Adapidae in N. America Gingerich

8/14/2019 Adapidae in N. America Gingerich

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CONTRIBUTIONS FROM THE MUSEUM OF PALEONTOLOGYGerald R. Smith Director

Robert V. Kesling EditorDiane Wurzinger Edi tor fo r this number

The series of contributions from the Museum of Paleontology is a medium for thepublication of papers based chiefly upon the collection in the Museum. When the num-ber of pages issued is sufficient to make a volume a title page and a table of contents w llbe sent to libraries on the mailing list and to individuals upon request. list of theseparate papers may also be obtain ed. Correspondence should be directed to the Museumof Paleontology The University of Michigan Ann Arbor Michigan 48104VOLS. 11-XXIV. Parts of volumes may be obtained if available. Price lists availableupon inquiry.


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SYSTEMATICS, PHYLOGENY, AND EVOLUTION OF EARLY EOCENEADAPIDAE MAMMALIA, PRIMATES) IN NORTH AMERICA

BYPhilip D. Giilgerich and Elwyn L. S imons

Abstract.- Several large new collections of early Eocene Adapidae have been m adein recent years from stratified sediments in the Big Horn Basin of Wyoming. Thesecollections perm it a m uch more d etailed reconstruction of the evolutionary historyof the genus Pelycodus than was previously possible. Restud y of the describedcollections of early Eocene Adapidae indicates the following taxonomic modifica-tions: Pelycodus tutus Cope is made the type of a new genus Copelemur, whichincludes also C. praetutus, C. feretutus nov.), and C. consortutus nov.). Restudyof New Mexico fossils from the Largo and Alrnagre facies indicates that Pelycodusjarrovii and Pelycodus frugivoms are senior synonyms having priority over P.venticolis and P. nunienus, respectively, from the Lost Cabin beds of Wyoming.Four additional North American species of Pelycodus are recognized: P. ralstoni,P. mckennai nov.), P. trigonodus, and P. abditus nov.).A single lineage of Pelycodus is known from Sand C oulee, Graybull, and Lysitebeds, but in Lost Cabin beds two lineages are known that were both almost cer-tainly derived from the Lysite species Pelycodus abditus. Samples of species fromsuccessively higher stratigraphic horizons are progressively larger, until the secondlineage of Pelycodus appears, after which one lineage begins to decrease in sizewhile the other continues t o increase. This is interpreted as a probable result ofcharacter divergence in body size to minimize comp etition between the tw o sympa-tric species. The mesostyle and hypoco ne b ecome progressively larger through timein Pelycodus. The evolution of Pelycodus appears to be continuous and gradualfrom the earliest to the latest species.

Pelycodus jarrovii is perfectly intermediate between earlier Pelycodus and laterNotharctus, showing that the generic transition from one to the other was alsobo th contin uous and gradual. The fossil record is now sufficiently complete tha tthe boundary between Pelycodus and Notharctus is necessarily arb itrary . Onemorphological characteristic, acquisition of symphyseal fusion , appears to coincideapproximately with the Wasatchian-Bridgerian early Eocene-middle Eocene)bou ndary . The evolution of early Eocene Copelemur appears to have paralleledthat of Pelycodus, bu t detailed evidence is not ye t available. The origin of middleEocene Srnilodectes is not yet clear, but an origin from Pelycodus frugivoms orPelyco dus jarrovii appears likely.


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P. D. GINGER ICH and E. L. SIMONSINTRODUCTION

Pelycodus is the earliest member of th e primate family Adapidae. It is known from North Amer-ica and from Europe. Pelycodus appeared on bo th continents at about the same time arly in theYpresian in Europe, and at the beginning of the Wasatchian in North America. On the basis largelyof the presumed relationship of Adapidae to Lemuroidea and Lorisoidea, it has been suggested thatAdapidae possibly originated in Africa (McKenna, 1967, et al. . However, the primate fossil recordof Africa is still very limited. In Eurasia, l l of the Eocene Adapidae appear possibly to have beenderived from Pelycodus (Gingerich, 1977a,b), and the same can be said of the Adapidae found inNorth America. The North American adapid subfamily Notharctinae evolved indep enden tly of theEuropean subfamily Adapinae, but both can be traced back to the common ancestral genus Pely-codus. Opening of the North Atlantic Ocean in the early Eocene (McKenna, 1975) appears to havebeen responsible for this geographic separation and independent evolution.Pelycodus is important for another reason. It has one of the best stratigraphic records of anymammal yet studied, and it thus provides additional perspective on evolutionary patterns in mam-mals. To unders tand the evolution of a mamm alian lineage through a significant amount of geologicaltime requires (1) a sound stratigraphical framework based ultimately on measured stratigraphic sec-tions, (2) a detailed study of the distribution of variation of morphological characteristics withineach fossil sample, and (3) integration of ll fossil samples into the given stratigraphic framework.This stratophenetic approach to the study of phylogeny and evolution is discussed at greaterleiigth in Gingerich (1976b). Without going in to details of the method , we shall employ it here andamply dem onstra te its utility where the fossil record is as dense and continuous as it is for NorthAmerican Pelycodus, a stratophenetic approach yields an almost direct reading of genealogical rela-tionships and th e evolution of morphological adaptations.We first outline the stratigraphic and geographic framework for this study , describe denta l varia-tion in Pelycodus, review and revise the systematic nomenclature of early Eocene Adapidae, and inthe final section consider evolutionary patterns in the evolution of North American Pelycodus andCopelemur with a brief consideration of the origin of middle Eocene Smilodectes and Notharctus.Abbreviations used herein are as follows: ACM, Pratt Museum of Geology, Amherst College(Amherst, Mass.); AMNH, American Museum of Natural History (New York); KU, University ofKansas Museum of N atural History (Lawrence); PU, Princeton University Museum of Natural History(Princeton, N. J. ; UCM, University of Colorado Museum (Boulder); UM, University of MichiganMuseum of Paleontology (Ann Arbor); USNM, National Museum of Natural History, SmithsonianInstitution (Washington); UW University of Wyoming Geological Museum (Laramie); and YPM,Yale Peabody Museum (New Haven, Ct.).

STRATIGRA PHIC AND GEOGRAPHIC FRAMEWORKThe stratigraphic framework for this study was outlined in Gingerich (1976a, p . 4-9). To reviewand bring that summary up to date, in 1962 one of us (E. L. S.) began an intensive annual summer

program to collect fossil mammals in the lower Eocene Willwood Formation of the central Big HornBasin in no rthwestern Wyoming. Most of these collections came from a geographic area some 40 krnby 50 krn on a side. All mammals collected up to , and including, 197 3 are in the collection of thePeabody Museum of Natural History at Yale University. In 1974 , a joint Yale University-Universityof Michigan team under the direction of the authors continued this work in the central Big HornBasin. All mammal fossils collected in 19 74 (excep t the primates, which are at Yale) are in thecollection of the Museum of Paleontology a t the University of Michigan. Collections made by Yale


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EARLY EOCENE ADAPIDAE 247University parties subseque nt to 197 4 have no t been included in this report. A small collection ofLysite mam mals was made by a University of M ichigan field party in 19 76 in the vicinity of RedButte in th e central basin, part of which has been included in this study. To date, a total of over 400fossil localities (numb ered from 1-434) have been discovered in the centr al Big Horn Basin.

In 196 5, Grant E. Meyer and Leonard Radinsky measured a stratigraphic section approx imately1800 ft . (550 m ) thick across the entire study area. This section forms the basis for most of theanalysis of Pelycodus presented here. Some 8 4 localities were tied directly in to the original sectionby Meyer and Radinsk y. Anoth er section measured subsequently by Neasham and Vond ra added 1 9more localities t o th e basic section. The remainder of th e localities yielding Pelycodus that areincluded in this analysis were interpolated into the basic section using both geographic proximityto localities already in the basic section and comparison of the average size of the given Hyopsodussample t o tha t from nearby localities. The final com plete stratigraphic sequence of localities is givenin Gingerich (1976a, fig. 2). In 197 6, David Shank ler and Sco tt Wing of Yale University began meas-uring new stratigraphic sections in the ce ntra l Big Horn Basin to co rrela te all of the fossil localities onthe basis of stratigraphy alone. Thus, hopefully, there will be n o need in the future t o interpolatelocalities based o n the morphology of Hyopsodus The new stratigraphic study is unlikely t o changeour u nderstand ing of th e relative position of localities very significantly, and we have thus continuedt o use the basic sections measured earlier by Meyer and Radin sky.

Some results are included here based on recent w ork by 197 5 and 19 76 University of Michiganfield parties working in th e Sa nd Coulee area of t h e Clark s For k River drainage in th e nor ther nBig Horn Basin. All of the described specimens of Sand Coulee Pelycodzrs came from localitiesactually in measured stratigraphic sections.

The geographic distribution of North American localities yielding Pelycodus is shown in text-fig. 1. The areas yielding the biggest collections are th e San Jua n Basin of New Mexico; th e Fo ur Milearea in no rthe rn Colorad o (McKenna, 196 0); th e Washakie Basin (Gazin, 19 62 ; Savage et al., 1972);the Wind River Basin (Guthrie, 196 7, 1971); th e Big Horn Basin and the Powder Rver Basin (Delson,1971) of Wyoming. A small collection of Pelycodus trigonodus from the Golden Valley Formationin southwestern North Dakota (Jepsen, 1963) is the only North American sample from outside ofthe m ap area shown in text-fig. 1.During t he Paleocene and Eocene, erosion of th e mou ntains an d aggradation of the basins in west-ern North America kept pace and maintained a fairly mature topography (Van Houten, 1944).Thus, there was relatively little faunal endemism within sedim entary basins. The species of Pelycodusfrom New Mexico appear to have been virtually identical t o their correlative cou nte rpa rts in Wyo-ming, and there is no evidence that any part of the known geographic range of North AmericanPelycodus was isolated for a significant time from any other part (although some disruption of largepopulations by rivers and other natural barriers was probable; also, as mentioned above, Europeanspecies of Pelycodus were early isolated from the North American species). Wherever the y have beenstudied t o d ate, North American species of Pelycodus appear to fit into the patterns presented herebased on Big Horn Basin collections. Copelemur appears also t o have had a broad geographic distri-bution in N orth America (it is no t known from Europe), b ut Copelemur is most com mon in southernfaunas. It became established in th e Big Horn Basin onl y during the latt er part of the Lysite andearly Lost Cabinian. Climate and ecology were undo ubt edly responsible for the more limited distri-bution of Copelemur

DENTAL VARIATION IN P L YCODUSThe dentition is probably the most important single anatomical system in living mammals for

system atic and evolutiona ry stu dy. Most living mam mals can be ide ntified t o genus or species from


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P. D. GINGERICH and E. L. SIMONS

TEXT-FIG. 1 Sketch map of Rocky Mountain intermontane basins in the western United States showing thegeographic position of localities mentioned in the text. elycodus is also known from NorthDakota and it gave rise to a major radiation o f Adapidae in Europe. The occurrence of some ofthe same species n localities ranging from the Big Horn Basin to the San Juan Basin suggests thatearly Eocene populations of elycodus enjoyed a broad pangeographic distribution possiblycovering most of the western United States. Figure from Van Houten 1945).


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EARLY EOCENE ADAPIDAE 249TABLE 1 Summary of measurements of the lower and upper cheek teeth of elycodus ralstoni from Universityof Michigan Locality SC-4 in the Sand Coulee area, northern Big Horn Basin, Wyoming. M Depth is

depth of mandibular ramus measured below MI; L ength; W, width; n, sample s i z e ; E , observed range;x sample mean; s, standard deviation; y coefficient of vGiation; T oefficient of variation of logL x W) at each too th position. Measurem ents in mm .

M. Depth 4 7.0 8.5

their teeth alone. Thus the fact tha t many fossil mamm als, including elycodus and Copelemurare know n primarily from their teeth and jaws is no t th e handicap for systematic and evolutionarystudies that it might at first appear to be. Other anatomical systems in these extinct genera, forwhich we have little or no knowledge, were undoub tedly evolving along with th e dentition. However,if only one anatomical system could be chosen for evolutionary study , the de ntition would probablybe the first choice, and it is indeed fortunate that this is the system preserved in the fossil record.Teeth are involved in the m astication of food , and the complicated pattern of cusps and crests charac-teristic of the teeth of different mamm alian groups reflects the dietary preference of the group as


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250 P. D. GINGERICH and E. L. SIMONSTABLE 2 Summary of measurements of the lower cheek teeth of Pe ycodus mckenn i sp. nov. from Yale Lo-cality 6 in the central Big Horn Basin Wyoming. Abbreviations as in Table 1 Measurements in mm.

well as its heritage . The fact t ha t there is a single definitive set of permanent teeth th at form withinthe jaw before they erupt is of great importance because it removes the necessity to correct toot hmeasurem ents for on togenetic change in size. Within groups of related mam mal species, bo dy sizeis highly correlated with tooth size. In primates, for example, the correlation of tooth length withbody weight has been estimated at .956 by Kay (1975), and similar values obtained for other toothsizelbody size correlations in m ammals (Gou ld, 19 75 ; Gingerich, 1976b). To oth size, like body size,varies within recognized limits w ithin a living species, and th is variance has a high additive geneticcom ponen t (i.e., high heritability, Bader, 1965). In sum, the insight tha t teeth offer for comparisonsof changes in body size, and for study of dietary ad apta tions mak e them ideal for detailed evo lution-ary studies.We have measured all of the te eth from two of th e largest samples of Pelycodus fro m single locali-ties, and these measurements are summarized in Tables 1 and 2. The coefficient of variation of to ot hsize in these single loca lity samples is well within the range of variability of living primates (Gingerich,1974).The distribution of variation in size of the first lower molar in three fossil samples is comparedto the distribution in two living species in text-fig. 2 The major difference between the two livingMadagascar indriids Av ak i laniger and Propithecus diadema is a difference in body size, Propithecusweighmg about four times as much as Avahi This body size difference is accurately reflected in thedifference in tooth size seen in text-fig. 2. Similarly, the m ajor difference between the extinct speciesPelycodus ralstoni and Pelycodus abditus was probably one of overall body size also. Judging fromthe difference between the sizes of teeth characterizing the two, P abditus probably averaged abou ttwice the body weight of P ralstoni Adapis magnus is a European adapid species tha t is included intext-fig. 2 for com parison, but will no t be furth er discussed here (see Gingerich, 1977a,b).Body size is pro bably the most imp ortan t single dimension in determining an animal s adaptation.Given the ecological and physiological importance of body size (see Hutchinson and M cArthur, 19 59 ;McNab, 1971 ; etc.), we have con centrated on body size in th e following analysis of evolutionary


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EARLY EOCENE ADAPIDAE

Propithecus diademan = 4 2 . P = 1536s = ,045, V = 2.9

10 vahi lanigern.31, P = 1.102s = ,042, V= 3 8

LOG L x OF MI

.

TEXT -FIG. 2 Dental variation in tw o living species of lemuriform Indriidae Avahi and Propithecus) comparedwith dental variation in three species of Eocene lemuriform Adapidae Pelycodus and Adapis ,each fossil sample from a single locality). No te similar coefficients of variation in living andfossil samples. Use of log M I size is justifie d in Gingeri ch 1 9 7 4 ) . Locality SC-4 is at level 210 min text-fig. 11. Locality Y-M-45 is the type loca l i ty of Pelycodus abditus , at level 11 40 ft intext-fig. 10 .

Pelycodus ralstoni SC-4 Pelycodus abditus Y-M 45) dapis magnus EUZET 1n.13, X .069 n.13, P=1309 n.23, P 522s = ,038, V= 3-5 s = ,038, V = 2.9 s = -036, V = 2 4

change in Pelycodus. Other characters, such as mesostyle and hyp oco ne de velopm ent, have beenstudied w henever possible, b ut the fact remains t ha t t he most significant way that successive speciesof Pelycodus differ is in too th size and, by inference, body size.

SYSTEMATIC REVISIONThe evolutionary patterns outlined in the following section of this paper were originally deter-

mined from a study of the fossils and stratigraphic framework before any species names were (orcould be) applied to the patterns. Once the patterns were known, it was possible t o search the litera-ture, compare the various available species types, and apply names to successive segments of theevolution ary lineages. Since use of the valid names will facilitate subsequent discussion, we presentthe systematic revision before the evolutionary patterns, although the latter formed the basis of thesystematic revision.

ll of the available species names for North American Pelycodus and the new genus Copelemurare listed in Table 3. It should be noted t hat we studied the entire typodigm (the entire sample ofa species fro m its t ype locality) whenever possible, an d this population sample was used for compari-son whe n identifying our collections to species. Th e typ e locality and minim um sample size studiedfor each typodigm are listed in Table (note tha t the given n includes only th e specimens tha tpreserved M ). Eight early Eocene species of North American Adapidae were generally recognizedas valid before this stu dy , and we now recognize te n species as valid. While we have described severalnew species, we have n ot in a ny way changed the basic concept of wha t constitutes a species in theseearly prim ates th e average duration o f a species remains essentially unchanged since Matthew s1915) revision. In recognizing tha t Gray Bull beds mak e u p almost half of the Wasatchian, during

which Pelycodus changed very significantly, we feel justified in describing one new species inter-me diat e between two of th e previously recognized species.


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EARLY EOCENE ADAPIDAEPelycodus Cope, 187 5

Prototomus (in part), Cope, 18 74 , p. 1 4.Pelycodus Cope, 1875, p. 13. Type: Prototomus jarrovii Cope.Tomitherium (in part), Cope, 187 7, p. 137 .Notharctus (in part , Osborn, 1902, p. 1 95.antius Simons, 196 2, p. 5. Type: Protoadapis eppsi Cooper.North A merican species.- Pelycodus ralstoni Matthew, P. mckennai, nov., P. trigonodus Matthew,P. abd itus, nov., P. figiv on ts Cope, P. jarrovii (Cope).European species.- Pelycodus eppsi (Cooper), Pelycodus savagei Gingerich.Known distribution .- Early Eocene (Wasatchian) of North America, and early Eocene (Ypresian)of Europe.Diagnosis.- Species of Pelycod us differ from contem poraneous species of Copelemur in havinga more closed talonid basin on the lower molars, usually lacking a notch o r valley between the en to-conid and hypoconulid, and differ from all contem poraneous species of Cope lemur, except C tutus,in being significantly larger. Differ from species of later Notharctus in lacking symphyseal fusion.Differ from species of Smilodectes in having less compressed lower premolars and more distinctparacon ids on the lower molars.Discussion.- In the past, Pelycodus and No tharctus have usually been distinguished by the degreeof development of the hypocone and mesostyle on th e upper molars (see Osborn, 1902; Matthew,1915). The development of both hypocones and mesostyles in the evolution ofPelyc odus was verygradual, and placing the species f?ugivonts = nunienus) and jarrovii = venticolis) in Notharctus onthis characteristic is unnatural in that it implies a diphyletic origin of Notharctus (see text-figs. 10,13). It also has th e effect, given our present understanding of the synonom y involved, of placing thetype species of Pelycodus in the genus Noth arctus. An equally arbitrary, but more natural and stablediagnosis of Pelycodus and Noth arctu s involves placing the early Eocene species in Pelycodus, and th emidd le Eocene species in No tharctus . Sym physeal fusion of the mandibu lar rarni provides a usefulmorphological character for separating the two and this is the basis of t he diagnosis proposed here:Pelycodus lacks symphyseal fusion, whereas the left and right mandibular rami are coossified inNo tharctus. Undoubtedly, samples intermediate between Pelycodus jarrovii and Notharctus tene-brosus or Notharctus pugnax will be found in which some specimens within a single species have

fusion while others do no t. This illustrates the arbitrary nature of separation of the most advancedspecies of Pelycodus from the most primitive species of Notharctus. At the present time, lack ofsymphyseal fusion is the most useful characteristic diagnosing Pelycod us from No tharctus.In an earlier paper, Gingerich (1976a) extended the stratigraphic range of North American Pely-codus back in to the Clarkfork ian. That exten sion of range was based on an uncatalogued PrincetonUniversity too th of Pelycod us labeled in pencil as coming from the Paint Creek locality (Univ.Michigan Loc. SC-143). The toot h in question is too large to belong to Pelycodus ralstoni (seeGingerich, 1976a, fig. 7), th e earliest species from N orth America, and we suspect tha t the specimenin question is mislabeled. Higher stratigraphic levels are exposed in the vicinity of Paint Creek that doyield Pelycodu s. Recen t intensive collecting at locality SC-143 has resulted in a good Clarkfork ianfauna with no trace of Pelycod us. Two seasons of collecting in th e Sand Coulee area by University ofMichigan parties has established clearly that the Sand Coulee fauna with Pelycodus ralstoni overliesbeds yielding a Cla rkforkian fauna. The tw o faunas are distinctive, and Pelycod us has never beenfound in th e lower one.


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P. D. GINGERICH and E. L. SIMONSPelycodus ralstoni Matthew, 19 15

Pelycodus ralstoni Matthew, 1915, p. 436, fig. 4-6.Pe ycodus ralstoni (in part), Dorr, 1952, p. 90.

Type.- M 16089 , a right maxilla with P 4 - ~ 3rom 3 miles southeast of the mo uth of Pat0 ' H a ~ aCreek in the Clark Fo rk or Sand Coulee drainage basin, northwestern Wyoming. Theexact locality of origin of this sample has not yet been relocated, but study of archives at the Ameri-can Museum of Natural H istory suggests that th is is in th e vicinity of University of Michigan localitiesSC-89 and SC-139.Diagnosis.- Smallest North American species of Pelycodus, differs from P. mckennai and laterspecies in being significantly smaller, almost always lacking any hypocone development or meso-style crest, and in having a narrower, more rounded heel on M3. North Am erican Pelycodus ralstoniclosest to P. eppsi in Europe, appears to differ from it in lacking incipient hypocone on basal cingu-lum of latter. Also, type sample of Pelycodus eppsi falls at the very lower end of the size range inthe typodigm of P. ralstoni.Age and Distribution.- Lowest Wasatchian faunal interval, Sand Coulee beds and equivalent,known from northwestern W yoming.Description.- New collections made b y U niversity of Michigan field parties in the past two yearshave greatly increased the number of specimens and knowledge of the dental morphology of Pely-codus ralstoni. The lower dental formula of Pelycodus ralstoni is 2.1.4.3, and the upper formula ispresumably the same. UM 66365 preserves partial alveoli for a small I, and a larger 12, he root ofthe lower can ine, and roots or crowns of all four premolars. The mandibular symphysis in thisspecimen, as in all later Pelycodus as well, was unfused.One mandible, UM 648 28, preserves the lower canine intact. The lower canine in this specimenof Pelycodus resembles the lower canine of a male squirrel monkey Saimiri) in size and morphology,having a poin ted tip projecting vertically about 5.5 mm above the base of the enameled crown. Theroot of the canine was much larger than the crown, being larger in both maximum diameter and rootlength (about 7 mm long). Thus the crown and crown/root relationships in the earliest adapidPelycodus are very different from those in the earliest North American omom yid Teilhardina ameri-cana, which has a more premolariform crown set on a relatively much smaller root (Bown, 1976).Both could plausibly be derived from an ancestor like early Paleocene Purgatorius (Clemens, 1974),but Adapidae and Omomyidae show considerable subsequent divergence in anterior dental mor-phology. A long wear facet down th e back of the crown indicates that th e lower canine of Pelycodusralstoni occluded in fron t of a similarly projecting, interlock ing upper canine. Specimen U 66365has a significantly smaller canine root than U 64828, suggesting that some sexual dimorphism waspresent even in the earliest Adapidae. The canine morphology and occlusion characteristic of Adapi-dae and most anthropoid primates were present in the earliest adapid for which canines are known.Several specim ens (e.g., UM 648 28, 66365) preserve the ro ot of P I , and it is consistently single-rooted, but no specimens have yet been found preserving the crow n. The remainder of the dentitionhas been adequately described by M atthew (1 9 15).Measurements of the first lower molar of the type sample of Pelycodus ralstoni are summarizedin Table 3 (see also text-figs. 2, 10-13). Measurem ents of a somewhat larger sample from SandCoulee locality SC-4 are summarized in Table 1.

Discussion.- In addition to the sample from the Big Horn Basin described by Matthew (1915),the species Pelycodus ralstoni has been recognized in the Hoback Basin of western Wyoming. Speci-men UM 27243 figured and described by Dorr (1952) is M3 of the artiodactyl Diacodexis, but


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TEXT-FIG. 3 Ty pe specimen of Pelycodus mckennai UM 67 11 3 from L ocality SC-133, a left maxilla in A)lateral and B) occlu sal views.

another mandible fragment found among the unidentified teeth from Dorr's Hoback FormationLocality 2 does appear to belong to Pelycodus ralstoni. The new specimen, a left mandible fragmentwith P4 -M I is now catalogued as UM 67569.

Typodigm.- The following specimens of Pelycodus ralstoni are known from the type locality:AMNH 16088, 16089 (type), 16090, 16091, 16093, 16095-16097 94313 94316 94405 944089442 1 ,9443 4 .Numerous additional specimens of this species are present in the AMNH, UM and PU collections.Pelycodus mckennai new species

Text-figs. 3 , 1 3Pelycodusralstoni McKenna, 1960, p. 76. Dorr and S teidtmann, 197 1, p. 26. Delson, 197 1, p. 339.Pelycodus cf. ralstoni Wilson, 195 5, p. 5 14 fig. 1-2.

Type.- UM 671 13, a le ft maxilla with M ' - ~ ,ollected in 1976 by K. D. Rose from UM localitySC-133 in the Sand Coulee area (NE% , S1 , T55N, R102W, Park C o., Wyoming).Diagnosis.- Differs from Pelycodus ralstoni n being significantly larger and in having a relativelybroader heel on M3. Differs from other species of Pelycodus in being smaller and in having nomesostyle crest, or a small mesostyle crest present at low frequencies in samples from individual

localities.Etymology . Named for Dr. M. C. McKenna, American Museum of Natural History, in recognition

of his many contributions t o th e study of Eocene primates and oth er mammals.Age and Distribution.- Lower Wasatchian faunal interval, lower Gray Bull beds and equivalent,known from northern Wyoming (Powder River Basin, Big Horn Basin, Hoback Basin) and northernColorad o (Four Mile fauna).Description.- The dental morphology of this species is very similar t o tha t described above for

Pelycodus ralstoni the tw o differing only as no ted in th e diagnosis. Nevertheless, Pelycodus mc-kennai is distinctive and can be relatively easily distinguished from P. ralstoni and P. mgonoduswhen a representative sam ple is available. To oth measurements fo r the typodigm are given in Table 4.


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256 P. D. GINGERICH and E. L. SIMONSTABLE 4 Summary of measurements of the lower and upper cheek teeth of elycodus mckennai from the typelocality University of Michigan locality SC-133 in the Sand Coulee area northern Big Horn BasinWyoming. Abbreviations as in Table 1. Measurements in mm.

Lp2 WLp3 WLp4 W

M1 W

M WLM3 W

M . Depth

One exceptionally complete mandible, PU 17417 from the Hackberry Hollow locality, is worthyof n ote . It preserves alveoli for a small central incisor, a slightly larger lateral incisor, a canine measur-ing 2.3 by 1.7 mm at the base of the crow n (most of the crow n itself is missing), the in tact crow n ofP I , roots for P2 nd the remainder of the teeth intact (MI broken). By comparison with UM 65304,a presumed male of P rnckenn i with a canine crown measuring 2.8 by 2.3 mm at the base, thePrinceton specimen would appear t o be a female.A maxilla of P mckenn i (UM 6326 6) collected by W. Jungers retains alveoli for the upper canineand PI- , and the cheek teeth P 3- 4, M ~ - ~Five mandibles UM 65686, 66249, 67089, 67513,


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EARLY EOCENE ADAPIDAE 257PU 17417) show that a total of four premolars were present in each lower jaw. U 66940 is acrushed partial skull of this species including the left occiput and mastoid region, and a portion ofthe left auditory region, but it has no t ye t been cleaned sufficiently to describe here.Discussion.- McKenna (1960 , p. 76 ) tentatively synonymized Pelycodus ralstoni and P. trigono-dus because a sample he studied from the Four Mile area of northw estern Colorado was intermediatebetween the two. McKenna recognized that only a detailed biostratigraphic study of Pelycodusspecimens from Willwood Forma tion of the Big Horn Basin would determine the validity of P. trigo-nodus. Now that such a study has been completed, it is clear that both Pelycodus ralstoni andPelycodus aigonodus are valid and tha t an intermediate speciesP. mckennai is sufficiently distinctiveto w arrant recognition. A sample of specimens (numbered AMNH 936 56, 93 657 , 9366 1) from theEast Alheit locality (Four Mile fauna) was studied in detail, and it matches the type sample of P.mckennai from the Big Horn Basin almost exactly. Twenty-one first lower molars have a mean valuefor the log (L x W) of MI of 1 I47 (OR 1.08-1.20, s .03 1). Of the ten upper molars studiedfrom East Alheit, eight had no trace of a mesostyle, two had a very weak mesostyle crest, and nonehad a distinct mesostyle.Two upper molars, UM 59895, 59899, described by Dorr and Steidtmann (1971) from Locality29, Sublette County, Wyoming, appear to belong to Pelycodus mckennai rather than P. ralstonibut the specimens by themselves are inadequate fo r certain identifica tion . They both measure4.0 mm in length, which accords better with P. mckennai than P. ralstoni and both lack any trace ofa mesostyle. Similarly, the size measurements given by Delson (1 97 1) for Pelycodus from the PowderRiver Basin, if all are from the same restricted stratigraphic interval, indicates that they representP. mckennai rather than P. ralstoni.Wilson (1955) described an interesting anomaly in a specimen of P. mckennai (KU 8 508) from theBig Horn Basin he specimen apparently has a smaller supernum erary Mg following the normal Ms.A similar anomaly has recently been noted by one of us [P. D. G.] in a specimen of European Adapis.Typodig in-- The sample from the type locality consists of the following specimens: UM 67087,670 89,6 710 2,67 107 ,671 13 (type), and 67123.In addition, large collections of this species from lower Gray Bull localities are in the AMNH,PU, UM, YPM, and othe r museums.

Pelycodus trigonodus Matthew, 1915

Pelyco dus frugivorus Osborn 1902 p. 193 fig. 21. Loomis 1906 p. 281 fig. 3Pelycodus trigonodus Matthew, 1915 p. 436 fig. 7-8.Pelyco dus frugivorus (in part), Matthew 1915 p . 439 fig. 12-14.Pelycodus cf. trigonodus Gazin, 1962 p . 27.Pelycodus cf. ralstoni Jepsen, 1963 p . 679. West 1973 p. 750.

Type.- AMNH 15017, associated upper and lower jaws, from American Museum Dry Camp 1,Big Horn Basin, 1910 expedition, a locality approximately 5 miles south of Otto , Wyoming.Diagnosis.- Differs from Pelycodus ralstoni and P. mckennai in being larger, and having a smallto medium mesostyle crest. Differs from P abditus and P. jarrovii in being smaller, differs from

P. abditus P jarrovii and P. frugivoms in having less well developed mesostyles and generally lackinghypocones.Age and Distribution.- Middle Wasatchian faunal interval, upper G ray Bull beds and equivalent,known from western North Dakota (Golden Valley Fm.), northwestern Wyoming (Big Horn Basin),and southwestern W yoming (Washakie Basin).


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r r

TEXT-FIG: 4 Right maxilla of Pelycodus trigonodus PU 14515 in lateral view showing first evidence that apostorbital bar was present in this species

Description.- s is the case in the transition from Pelycodus ralstoni to P. mckennai the transi-tions from P. rnckennai t o P. trigonodus and from P. trigonodus to P. abditus appear to have beencon tinuous and gradual. Thus the boundary between each successive species is necessarily arbitr ary.Nevertheless, P trigonodus represents a distinctive stage of evolution in Pelycodus that can be recog-nized, given adequate samples, by its characteristic size range and molar construction. The uppermolars generally have a mesostyle crest but lack hypocones, retaining instead the broad postproto-cingulum th at characterizes early species of Pelycodus.PU 145 15 is a badly broken partial skull of Pelycodus trigonodus collected from the McCulloughPeaks by F. B. Van H outen in 1937. This specimen preserves muc h of the upper molar series, but itis most important in showing that Pelycodus had a fully developed postorbital bar (text-fig. 4), asin later Notharctus and other A dapidae.Discussion.- Loomis (1906) described and figured the first specimens of this species from theBig Horn Basin. His figure 3 is an illustration of ACM 3 41 4.Gazin (1962) referred specimens of Pelycodus from Bitter Creek in southern Wyoming to thisspecies. We have studied tw o of these, mand ibles YPM 140 68 and 152 85 , which were bo th co llectedby Smith and Heisey for 0 C. Marsh in 1882 from the light colored beds. Both appear to bealmost identical with the type specimen of P. trigonodus and the one preserved M1 has a log (L x W)1.20, matching th at for the type sample ofP trigonodus.Jepsen (1963, see also West, 1973) listed the species Pelycodus cf. ralstoni in h is faunal list fromthe Golden Valley Formation in North Dakota. This record is based on three isolated tee th: anupper M2 (PU 17234) measuring 4.3 rnrn in length, 6.8 mm in wid th; an uncatalogued M1 m easuring4.1 m m in length and 5.7 mm in width ; and an M, (PU 17269) measuring 4.7 mrn in length and4.3 mm in width. These teeth resemble P. trigonodus most closely in size and in having a small tomedium-sized mesostyle crest on the upper molars, and they are here referred to P trigonodusrather than P. ralstoni.


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EARLY EOCENE ADAPIDAE 259TAB LE 5 Measurements of the type and a referred specimen of Pelycodus abditus. Measurem ents in mm.

UM 66000 (type)Mandibular dentitionToo th Length Width

AMNH 15018Maxillary dentitionTooth Lengthp3 4.1p4 4 oM' 4.7M~ 4.9M 4.3

Width

estimated

Typodigm.- The type sample consists of some seven mandibles, a maxilla, and a cashed palate:AMNH 15017 ( type), 1 5029 ,1505 0,1505 4,150 57, and 16152.In addition, there are numerous referred specimens of this species in the AMNH, PU, UM, YPM,and oth er museum collections.Pelycodus abditus new species

P1. 1 fig. I ; text-fig. 1 3Pelycodus nuniensis Loomis, 1 906 , p. 28 2, fig. 5.Pelyco dus jarrovii (in part) , Matthew , 1915, p. 438, fig. 9, 10.Pelycodus cf.jarrovii Kelley and Wood, 195 4, p. 344, fig. 4d .Pelycodus near jarrovii Gazin, 196 2, p. 28.

Type.- UM 66000, right and left mandibles collected by G. Gunnell and B. H. Smith from Yale-Michigan Locality 45, southwest of Red Butte in Section 33, T49N, R95W7Big Horn C ounty , Wyo-ming.Diagnosis.- Differs from Pelycodus ralstoni P mckennai and P. trigonodus in being larger, hav-ing a stronger mesostyle, an d usually a distinct bu t small hypocon e. Differs from P. fmgivomsin being larger bu t having a less well developed mesostyle a nd hypocon e. Differs from P. jawoviiin being smaller and having a less well developed mesostyle a nd hy pocone .

Etymology.- abditus L., hidden or concealed, in reference to the long period during which thisspecies was incorrectly hidden under the name P. jawovii.Age and Distribution.- Upper Wasatchian faunal interval, Lysite beds and equivalent, knownchiefly from northwestern Wyoming (Big Horn and Wind River Basins), but also from southwesternWyoming (Fossil Basin).

Description.- The type specimen of Pelycodus abditus a mand ible, is illustrated in Plate 1 , fig. 1,and one of the best upper dentitions is the maxilla AMNH 15018 illustrated by Matthew (1915,fig. 9). Measurements of these specimens are given in Table 5 . Measurements of M1 in the typodigrnare summ arized in Table 3


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26 P D GINGERICH and E L SIMONS

EXPLANATION OF PLATEAll figures twice n atural size)

Figure Type specimen of Pelycodu s abd itus, UM 66000, left and right mandibles in occlusal view, stereophoto-graph.Figure 2 To poty pe of Pelycodus jarrovii, AMNH 16298 left mandible with in occlusal view, stereo pho to-graph.Figure 3 To poty pe of Copelem ur tutus, AMNH 162 06, left mandible with M I 2 in occlusal view, stereophoto-graph.


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EAR LY EOCENE ADAPIDAE

LARGO and ALMAGRE c tutusLARGO- . consortutus P frugivorus TYPE' P jarroviil m l n B ALMAGRE

-TYPE ~~~~

LOST CABINC consortutus frugivoru s ja rro vi i

0 1.10 1.20 1.30 1.40 1 50LOG LxW) OF MI

TEXT-FIG. 5 Comparison of the pattern of variation in tooth size in early Eocene Adapidae from the San JuanBasin Largo and Almagre beds) with that in the Wind River Basin Lost Cabin and Lysite beds).Two species are present in the Lysite beds, and three are present in the Lost Cabin beds in theWind River Basin. Samples from both the Largo and Almagre facies match Lost Cabin adapidsmost closely in size shown here) and other morphological characteristics. Type specimens areindicated whenever possible. Open squares are estimates based on M where M is not preserved.Evidence for phylogenetic relationships shown by arrows is shown in text-fig. 10.

The typ e specimen (Pl. 1 , fig. 1) consists of left and right mandibular ram i, narrowing at the frontto form a V-shaped mand ible with an unfused symphysis. Roo ts and/o r too th crown are preservedfor th e canine, fo ur permolars, and three m olars in t he type. YPM 26 52 4, an early representative ofP. abditus from Yale Locality 26 8, preserves alveoli showing th a t there were clearly tw o small incisorsin the mandible of this species, the central one being slightly smaller than the lateral on e.

The upper dentition of Pelycodus abditus (text-fig. 13) is distinctive chiefly because it has a dis-tinct m esostyle crest and a small bu t distinct hyp oco ne o n the uppe r molars.

Discussion. The first description and illustration of specimens of Pelycodus abditus was earlyin this centu ry by Loom is, wh o published a figure of ACM 35 42 (Loom is, 19 06 , fig. 5). Loom isdescribed these under the name Pelycodus nuniensis Cope, an obvious lapsus calami for Cope'sPelycodus nunienus (see below).

An additional confusion regarding this species was created inadvertently by Matthew (1915),who designated a specimen (AMNH 15018) of this species as a neotype ofP ely co du s arrovii. Cope(1874) originally described P. jarrovii from New Mexico, but the type specimen was lost sometimebefore M atthew's revision. No collections from t he Almagre and Largo beds of New Mexico includeth e species represented by AMNH 1501 8, althou gh Lost Cabin age specimens of Pelycodus areclearly represented (tex t-fig. 5). As discussed below , P. jarrovii is a senior synonym of the speciesusually referred to under th e name P. venticolis. Hence it is necessary to redescribe the collections


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262 P. D. GINGERICH and E. L. SIMONSidentified by Matthew (1915) and subsequent authors under P. jarrovii as a new species, for whichthe name Pelycodus abditus is proposed.

Typodigm.- The type sample of P. abditus includes the following: UM 65956, 65960, 65984,6599 7, 6600 0 (type), YPM 1863 9, 18641-18644, 1864 9, 1867 9, 2321 8, 23284, 23285, 23323,24391,27 148,30425 ,31000,3101 0,31052, and 33293.Numerous additional specimens of this species are in the collections of ACM, AMNH, PU, UM,USNM, an d other museums, the collections from Lysite beds of the Big Horn Basin and WindRiver Basin (Guthrie, 196 7) being the mos t impo rtant.Pelycodus frugivoms Cope, 1875

Pelycodus frugivorus Cope, 1875, p. 14.Tomitherium frugivorum, Cope, 18 77 , p. 14 4, P1. 39 , fig. 1 6.Pelycodus nunienum Cope, 1881, p . 187.Pelycodus frugivoms, Cope, 1885 , p. 23 0, P1. 15a fig. 4-5.Notharctus nunienus, Osborn, 190 2, p. 195, fig. 20b, 22. Matthew , 191 5, p. 444 , fig. 19. Granger and Gregory,1917, p. 845.Notharctus lirnosus Gazin, 1 95 2, p. 22, P1. 1, fig. 6-8. Gazin, 19 62 , p. 2 9, P1.4, fig. 5.Notharctus cf. nunienus, Gazin, 19 62, p. 30.Notharctus nunienus (in part), Robinson, 19 66, p. 3 1, P1.8, fig. 3. Guthrie, 19 71 , p. 63 .Type.- Unnumbered mandible with M2-, in Cope collection from lower Eocene of New Mexico

(Almagre beds), ,specimen now lost. Cope (1875) gives measurements of the type as follows: M2length and width, 4.5 and 4.0 mm; M3 length and ki dt h , 6.0 and 3.5 mm. AMNH 1620 9 from NewMexico agrees very closely w ith these measurements. AMNH 1 621 2 appears to be the best topoty peof P fmgivoms collected to date.Diagnosis.- Differs from P. ralstoni and P. mckennai in being larger, from P. abditus and P arroviiin being smaller (see Table 3). Differs from P. ralstoni, P. mckenna i, P. trigonodus, and P. abditusin having stronger mesostyles (usually distinct cusps) and stronger hypocones.Age and Distribution.- Upper Wasatchian faunal interval, Lost Cabin beds and equivalent,known from northwestern Wyoming (Big Horn and Wind River Basins), southwestern Wyoming(Green River Basin), southern Colorado (Huerfano Basin), and northern New Mexico (San JuanBasin).Description.- The most com plete lower jaw of Pelycodus frugivorus, AMNH 12736 from the W i dRiver Basin, was figured by Matthew (1915 , fig. 19). It originally had a comp lete canine, and thecrowns of P2-M 3 nta ct (text-fig. 6c). At some time subsequently, before it was refigured by Gregory(1920, P1. 36), the crown of the canine and part of P were brok en and lost. Nevertheless, the speci-men shows the unfused symphysis, projecting canine, normally proportione d P4 with distinct para-conid and metaconid, molars with distinct paraconids, and closed talonid basins characteristic ofP. frugivoms. The tw o top otypes mentioned above, AMNH 1620 9 and 16212 from the San Jua nBasin, agree in most details, bu t have a slightly bette r developed entoconid notc h on M2 and a nar-rower rounded heel on M3. Com parison with oth er specimens from Lost Cabin beds of the WindRiver Basin (e.g., PU 20590) and USNM 19294 (holotype of N. limosus ) from the Green RiverBasin, indicates that an entoconid notch and rounded MJ heel also occur in some specimens fromWyoming.One of the best upper dentitions is a specimen, AMNH 4735 from the Wind River Basin, figuredby Cope in 1885 PI. 15a, fig. 4; see also Osbom , 190 2, fig. 20b; and Gregory, 1 920 , PI. 35, rev.).It shows very distinct m esostyle cusps, especially o n M 2, and worn but distinct hyp ocones.


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EARL Y EOCENE ADAPIDAE 263

N o 6 oA

A C consortutus B C tutus

N z 4 6 3 7D P jarrovII yP frugivorus 0 2 m

TEXT-FIG. 6 Comparison of the r ight m andibular dent i t io n of four species of Adapidae f rom the Almagre andLargo beds of th e San Juan Basin, New Mexico, al l draw n at th e same scale. A and B are Cope-lemur C an d D are Pelycodus. All specimens in AMNH. Drawings from M atthew 1915), lightlymo re th an twice natural s ize.

Discussion.- Cope described Pelycodus fmgivoms in 18 75 , based on a specimen from New Mexi-co. Five years later Wortman collected similar specimens in the Wind River Basin of Wyom ing, andCope (1881) named these P nunienus a name he subsequently synonymized with P. fmgivoms(Cope, 1885 ). The chief character tha t distinguished them was the twinned hypoc onulid on M,in P nunienus and its absence in P frugivoms. Cope (1885) concluded that this was probably justindividual variation, a conclusion further substantiated by the variation described above in WindRiver specimens.

Subse quently, Osborn (1902) and Loom is (1906) incorrectly identified specimens of P rigonodusas Cope s P fiugivoms and resurrected the name P nunienus for the more advanced Wind Riverforms with quadra te molars, shifting the species t o Notharctus o n this accoun t. This confusion of


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26 4 P. D. GINGERICH an d E. L. SIMONSP. frugivorus with P. trigonodus, and subsequently with Copelemur feretutus (see below), obscuredbo th the tru e relationships of the species and the correlation of New Mexico Eocene strata with thoseof Wyoming. Afte r restudying all of the collections available from New Mexico, including thosemade by Simpson in the late 1940 s and early 1950 s (Simpson, 19 48 , 1951), it is possible t o arriveat a clearer unde rstanding of th e New Mexico Adapidae.

Two species of Pelycodus and two species of the new genus Copelemur are represented (text-figs. 5, 6). P. fmgivoms occurs in both the lower (Almagre) and upper (Largo) beds of the SanJosC Form ation in New Mexico. It is mo st comm on in th e lower beds, and Almagre Arroyo wouldappear to be the type locality of P. frugivorus (Simpson, 1951, p. 16-17). Species of Pelycodusas advanced as those from the Almagre and Largo beds do not appear elsewhere until the equivalentof the Lost Cabin beds in Wyoming. For these and oth er faunal reasons, it appears likely tha t theAlmagre and Largo faunas are very close to each other in age, and correlative with the Lost Cabinbeds in n orthern Wyoming.The species Notharctus limosus occurs together w ith P. jarrovii in the Green River Basin (Gazin,1952) and it is morphologically indistinguishable from P. frugivorus, hence the two are almost cer-tainly synonym ous.Some specimens from the Huerfano lower faunal zone labeled Notharctus nunienus by Robinson(1966) belong to Pelycodus frugivorus, bu t Pelycodus jarrovii is also represented . Specimens fromthe upper faunal zone are no t included , and will be discussed elsewhere in connection with a revisionof Notharctus and Smilodectes.~ ~ ~ o d i ~ r n . -he exact locality where the type specimen of P. frugivorus was found cannot bedetermined, and the type itself is lost, but the following specimens representing this species werefoun d in the lower or Almagre beds in New Mexico: AMNH 1 62 12 ,4 89 56 , 48 95 9,5 55 06 ,55 5 12 ,55513. The following specimens of P. frugivorus come from the upper or Largo beds: AMNH16208 , 16209 , 55502 , 55503 .In addition, a large number of specimens of P. frugivorus are known from the Wind River Basin,including AMNH 4734 (type of P nunienus), 47 35 , 1 273 6, PU 1 836 6, and 20590. Other specimensof P. frugivorus include USNM 19 29 4 (type of P. limosus, from Green River Basin), YPM 27294(Big H orn Basin), and AMNH 55 22 4 and UCM 32 15 7 (Huerfano Basin). Additional specimens arehoused in all of the above museums.

Pelycodus jarrovii (Cope, 1874)P1. 1 , fig. 2 ; text-figs. 6 d, 7

Prototomus jarrovii Cope , 18 74, p. 14.Pelycodusjarrovii Cope, 1875, p. 1 4. Cope, 1881 , p. 18 7. Cope, 1 885, p. 228.Tomitherium jarrovii Cope, 1877, p. 13 7, P1. 39, fig. 17-18.Pelycodus tutus (in part), Cope, 1881, p. 187. Cope, 18 85, p. 228 , P1 25a, fig. 103. Osborn, 190 2, p. 1 94.Notharctus venticolis Osborn, 1902 , p. 195. Matthew , 191 5, p. 443 , fig. 16-18. Granger and Gregory, 1917,

p. 846. White, 1952 , p. 192 . Gazin, 1952 , p. 24.Pelycodus jarrovii (in part), Matthew, 191 5, p. 438.Notharctus cf venticolis Gazin, 1962 , p. 30.Notharctus nunienus (in part), Robinso n, 196 6, p. 31.Notharctus venticolis (in part), Guthrie, 1971, p. 63.

Type.-- Unnumbered mandible with broken M2 and intact M3 in Cope collection from lowerEocene of New Mexico (A rroyo Blanco), specimen now lost. Cope (1874) gives measurements ofthe typ e as follows: M2 width , 5.0 mm ; M3 length and wid th, 7.0 and 4.5 mm. This is the specimenfigured by Cope (1877) in his Plate 39, figure 17 . AMNH 16 29 8, a mandible with appears to


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TEXT-FIG. 7 Right mandible of Pelycodusjarrovii UW 1642, from the Red Desert area Sweetwater CountyWyoming. Specimen in A) occlusal (B) lateral and (C) posterior view. Inset shows the relativesize of the root of I and the alveoli for I2 and the canine in an enlarged oblique anterior viewlooking down the alveoli.

be the best topotype of P. jarrovii collected to date. No te tha t the specimen designated a neotypeof P. jarrovii by Matthew, 19 15 , belongs in fact to P. abditus.Diagnosis. Differs from all other species of Pelycodus in having a well developed mesostyleand hypocone on the upper molars.ge and Distribution. Upper Wasatchian faunal interval, Lost Cabin beds and equivalen t,known from northw estern W yoming (Big H orn and Wind River Basins), southwe stern Wyoming(Green River Basin), southern Colorado (Huerfano Basin), and northern New Mexico (San JuanBasin).

Description. One of the most complete mandibles ofPelycodus arrovii is UW 1642 (text-fig. 7 ,which preserves the roo t of a very small central incisor, the alveoli for a larger I ,, a still larger canine,and a small P I , as well as the intact crowns of P2-Mg The lower molars of P. jarrovii are broad andflat, resembling othe r species of Pelycodus. The sym physeal area in UW 164 2 is well preserved andthe rarni clearly were n o t coossified. The articular condyle is also well preserved in this specimen,and it has the bean-shaped appearance Gregory (192 0, p. 145) described in middle Eocene N otharctus. The canine alveolus in UW 1642 measures about 4.2 mm by 2.5 mm. By comparisonAMNH 14655, another mandible of P. jarrovii described by Gregory (1920, fig. 44-45 , has a stoutprojecting lower canine of much greater diameter, suggesting that the former is a female and thelatter is a male.

A crushed partial skull of P. jarrovii (AMNH 146 56) is kno wn f rom th e Wind River Basin tha tpreserves the upper incisors and upper canine (Gregory, 1920, fig. 31, 52). The central incisor hasa broad spatulate crow n, while the lateral one has a much sm aller and almost pointed crow n. Theupper canine in this specimen of P. jarrovii is a very large, narrow , dagger-like too th resembling tha tin males of highly d imorphic species of monkeys. The uppe r premolars and molars are typical of


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266 P. D. GINGERICH and E . L. SIMONSthose of most Pelycodus, except that the molars have prominent mesostyles and hypocones (text-fig. 13).

Discussion.- Cope s original type specimen of Pelycodus jarrovii consisted of a mandible fragmentwit h the talonid of M2 and a complete M3 from the San Jua n Basin of New Mexico. According t oSimpson (195 1, p. 14-15) it came from Arroyo Blanco. The type was illustrated by Cope (1877 ,fig. 17), bu t unfortunately was lost before any subsequent scholar was able t o study i t. Osborn(1902) hardly mentioned P. jarrovii in his paper describing Notharctus venticolis from the WindRiver Basin. Matthew (1915) might perhaps have recognized the synonymy of P arrovii and N.venticolis, but he misinterpreted the teeth preserved in a topotype of P. jarrovii (AMNH 16298),thinking th at the preserved teeth were M, and a broken M 3. They are in fact MI and M 2 , ndicatinga larger species tha n Matthew judged P. jarrovii t o be. Restudying all of the San Juan Basin Pelycodusand Copelemur, and p lotting them on a size axis (text-fig. 5), it is clear tha t AMNH 16298 (solidsquare at right) represents the same species as the type specimen of P. jarrovii (open square). Theonly possible confusion would be with Copelemur tutus, a species with very different molar mor-phology . Comparing the specimens of P. jarrovii from the Almagre beds of New Mexico with thosefrom the Wind River Lysite and Lost Cabin beds of Wyoming (text-fig. 5), it is clear that P. jarroviiis conspecific with Notharctus venticolis, from the Lost Cabin beds.Robinson (1966) described all the specimens of Adapidae from the Huerfano Basin as Notharctusnunienus, bu t i t appears tha t this is a mixed grouping. The smaller specimens from the lower bedsare Pelycodus frugivoms, whereas one larger specimen (AMNH 56546) from the lower beds is P.jarrovii. Specimens from the upper beds in the Huerfano Basin will be considered in a later study ofNotharctus and Smilodectes.A part of what Guthrie (1971) called Notharctus venticolis actually belongs to P. fmgivoms,while the larger spkcimens represent P. jarrovii.Typod igm.- Pelycodus jarrovii is a rare species in New Mexico, and only two specimens from thetyp e area are known in existing collections: AMNH 1 62 98 and AMNH 555 14 .In addition, we have studied many specimens of P. jarrovii in the ACM, AMNH, PU, UCM, UWand YPM collections. Others are preserved in the USNM. Some of the best specimens, in additionto the large American Museum collection and those described above, are ACM 10092, 10280; PU13424; 1344 5,1 836 7,2 059 2; and YPM 2 7788.

Copelemur, new genusTomitherium (in part), Cope, 1 877, p. 141.Pelycodus (in part), Cope, 1881 , p. 187.Pelycodus? Gazin, 196 2, p. 28.Notharctus in part), Guthrie, 19 71 , p. 63 .

Ty pe species.- Tomitherium tu tu m Cope.Included species.- Copelemur praetutus, (Gazin), C. feretutus, nov., C. consortutus, nov., andC. tutus (Cope, type species).Known distribution.- Early Eocene (Wasatchian) of North America. Copelemur appears to becharacteristic of more southern faunas within North America.Diagnosis.- Species of Copelemur differ from Pelycodus, Smilodectes, and Notharctus, in general-ly having an open talonid on the lower molars, with a more distinct entoconid notc h. All exceptC. tutus differ from contemporary species of Pelycodus in being smaller and generally having lesswell developed hypocon es and mesostyles. Differ from species of Notharctus in lacking symphysealfusion . Differ from species of Smilodectes in having less compressed lower premolars and moredistinct paraconids on the lower molars.


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EARLY EOCENE ADAPIDAE 267Etymology.- Named for Edward Drinker Cope, who originally described the type species exactlya century ago. Suffix lemur refers t o the lemuriform affinities of this genus among archaic primates.Discussion.- The species of Copelemur have long been confused with species of Pelycodus andNotharctus, to which they are closely related. Matthew (191 5, p. 441) recognized tha t the speciesPelycodus tutus, here placed in Copelemur, differed markedly from other species of Pelycodusin the placement of the entoconid on the lower molars and its connection to the metaconid via aprom inent crest. In his original description of praetutus, Gazin (1962, p. 28) referred it and C.tutus questionably to the genus Pelycodus, and suggested that they might represent a distinct genus.He refrained from placing C. praetutus and C. tutus in a new genus because species of Pelycodus andNotharctus sometimes approach them in the distinctive construction of the entoconid corner of thetooth. Pelycodus and Notharctus do not show the entoconid notch and metaconid-entoconid crestdeveloped to the degree seen in the species here placed in Copelemur. The best evidence that a dis-

tinc t clade is represented by the species here placed in Copelemur is their separation as a distinctivesmaller lineage evolving in parallel with Pelycodus abditus and P. fmgivoms in the late Wasatchianof the Big Horn and Wind River Basins (text-fig. 10).As indicated by text-fig. 10 also, Copelemur is abundant in the Big Horn Basin for only a shorttime, represented by a relatively small interval of th e Lost Cabin beds. It is rare bo th before andafter this interval in the Big Horn Basin, although it apparently lived for a somewhat longer periodin the Wind River Basin. Two lineages of Copelemur, one of Pelycodus jarrovii sized animals andthe other smaller, are present in the San Juan Basin in strata equivalent to the Lost Cabin beds (text-fig. 5 , suggesting that possibly Copelemur was a more tropical form than Pelycodus. The availableevidence indicates that Copelemur was relatively more common and more diversified in southernfaunas within N orth America.Copelem ur praetutus (Gazin, 1962)

Pelycodus praetutus Gazin, 1962, p. 28 PI. 4 fig. 2-4.Type.- USNM 22262, a right mandibular ramus with broken P 3 , broken P4 nd M 1 rom 1%miles south of Bitter C reek Station, Sweetwater Co unty , Wyoming.Diagnosis.- Smallest species of Copelemur. Differs from C feretutus, C. consortutus, and C. tutus

also in having relatively narrower molars.Age and Distribution.- Gazin (1962) states that the type specimen comes from strata correlativewith the lowest Wasatchian Sand Coulee beds, however the presence of Pelycodus trigonodusfrom the same locality indicates th at the age is probably mid-W asatchian and equivalent to theupper Gray Bull. Copelem ur praetutus is known with certainty only from the type locality. Twospecimens from Yale Locality 365 (U. Gray Bull beds) in the Big Horn Basin are very close to C.praetutus in size (text-fig. lo ), bu t they do not have the very deep entoconid notch seen in the type.These two specimens possibly indicate an extension of the range of praetutus to the Big HornBasin but more complete specimens will be required to confirm this.Description.- The type specimen of Copelem ur praetutus shows an unfused mandibular symph y-sis, alveoli for a lower canine, a single-rooted PI nd double-rooted P2 and Pg ith broken P3-4and intact M l P measures 3.4 m m in length and 2.4 mm in width. M I easures 3.8 by 3.0 mm,and M2 measures 4.0 by 3.3. The morphology of the$ teeth is veIy similar t o tha t seen in smallPelycodus except that a deep notch separates the entoconid from the hypoconulid crest on M 1 ndM 2. This entoconid no tch opens the talonid medially. The entoconid itself is connected to the backof the metaconid by a strong crest. The paraconids on M 1 nd M2 are rather anteriorly placed, giv-ing these tw o tee th relatively open trigonids as well. One specimen, YPM 14698, is a left Mg rom


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TEXT-FIG. Typ e and referred specimen of Copelemurferetutus in (A) occlusal and (B) lateral view. ACM 4326(type) i s a right M I , ACM 1123 1 is a right M2, both from Lysite beds in the Wind River Basin.

Bitter C reek Station allocated t o this species by Gazin (1962). It measures 5.4 mm in length, 3.4 mmin width, and has a relatively closed trigonid with the reduced paraconid apparently joined to thefron t of the metaconid. The heel of Mg is narrow and curved.Discussion.- The upper den tition of this species is unknown, and th e variation in morphology ofthe lower cheek tee th is inadequately know n. A thoroug h new study of the Bitter Creek Stationdistrict is in progress by Savage, Waters, and Hutchison (1972) th at should greatly increase our und er-standing of the morphology and stratigraphic distribution of Copelemur praetutus.Typodigin-- USNM 22 26 2 (type ), YPM 14697, and YPM 14698.Copelemur feretutus new species

Pelycodus cf. fmgivorus Kelley and Wood, 195 4, p . 344, fig. 4e.Pelycodus fmgivoms ( in part ) , Gu thrie, 1967 , p. 21.

Type.- ACM 43 26 , an isolated right M1 from the Lysite member, Wind River Fo rmation, WindRiver Basin, Wyoming.Diagnosis.- Differs from C. praetutus and C. consortutus in being significantly larger, and fromC. tutus in being significantly smaller. Differs from C praetutus in having relatively broader molars,with the paraconid more closely approximated to the metaconid on MI and M2. Differs from C.consortutus and C. tutus in having less well developed hypocones and mesostyles on the uppermolars.Etymology.- fero L. to carry or bear, in reference to the probable role of this species in theline leading to C. tutus.Age and Distribution.- upper Wasatchian faunal interval, Lysite beds and equivalent, WindRiver and Big Horn Basins, northweste rn Wyoming.Description.- There are no mandibles of this species preserving the anterior den titio n. M1 ispreserved in two specimens, ACM 4326 (type) and PU 18166. In the typ e, M1 measures 4.2 mm in


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EARLY EOCENE ADAPIDAE 269TABLE 6 Summary of measurements of the lower and upper cheek teeth of Copelemur feretutus from the type

locality, Lysite member, Wind River Basin, Wyoming. Measurements in mm. Abbreviations as n Table 1.

length and 3.6 mm in width. MI has an open trigonid, bu t in M2 and M3 , the paraconid is closelyapproximated t o the m etaconid to form a closed trigonid. In M 1 nd M2 text-fig. 8) there is usuallya distinct entoc onid n otch separating the entoconid from the hypoconulid. M3 has a small roundedheel on the talonid like that n C praetutus.

Two maxillae, ACM 432 5 and PU 18 36 5, preserve upp er The former has a moderatemesostyle crest on the upper molars but it is much weaker on molars of the latter. The hypoconeappears to have been weakly developed in both. The upper molars d o no t differ greatly from thoseof early Pelycodus.

Measurements of the upper and lower dentition of Copelemur feretutus are given in Table 6.Discussion.- The specimens from Lysite beds referred to Pelycodus frugivorus by Kelley andWood 1954) and by Guthrie 1967 ) all appear to belong to Copelemur feretutus. A histogram show-ing the relationship of these specimens to the contemporary Pelycodus abditus from the Lysiteis shown in tex t-fig. 5.Typodigm- The following specimens come from the Lysite member of the Wind River Forma-tion, Wind River Basin, Wyoming: ACM 241 6,2 50 9,2 51 0, 25 11 ,28 21 ,29 25 ,43 22 ,43 25 ,43 26

type), 11173 ,11231; PU 176 91,18166 ,18365.In addition, there are a small number of specimens from upper Lysite equivalent beds in the BigHorn Basin tha t belong to th is species. These include YP 186 69,2 325 8, and 30393.Copelemur consortutus new species

Pely codu s frugivorus in part), Matthew, 1915, p. 439, fig. 1I .Notharctu s nunienus in part), Guthrie, 1971, p. 63-


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P. D. GINGER ICH and .E. L. SIMONS

TEXT-FIG. 9 Type specimen of Copelemur consortutus PU 1 8 2 8 2 a left mandible with in A) occlusaland (B) lateral view.

Type.- PU 18282 , a left mandible collected in 19 31 from Alkali Creek, miles northwest ofArminto, Wyoming.Diagnosis.- Differs from Copelemur feretutus and C. tutus in being smaller. Differs from C.feretutus in tending t o have larger mesostyles on the up per molars. Differs from C. tutus in retainingmo re distinct paraconids on M1 and M 2. Differs from C. praetutus in having relatively broaderlower molars, with the paraconids on M1 and M2 more closely approximated to the metaconids.Etymology.- consors L., brother, sister, or partner, in reference to the close relationship of thisspecies to its sister species Copelemur tutu s.Age and Distribution.- Upper Wasatchian faunal interval, Lost Cabin beds and equivalent,known from New Mexico (San Juan Basin), and northwestern Wyoming (Wind River and Big HornBasins).Description.- The .sample of Copelemur consortutus from the type locality is small, consistingof only five mandibles and an isolated upper to ot h (see Table 7). For this reason much of the follow-ing description will be of a slightly earlier and larger sample of Big Horn Basin specimens from Yale

Localities 1 74 ,19 2, and 193.One specimen, YPM 28178, preserves the front of the mandible, with an unfused symphysis,alveoli for the canine, a single-rooted P I , and double-rooted P2 , and the crowns of P,., and M I .YPM 28196 and 28258 preserve the crowns of P3 4 and MI 3 . P3 has a simple, sharply pointedcrow n without accessory cusps. P4 has a similarly sharp protoconid with a small paraconid and adistinct metaconid. The heel of P4 has a distinct hypocon id and it is extended posteromedially some-what as in C. tutus (AMNH 16205). MI and M2 in most specimens have a deep entoconid notch,


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EARLY EOCENE ADAPIDAE 27 1TABLE 7 Measurements of the lower dentition of opelemur consortutus from the type locality in the Wind

River Basin. Measurements in mm. Abbreviations as in Table 1.

PU 18282 type) 4.0 3.2 4.1 3.5 5.2 3.2PU 20 59 1 3.6 2.6 3.8 3.4 3.9 3.6 5.1PU 20 593 3.6 2.6 4.0 3.4PU 20 59 3 3.9 3.2 4.2 3.7PU 20 59 5 4.1 3.3 4.2 3.6 5.2 3.1

but the typ e specimen and several others e.g., YPM 28 239 ) have this feature less well developed thanmo st. The heel of the talonid on M3 has the narrow round ed shape typical of Copelemur but a fewspecimens show a tendency toward developing a median fissure and twinned hy pocon ulids.The maxillary d entition is best represented by YPM 27 29 2, having p and in almost perfectcondition. This specimen from Yale L ocality 192) has a small mesostyle crest and no trace of ahypocone on the postprotocingulum of M1 and M2. Another specimen from the same locality,YPM 2 97 03 , has small hypoc ones on M1 and M 2 . In most features the upper cheek teeth of Cope-lemur consortutus resemble closely those of early Pelycodus trigonodus.Discussion.-- The size of first lower molars in Copelemur consortutus from Lost Cabin beds inthe Wind River Basin is plotte d in text-fig. 5. Comparing this distribution with specimens from LostCabin equivalent strata in the San Juan Basin, and comparing the specimens from both areas, itappears that the same species is represented. AMNH 162 10 figured by Matthew , 19 15) and AMNH55504 appear especially close to the type of C. consortutus although there are some minor differ-ences in cusp patte rn, especially on the trigonid of M 3.In measuring specimens from the Lost Cabin beds, Guth rie 196 7) confused three species as tw o,and his measurements were thu s incorrect as a result. The distribution of MI size from that intervalis given in text-fig. 5, which clearly shows that there is more variation than can be accommodatedin tw o species. This difference is im po rtant, as it help s to c larify the relationship of Wind River LostCabin deposits to those in the Big Horn Basin compare tex t-fig. 10 here with fig. 7 in Gingerich,197 6a). Strata equivalent t o typical Lost Cabin beds are clearly represented in the Big Horn Basin.Typodigm . Five specimens are know n from the ty pe locality in the Wind River Basin: PU 1828 2type), 2059 1,205 93, and 21759.In addition, the following specimens are known from th e San Juan Basin: AMNH 1 62 10 ,5 55 01 ,555 04, 555 15, 5 55 18, and 555 30. Numerous specimens from the Big Horn Basin are preserved inthe Yale collection, among them YPM 27 29 2,2 81 78 ,28 19 6, 28225, 28235 ,2823 9,28 258 ,282 74,28287,29703.

Copelemur tutus Cope, 1877)P1. 1 , fig. ; text-fig. 6b

Tornitherium tutus Cope, 1877 , p. 141, PI 39, fig. 19.Pelycodus tutus in part), Cope, 1881, p. 187. Cope, 1885, p. 228.


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2 72 P. D. GINGERICH and E. L. SIMONSPelycodus tutus Matthew 1915, p 4 4 1 fig. 15.Pelycodus? tutus Gazin, 1962, p 29.

Type.- Unnumbered right mandible with P3 4 and M , now lost, from the Wasatchian of NewMexico. AMNH 1 62 06 (Pl. I , fig. 3) is a good top oty pe preserving M1 and M2.Diagnosis.- Differs from other species of Copelemur in being significantly larger (see Table 3).Age and Distribution.- The ty pe com es from Almagre or Largo strata , late Wasatchian age, Lost

Cabin beds equivalent, know n only from the San Ju an Basin of New Mexico.Description.- The type specimen of Copelemur tutus was well figured by Cope (1877, P1. 39,fig. 19); it shows clearly th e very deep en toc on id no tc h o n M1 characteristic o f this species and of thegenus. Cope (18 77, p. 142) published th e length and w idth of M1 as well, so th e species is wellestablished even though the ty pe specimen is lost. M1 in th e type m easured 5.0 mm in length and4.5 mm in width.Cope's typ e specimen preserved alveoli for th e lower ca nine, a single-rooted P I , doub le-roote dP 2 , and the crowns of P,, and M I . Three additional mandibles are known, which show that opentrigonids characterize all the lower molars, the paraconids being small and rather anteriorly placed.M1 and M 2 have the very deep entoc onid not ch characteristic of the genus (text-fig. 12). Mg has asimple, narro w, rounded heel on the talonid. Otherwise the lower den tition m ost closely resemblesthat of Pelycodus.

A single upper molar, M1 or M2 (AMNH 55462) is known that has a relatively small hypocone,and a small but distinct mesostyle cusp connected to the ectoloph by a fine crest. A paraconuleis present, but there is no metaconule, and there is no lingual cingulum on this particular tooth.

Discussion.- Copelemur tu tu s the type species of the genus, is a rare but distinctive element inthe W asatchian fauna of the San Juan Basin. Judging from the distribution shown in text-fig. 5 ,it is possible that C. tutus in the Largo replaced Pelycodus jarrovii ecologically, the latter apparentlybeing confm ed t o the Almagre facies.Gazin (1962, p. 29) questioned whether this species really belongs in the genus Pelycodus. It isclearly distinctive and we have placed it in the new genus Copelemur but it is nevertheless mostclosely related to Pelycodus.Typodigm.- AMNH 1 62 05 -16 20 7,5 54 62 . No othe r specimens of this species are know n.

PHYLOGENY AND EVOLUTIONAt t he beginning o f this paper we outlined our approach t o phylogeny reconstruction for groups

of animals th at have a reasonably dense and continu ous fossil record . The first require me nt is asound stratigraphic framework, and it has been provided in th e present case by t he measured strati-graphic sections of Meyer and R adin sky, and Neasham and V ondra. The second requirement is adetailed study of morphological variation within each locality sample his to o has been done, aswas illustrated above in the section of the paper on dental variation in Pelycodus. The final step inorganizing data for stratophenetic analysis is to integrate the distribution of variation seen in eachlocality sample or stratigraphic interval in to t he general stratigraphic framework.The organization of dental size and variation in early Eocene Adapidae from the cen tral Big HornBasin in Wyoming is illustrated in the raw data plotted in text-fig. 10. This data has been furtherint erp ret ed, based on stra top he net ic linking of very similar samples in adjace nt stratigraphic intervals,and it yields the pattern of lineages shown by dashed lines in text-fig. 10. Studied in stratigraphiccontext, it is clear that a single lineage o Pelycodus was present in the Big Horn Basin through m ostof th e Wasatchian, bu t tw o lineages are present in Lost Cabin beds. Furth erm ore, a distinct lineageof Copelemur is present in both Lysite and Lost Cabin beds in the Big Horn Basin (and possibly inupp er G ray B ull beds as well).


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EARLY EOCENE ADAPIDAE 273Given the p attern of phy logeny in text-fig. 10 , and the details of morphological change discussedin the section of this paper on systematics, it is possible to subdivide each lineage into a sequence of

valid species. Pelycodus ralstoni evolved into P. mckennai which evolved into P. trigonodus and SOfo rth . While the d istinction between lineages is nonarb itrary, it must be em phasized tha t the exactboundary between successive species with in a lineage is arbitrary (although each species as a wholecan be distinguished morphologically). No na tural breaks are obvious, and it is necessary for ease ofdiscussion and for use in b iostratigraphy to make essentially artificial boundaries between species.It turns out, largely for historical reasons, that these correspond fairly well with established subdivi-sions of the W asatchian (Sand Coulee, lower Gray Bull, etc. which themselves are poorly defined atpresent). Since the boundaries between time successive species must be time-parallel to make taxo-nomic diversity reflect biological diversity, the successive species of Pelycodus can potentially serveas a useful substitute in zonation of th e W asatchian, pending a full scale faunal study of this intervalof evolutionary history. In this connection it is imp ortant t o emphasize tha t the distinctions betweenspecies are based on comparisons of whole samples from each locality, and the transitions betweenspecies appear in every case t o be continuous and gradual. Thus any zonation based on Pelycoduscould be used, at best, t o subdivide the W asatchian in to five subunits.Our primary interest in studying Pelycodus and Copelemur has not been biostratigraphic zonationof the Wasatchian, but rather the patterns of phylogeny and evolution exhibited by these genera.The genealogical relationships of the species of Copelemur are still somewhat obscure, owing to theinadequate stratigraphic record of these species. The only reasonably certain relationship is theancestor-descendant relationship of C eretutus and C consortutus. Within Pelycodus on the otherhan d, we can be m uch more certain about genealogical relationships. The four species from P.ralstoni to P. abditus appear to be a single ancestor-descendant sequence, with P. abditus giving riseto both P. frugivoms and P. jarrovii.As we discussed in the introductory sections of this paper, body size is an important componentof an animal's ada ptation, and too th size provides an important basis for studying relative bod y size.The patter n of change seen in tooth size (and, by inference, in body size) is shown in text-figs. 10 and11. The major lineage of Pelycodus became progressively larger through t he course of th e Wasat-chian, except for P. frugivoms which became smaller. The one lineage of Copelemur documentedin text-fig. 10 also became smaller. Pelycodus fmgivom s and P. jarrovii apparently exhibit some kindof ch aracter divergence in geological time, although this has not yet been fully stud ied.For comparison, one of us P. D. G.) has initiated a new collecting program in Wasatchian sedi-ments of the northern Big Horn Basin (Sand Coulee area) where fossils are abundantly preserved ina well exposed sequence of sediments spanning the Sand Coulee through upp er Gray Bullfaunal subdivisions. In two seasons to date more th an 2 00 mandibles and maxillae of Pelycodushave been collected, although section measuring is still in progress and only 35 of these can yet beplo tted stratigraphically. These are plo tted in text-fig. 1 1 on a vertical scale adjusted to be compara-ble to tha t in text-fig. 1 0. Even given the small number of samples available to date , it is clear thatthe same pattern of Pelycodus ralstoni evolving i nto P. mckennai which in turn becomes P. trigonodusis shown here as was shown in the central Big Horn Basin. Obviously, an impo rtan t future step willbe to study Pelycodus in southern Wyoming, Colorado, or New Mexico in a similar way to see if theevolutionary pattern s seen there are the same. The fact that several species, such as P. fmgivoiusand P. jarrovii are found in both New Mexico and Wyoming strongly suggests that similar phyloge-netic patte rns will be fou nd in b oth areas, but it is nevertheless of great importance t o test this.In addition to evolutionary change in tooth size and body size, one can study the patterns ofchange in other characters of Pelycodus and Copelemur as well. n attem pt has been made in text-fig. 2 to quantify the acquisition of a mesostyle and hypocone in Pelycodus. This clearly happenedgradually, the earliest samples of P. ralstoni from S and Coulee beds having neithe r cusp. Mesostylecrests appear in various stages of development in Pelycodus with larger specimens (both within


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74 P. D. GINGERICH and E. L. SIMONSpopulation samples and com paring successive popu lations having stronger mesostyle crests. Finally,bo th th e large and small Lost Cabin species of Pelyc odus have large Notharctus-like mesostyle cusps.The development of the hypocone shows the same pattern, but its development is retarded with re-spect t o the evolution of the mesostyle. Hence the upper G ray Bull species P. trigonodus tends t ohave a distinct mesostyle crest but no hypocone, an interesting example of the mosaic pattern ofevolu tion of morphological characteristics. Schoeninger 1976) studied the functional significance ofthe evolution of a mesostyle in Pelycodus and in the living Alouatta and concluded that the mesostyle

WlNDLOST RIVERCABIN

Notharctus I--- -4I

vii- I - - - - - - - - - - -I

/

WlND RIVER LYSITE P abditus //

/ I7/ /

I,ISTRATIGRAPHIC RECORD OF/ - 2

/I EARLY EOCENE ADAPIDAE

7I mckenna BIG HORN BASIN, WYOMING/

I? ralstoni /

TEXT-FIG. 10 Stratigraphic distribution of Pelycodus and Copelemur in the Big Horn Basin, Wyoming, basedon collections in the Yale Peabody Museum and the Museum of Paleontology, University ofMichigan. Solid lines show sample range, vertical slash is mean, bar is standard error of mean,and small numerals are sample sue. Vertical axis is measured stratigraphic section in feet)spanning most of Wasatchian, dated at approximately 5 3 my to 49 my before present, basedon Gingerich 1976a, fig. 2 . Oblique dashed lines show pattern of phylogenetic relationshipsinferred from data. Horizontal dashed lines with open bars show important samples of Pely-codus and Copelemur not in measured sections, from: Sand Coulee area P. ralstoni), centralBig Horn Basin P. trigonodus), Wind River Lysite beds C. feretutus and P. abditus), and WindRiver Lost Cabin beds C. conso rtutus , P. frugivorus, and P. jarrovii). Asterisks mark typodigmof valid named species. Pattern for Pelycodus modified slightly from Gingerich 1976a, fig. 7by addition of new samples and reanalysis of Lost Cabin samples. Note close relationship ofP arrovii to sample of Notkarctus from Carter Mountain in the Big Horn Basin. Note also theseparate evolutionary identity of Copelemur in the Big Horn Basin.


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EARL Y EOCENE ADAPIDAE 275functions to puncture leaves during the initial stage of their mastication, but no comparable studyhas been made of the functional significance of the hypocone in Pelycodus (or in Alouatta . Theevolution of the upper molar dentition in the sequence from Pelycodus ralstoni t o P. jarrovii is illus-trated in text-fig. 13. Only five stages of evolution are represented, but they illustrate the generaltrend toward increased size, larger mesostyles, and larger hypocones in this lineage of Pelycodus.

As a final point we should consider the relationship of early Eoce ne Adapidae to their middleEocene descendants. As text-fig. 1 0 and l l other evidence suggests, Notharctus is a direct descend-ant of Pelycodus jarrovii. The species of Notharctus presen t in th e Bridger or Gardnerbutteaninterval of th e m iddle Eocene (McGrew and Sullivan, 19 70 ; Rob inson , 19 66) is significantly largerthan P. jarrovii bu t otherwise practically indistinguishable. The origin of Smilodectes, however, isa more difficult and still unsolved problem. Smilodectes could be derived from either Pelycodusfmgivoms, or from P. jarrovii. The latter possibility seems more likely, b ut further detailed strati-graphic and morphological study will be required to confirm this.

ACKNOWLEDGMENTSWe th an k Drs. W. P. Coom bs, Prat t Museum o f Amherst College; M. C. McK enna, Am erican

Museum of Natural History; Donald Baird, Princeton University; Peter Robinson and Judith Van

SAND COULEE AREA PELY ODUS/ /

7 m / // - - - - 7;/ I? trigonodus /

/ - /600 /

/ -3 /// /

/ /500 // /

// /

/ /400 P mckennai ///

/ 4 b U M LOCALITY SC-133300 // /

/ - 2 // /

t? ro lstoni /-200 // 5 l / // / - - - - 2

/

TEXT-FIG. 11 - Stratigraphic distribution of Pelycodus in the Sa nd Coulee area of the no r thern Big Horn Basin,Wyoming. Vertical scale (in meters) adjusted to match rate of evolutionary change in text-fig. 10. Symbols and type samples of P. ralstoni and P rigonodus same as text-fig. 10. Allspecimens in the Museum of Paleonto logy, University of Michigan.

Couvering, University of Co lorado Museum; R. J. Emry and C. L. Gazin , National M useum of NaturalHistory ; D. E. Savage, University of California, Berkeley; and P. 0 McGrew, University of Wyoming,fo r permission t o study and , in some cases, borrow specimens in their care. In addition, discussionof Pelycodus phylogeny with Dr. T. M. Bown, Dr. M. C. McKenna, Mr. Earl Manning, Mr. K. D.Rose, and others ha s been very helpful.


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276 P D. GINGERICH AND E. L. SIMONSMESOSTYLE

.I400copelemur ,so C

1200 :0

elycodus1000

HYPO ONE1

ENTO ONID NOT Hf O

TEXT-FIG. 1 2 Pattern of evolutionary change in the mesostyle, hypoco ne, and entoconid notch in Pelycodusand Copelemur from the Big H orn Basin, based o n collections in the Yale Peab ody Museum.Fully developed features are shown by arrow s in inset figures. Each character was scored on ascale from 0 to 2 depending on w hether it was absent, present, or strongly developed. Verticalaxis same as in text-fig. 10 Solid circles and lines show pattern of change in mean values forPelycodus. Open circles and dashed lines show pattern of change in mean values for Copelemur.Note that evolution of a mesostyle preceded evolution of a hypocone in Pelycodus. Note alsofailure to establish an entoconid notch in Pelycodus while it characterizes specimens of Cope-lemur.

Text-figures 4 and 7 were drawn by Ms. Krystyna Swirydczuk, the pho tographs in Plate 1 are byMs. Karna Steelquist, specimens were prepared for study by Mr. R. G . Habetler, and t he m anuscriptwas typed by Mrs. Gladys Newton, all at the University of Michigan. This research was supportedby a Faculty Research Grant from the Rackham School of Graduate Studies, University of Michigan.

Opposite page)TEXT-FIG. 3 Evolution o f upper molars in th e lineage from Pelycodu s ralstoni to Pely codu s jarrovii all drawnto same scale. No te increasing size, enlarging mesostyle, and enlarging hyp oco ne as docu me ntedin text-figs. 10 and 12. All figures except B) from Matthew 1915), slightly mo re tha n twice

natur al size.


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E RLY EOCENE D PID E

0 /4637A 4

F jarrovii

t trigonodus

N o 67 13 tt mckennai

Evolution of Upper Molarsin Early Eocene PelycodusP ralstoni


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P. D. GINGERICH and E. L. SIMONSLITERATURE CITED

BADER, R. S. 1965 . Heritabili ty of dental characters in the house mouse. Evolution, 19 : 378-384.BOWN, T. M. 1976 . Affinities of Teilkardina Primates, Omomyidae) with description of a new species fromNo rth America. F olia Primatol. , 25 62-72.CLEM ENS, W. A. 19 74 . Purgatorius an early paromomyid primate Mammalia). Science, 184 : 903-905.COPE, E. D. 1874 . Rep ort u po n vertebrate fossils discovered in New M exico, with descriptions of new species.Annual Report of the Chief of Engineers, U. S. Army, Appendix FF , p. 589-606 Separatum p. 1-18).875. Systematic catalogue of Vertebrata of the Eocene of New Mexico, collected in 187 4. R epor t to theEngineer Dept., U . S. Arm y, Washington, p. 5-37.87 7. Report upon the extinct Vertebrata obtained in New Mexico by parties of the expedition of 1 874.Chap ter XII, Fossils of the Eocen e period. Geographical Surveys West of One Hun dredth M eridian, G. M.Wheeler, Corps of Engineers, U. S. Army, W ashington, 4: 37-282.881. On t he Ve rtebrata of th e Wind River Eoce ne beds of Wyoming. Bull. U. S. Geol. Geog. Surv. Terr.,6 : 183-202.

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Adapidae in N. America Gingerich

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