirus.

If Tanyops undans is compared to Pro- tapirus obliquidens, YPM 12026 is only very slightly smaller than the lower jaw originally referred to P. ob/iquidens by Wortman and Earle (1893, fig. 2). This is pri- marily seen in the somewhat shorter mandi- ble and diastema of 7anyops undans (Table 1); however, the cheek teeth of the two specimens are of nearly the same size (Table 1). Differences seen in the sizes of the cheek teeth in the two specimens are of the same order of magnitude as differences seen in some cases between the right and left teeth of YPM 12026 (Table 1). | believe that this indicates that YPM 12026 repre- sents a slightly smaller individual (perhaps a female?) than the American Museum specimen (perhaps a male?), not that they necessarily represent different taxa. Furthermore, Protapirus may be closely related to Colodon occidentalis, an early to middle Oligocene helaletid tapiroid known from a moderately large number of specimens (Radinsky, 1963). Co/odon occi- dentalis is slightly smaller than Protapirus obliquidens and Tanyops undans; yet in- dividuals referable to this species show as great a range in cheek tooth size as is seen between 7anyops undans and Protapirus obliquidens. (Compare Table 1 with Radinsky’s, 1963, p. 64, table 10, “Statistical data on teeth of Co/odon occidentalis. “) Thus, except for individual variation, YPM 12026 is identical both in size and morphology to specimens of Pro- tapirus obliquidens and therefore is refera- ble to Wortman and Earle’s earlier named taxon. On this basis | consider 7anyops undans Marsh, 1894, to be a junior subjec- tive synonym of Protapirus obliquidens Wortman and Earle, 1893.

5 Tanyops undans: aSynonym of Postilla 190 Protapirus obliquidens

Historical Context Acknowledgments

The sequence of events relating to the dis- covery and description of 7anyops undans — | thank John H. Ostrom for allowing me to is as follows. YPM 12026 was collected by study specimens in his care, and L. B. H. F. Wells in the summer of 1894 (letter Radinsky, B. Tiffney and W. Wall for helpful dated 11 Aug. 1894 from Wells to Marsh, criticism of the manuscript. Othniel Charles Marsh Papers), it was shipped by freight from Hermosa, South Dakota and received at Yale on 7 Septem- ber 1894 as part of Accession Number 2248. The box was unpacked on 20 September (Accession records for Number 2248, Archives of the Division of Vertebrate Paleontology, Peabody Museum of Natural History), Marsh wrote his description of Tanyops, submitted it to the American Journal of Science on 22 September (Marsh, 1894) and it was published in October, 1894. Originally the collector, H. F. Wells, asked Marsh for $10.00 for YPM 12026 (letter dated 11 Oct. 1894 from Wells to Marsh, Othniel Charles Marsh Papers). After much haggling, Marsh paid Wells $500.00 for approximately three dozen specimens from South Dakota including the “tapir jaws.” This Sum was not paid in full until 18 May 1895 (letter dated 18 May 1895 from Wells to Marsh, Othniel Charles Marsh Papers), long after Marsh had initially described 7anyops.

In 1893 several papers on early tapirids were published (Earle, 1893a, 1893b; Wort- man and Earle, 1893). All of these found their way into the Peabody Museum Library; however, | cannot positively state that Marsh saw any of them before his pub- lication of Tanyops. Yet Marsh was not unfamiliar with tapirs (e.g., Marsh, 1877, 1890) and he owned a copy of Filhol (1877) in which Protapirus is described. Still, Marsh published only a hastily written de- scription of 7anyops, failing to compare it to any genera other than Co/odon and Tapirus, and never referred to 7anyops again in his later papers.

6 Tanyops undans. aSynonym of Postilla 190 Protapirus obliquidens

a

Literature Cited

Burnett, G. T. 1830. Illustrations of the Quadrupeda, or quadrupeds, being the arrangement of the true four-footed beasts, indicated in outline. Quart. J. Sci. Lit. Art 26:336-53.

Earle, C. 1893a. Some points in the comparative osteology of the tapir. Science 21:118.

1893b. The evolution of the American tapir. Geol. Mag. 10:391-96.

-1896. Tapirs past and present. Science 4:934-35.

Filhol, H. 1877. Recherches sur les Phosphorites du Quercy. Bibliotheque de |’Ecole des Hautes Etudes, Paris 16:1-338.

Gill, T. 1872. Arrangement of the families of mammals with analytical tables. Smithsonian Misc. Coll. 11:1-98.

Hatcher, J. B. 1896. Recent and fossil tapirs. Am. J. Sci., Ser. lV, 1:161-80.

Linnaeus, C. 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Editio decima, reformata. Stockholm, Laurentii Salvii, 824 pp.

Marsh, O.C. 1877. Introduction and succession of vertebrate life in America. Am. J. Sci., Ser. Ill, 14:337-78.

1890. Notice of new Tertiary mammals. Am. J. Sci., Ser. Ill, 39:523-25.

1894. A new Miocene tapir. Am. J. Sci., Ser. Ill, 48:348.

Olsen, S.J. 1960. Age and faunal relationship of 7ap/ravus remains from Florida. J. Paleontol. 34:164-67.

Owen, R. 1848. Description of teeth and portions of jaws of two extinct anthracotherioid qua- drupeds (Hyopotamus vectianus and Hyop. bovinus) discovered by the Marchioness of Hastings in the Eocene deposits on the N. W. coast of the Isle of Wight: with an attempt to develop Cuvier’s idea of the classification of pachyderms by the number of their toes. Quart. J. Geol. Soc. London 4:103-41.

Radinsky, L. 1963. Origin and early evolution of North American Tapiroidea. Bull. Peabody Mus. Nat. Hist. (Yale Univ.) 17:1-115.

1969. The early evolution of the Perissodactyla. Evolution 23:308-28.

Schlaikjer, E.M. 1937. A new tapir from the lower Miocene of Wyoming. Harvard Univ., Bull. Mus. Comp. Zool. 80:231-51.

Scott, W.B. 1941. Perissodactyla. The mammalian fauna of the White River Oligocene. Trans. Am. Philos. Soc. 28:747-974.

Simpson, G.G. 1945. The principles of classification and a classification of mammals. Bull. Am. Mus. Nat. Hist. 85:1-350.

Sinclair, W.J. 1901. The discovery of a new fossil tapir in Oregon. J. Geol. 9:702-07.

Wood, H.E. 2nd. 1937. Perissodacty! suborders. J. Mammal. 18:106.

Wood, H.E. 2nd, R.W. Chaney, J. Clark, E.H. Colbert, G.L. Jepsen, J.B. Reeside and C. Stock. 1941. Nomenclature and correlation of the North American continental Tertiary. Geol. Soc. Am. Bull. 52:1-48.

Wortman, J.L. and C. Earle. 1893. Ancestors of the tapir from the lower Miocene of Dakota. Bull. Am. Mus. Nat. Hist. 5:159-80.

7 Tanyops undans: aSynonym of Postilla 190 Protapirus obliquidens

The Author

Robert Milton Schoch, Department of Geology and Geophysics and Peabody Museum of Natural History, Yale University, 170 Whitney Avenue, P.O. Box 6666, New Haven, CT 06511.

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