a e ‘ ~ \ ~) HARVARD UNIVERSITY ish LIBRARY OF THE Museum of Comparative Zoology ostilla i YALE PEABODY MUSEUM oF NAaTuRAL History Number 54 October 30, 1961 New Haven, Conn. THE DENTITION OF OURAYIA: —ITS BEARING ON RELATIONSHIPS OF OMOMYID PROSIMIANS Eiwyn L. Smrons Gazin (1958) has established for the North American anaptomorph, or so-called ‘ttarsioid” prosimian Primates two families: the Anaptomorphidae, containing seven early and middle Eocene genera; and the Omomyidae, to which eleven Eocene and one early Oligocene genera are assigned by him. It has long been recognized that members of these two families differ distinctly from the more clearly lJemur-like North American prosimians of the subfamily Notharctidae, which has been suggested, originally by Leidy (1873:90) and more recently by W. K. Gregory (1921:220), as being plausibly the group from which the South American platyrrhine Primates arose. Recently, however, the candidacy of Notharctus and its allies for such an ancestral position has been increasingly questioned. This is because, although generalized in many ways, notharctids already show a number of features that are unlike Platyrrhini. The greater expression of the hypocone and mesostyle, together with a tendency toward doubling of the outer cusp of the fourth upper premolar all non-platyr- thine features, but seen in the successively later species of Notharctus—indicate a dental pattern that was diverging from, and not approximating that which typifies the Platyr- 2 Postilla Yale Peabody Museum No. 54 rhini. Moreover, both Notharctus and Smilodectes exhibit up- per third molars that, relative to the other cheek teeth, are much larger and more complex than those of the earliest known notharctine, Pelycodus, as well as of those of Oligocene-Recent South American Monkeys. Some current students regard omomyid prosimians as al- ternative, or better, candidates for the ancestry of Ceboidea ; for instance, see Gazin (1958:100). This idea appears to have had its origin in comments by J. L. Wortman (1904:242) in his imaginative but often overlooked studies on Eocene Pri- mates at the Yale Peabody Museum. Probably the main reason the case for a possible ancestor-descendant relationship be- tween omomyids and ceboids has not previously been considered in detail is that no really complete dentitions of members of this prosimian family have been described. Without better knowledge of the anterior dentition most of those acquainted with the problem appear to have hesitated in expressing opin- ions as to the phyletic relationships of this group. The com- pleteness of the dentition in one omomyid, a specimen of Ourayia uintensis, described below, largely obviates this diffi- culty. ACKNOWLEDGMENTS The writer is greatly indebted to Dr. Glenn L. Jepsen of the Department of Geology, Princeton University, who gener- ously made available for study and description here the unequalled specimens of Ourayia in his charge collected for Princeton by J. B. Hatcher, O. A. Peterson [both formerly associated with the Yale Peabody Museum], and by later field expeditions of Princeton University. Thanks are also due Dr. M. C. McKenna of the American Museum of Natural History for making available for study the type specimen of Ourayia uintensis (Osborn) and to Dr. C. L. Gazin of the U.S. National Museum for kindly discussing with me some problems relating to the Omomyidae. Figures were prepared by Margaret EK. Freeman of New Haven and the early com- pletion of this paper was facilitated by a grant from the Wenner-Gren Foundation for Anthropological Research of New York. Oct. 30, 1961 The Dentition of Ourayia 3 ABBREVIATIONS A.M.N.H.. American Museum of Natural History, New York. CRIN Bes tre. Sayre ares _... Carnegie Museum, Pittsburgh. Raw... Princeton University, Princeton Were. Yale Peabody Museum, New Haven DESCRIPTION AND RELATIONSHIPS OF OURAYIA The single species of this genus, Ourayia uintensis, 1s ap- parently retricted to Uinta (B) horizon of the late Kocene. It was originally described by Osborn (1895:77) as a species of Microsyops. Later, Osborn recognized that the assignment of this species to Microsyops was in error, remarking (1902 :202): “Its nearer reference is either to the Anapto- morphidae or to some member of the Notharctidae.” A further, but incomplete, step in the direction of a more correct taxo- nomic assignment for this prosimian species was made by Wortman (1904:232) who referred it to the genus Omomys. However, it remained for Gazin (1958:70) to recognize that this species belongs to a distinct omomyid genus for which he coined the name Ourayia, after the village of Ouray to the north of the “White River pocket,” Utah, from which it seems most, if not all, known specimens of this species have been vecovered. Gazin (1958) noted that this genus is close to later Socene omomyids such as Washakius, Hemiacodon, and Stockia and pointed out that the species differs greatly from any assigned to Notharctus which it resembles only in its comparatively large size. The specimens from the Princeton collections, described here, are much more complete than the American Museum materials available to Gazin and further serve to emphasize the distinctness of the dentition of Ourayia from that of any notharctid. In view of the completeness of the specimen P.U. 16431 it is now possible to define much more adequately the structure and relationships of this primi- tive prosimian. ‘b Postilla Yale Peabody Museum No. 54 Order PRIMATES Linnaeus 1758 Suborder PROSIMIT [lliger 1811 ? Infraorder LEMuURIFORMES Gregory 1915 Family Omomyidae Gazin 1958 Subfamily Omomyinae Wortman 1904 OURAYIA Gazin, 1958 Type species: Ourayia uintensis (Osborn), 1895. Included species: Ourayia uintensis. Distribution: Late Eocene, Uintan stage; White River pocket, Uinta Basin, Uintah County, Utah. Generic distinctions: In addition too having lower and more anteropos- teriorly elongated trigonids and comparatively larger talonid basins than in Hemiacodon, as mentioned by Gazin (1958-71) for Ourayia, the hy- poconid is less anteroposteriorly conpressed than in Hemiacodon and does not project as far laterally from the main body of M, as it does in Stockia and Hemiacodon. M,.. hypoconulids are not distinctly set off as in Hemi- acodon and Washakius. Resembles HTemiacodon and differs from Washakius in lacking molar metastylids. In Ourayia the apices of molar paraconids are situated somewhat more internally than in Sfockia and M, hypoconulids are comparatively smaller than in /Zemiacodon and Washakius. Second and third molars above and below are larger compared to first molars than in Washakius and Hemiacodon. Ourayia agrees with species of these two gen- era in having crenulate tooth surfaces, but unlike Washakius has only a single metaconule. Differs from Hemiacodon in having a much less sharply broken crest between para- and metacones and no appreciable development of P* parastylar cuspule. Anterolingual cingular region of M'* shows a pericone variably present as is the case also in Hemiacodon and Omomys among omomyids and in the living platyrrhine Samiri sciurea. Discussion: One difference between Ourayia and Hemiaco- don, noted by Gazin (1958:71), that the My paraconid of the former is nearly obscured in the anterior trigonid crest, is now seen to be a feature of the type specimen alone. The M, para- conid on both sides in P.U. 11236 and P.U. 16431 shows dis- tinctly. This difference, together with slightly smaller size and less oval My outline in the latter two specimens might suggest a species distinction for the Princeton materials were they not from the same horizon and area as the type. Gazin pointed out that the lower dentition of this primate does not resemble Notharctus. This conclusion is amply confirmed in the upper dentition of Ourayia where, apart from basic differences in cheek tooth crown patterns, the upper incisors are seen to be Oct. 30, 1961 The Dentition of Ourayia 5 comparatively huge and the canine much reduced. hese fea- tures, together with the loss of P-, are in marked contrast to the situation in notharctines which have small upper incisors and long canines. The difference here is of the same order of magnitude as that separating Malagasy lemur from loris dental patterns and amply justifies reference of Ourayia and Notharctus to different families. As regards the phyletic position of Ourayia among omo- myids I suspect that the genus may have been derived directly from Hemiacodon, particularly since the Ms paraconid is not as unlike that of Hemiacodon as was supposed from the type specimen alone. Possible relationships with the early Oligocene Macrotarsius montanus are less certain, but direct derivation of this species from Ourayia is not out of the question. Crenulations of the enamel resembling those of both Hemiacodon and Ourayia, although less pronounced, are evident in the talonid basins of the Oligocene form. Paraconids are situated slightly more laterally than in species of the latter two genera, but this difference need not rule out a close relationship between them and Macrotarsius. Present knowledge of the relative size, num- ber and positioning of the anterior lower teeth in several omo- myid genera, Omomys, Washakius, Chlororhysis, Hemiacodon, and Ourayia strongly suggests that Clark (1941:562) was correct in interpreting the lower dental formula in this Oh- gocene omomyid as 2.1.3.3, the typical formula for the group. If P, is lost and Ps single-rooted as in other Omomyidae, then the small anteriormost remaining tooth in Macrotarsius must be the base of a reduced canine (see fig. 1). This canine, how- ever, is not less prominent than in any other omomyid as Clark suggested, although the lateral incisors do appear to reach an extreme of reduction, judging from the alveolus. In Oura- yia, moreover, the lower incisors are more procumbent. To the extent that the species of Hemiacodon, Ourayia, and Macrotarsius are in, or close to, a single progressing phylum, the suggested trends, apart from size increase, were toward deepening and shortening of the ramus mandibuli, together with a size reduction and more vertical implacement of the lower incisors. Perhaps the latter changes are to be correlated 6 Postilla Yale Peabody Museum No. 54 with increasing use of the hands in feeding and with facial foreshortening. OURAYIA UINTENSIS (Osborn), 1895 Figures 1, 2, 3. Microsyops uintensis Osborn 1895, Bull. Amer. Mus. Nat. Hist. No. 7, pp. (Us kes Ie Omomys uintensis Wortman 1904, Amer. Jour. Sci. 4th Ser., Vol. 17, pp. 134, 135. Ourayia uintensis Gazin, 1958, Smithsonian Mise. Coll. Vol. 136, No. 1, pp. 70-72, pl. 13, fig. 8. Type of genotypic species: A.M.N.H. No. 1899; left mandibular ramus with P,-M.. Type locality: Late Eocene, Uinta (B), White River, Utah. Hyopdigm: Type and A.M.N.H. 1900, mandibular fragment with right M,; P.U. 11236, left and right mandibular rami with left P,;-M, (lacking trigonid of M., alveoli of P.; right P,-M, (trigon of M, missing), alveoli of I,-P,; P.U. 11288, edentulous right mandibular ramus; P.U. 16431, max- illae with upper dentition excepting left P*, mandibular fragments with left I,, P;-,, damaged M,, M.-M;; right I,, damaged P,, M,-M., trigonid of M3. Horizon and locality: Lower Uinta [B], upper Eocene, White River Pocket, Utah. P.U. 16413, Section 2, T. 9 S., R. 20 EK. Uintah County, Utah; P.U. 11236, 11288 Uinta [B], Kennedy’s Hole, White River, Utah. Specific diagnosis and description:! A moderate sized prosimian; com- parable parts approximately within the size range of the living Perodicticus potto. Dental formula 2.1.3.3; I, spatulate, and somewhat procumbent, 2.1.3.3 posteriorly with median vertical ridge and basal cingulum rising internally halfway toward crown; I, smaller than I, (alveolus) ; c probably smaller than I, (root), no diastema; P. single-rooted; P, with internal cingulum lacking on P,; P;-, of equal height, paraconid, metaconid, and external cin- gulum present in P,, -lacking in P,, heel of P;., with single cusp situated laterally. Surfaces of cheek teeth, particularly, bearing wrinkled or crenu- late patterns. M. slightly larger and more oval in outline than M,. Molar paraconids distinct (except in M, of type), situated only slightly less laterally than metaconids and connected with protoconids by an arcuate crest. Hypoconulids not sharply set off on M,... M; hypoconulid not as ‘T fail to grasp fully the logic behind the increasingly popular practice of neglecting to distinguish between generic and specific diagnoses in treatments of monospecific genera. Generic characters, in this case, are those features which prevent reference of such species to other genera; the specific, those attributes which, combined, characterize a given, and no other, species. The two suites of features are not indistinguishable, although I suspect that the failure to see that they are not may be one prime contributor to the production of unnecessary or invalid genera. Oct. 30, 1961 The Dentition of Ourayia 7 large as in most earlier omomyids. Upper incisors large, I>* sub-equal in size, spatulate; upper canine reduced, premolariform, smaller than P?; P? small, lacking lingual cusp; P** with s‘ngle inner and outer cusps. M'* with para- and metaconules, varying expression of cuspules on lingual pro- tocone cingulum in positions of hypocone and pericone, pronounced labial cingula with cuspule not seen in Hemiacodon in position of mesostyle. Discussion: Ourayia uintensis is of greater size than are other known omomyids except for the considerably younger species Macrotarsius montanus of Chadronian age, which is about ten percent larger in comparable parts. Among omo- myids earlier or contemporary with Owrayia, Hemiacodon gracilis most nearly rivals it in size, being about eighty-five percent as large in most measurements. The remote possibility that canines were lost in O. wintensis and that there were actually four premolars above and below in this species has been considered but rejected. In spite of its premolariform appearance, the upper canine apex is directed forward while that of P® has a distinct backward tilt which can hardly be due to crushing. Moreover, occlusion of the teeth in P.U. 16431 shows that the lower canine (which has a larger root than the teeth adjacent to it) lies in front of the upper canine, as would be expected. The maxillae of P.U. 16431 are crushed, but some features of interest are still to be observed (see fig. 2). Much of the premaxilla of the right side is preserved, and a wavy suture just in front of the canine and arching backward is indicated on both sides. Both narial margins of the premaxillae are evident anteriorly. The thin, fairly long right nasal has drop- ped down between the premaxillae. In the orbital region the jugal is missing and the orbital border of the right maxilla much eroded, so that it is not possible to determine whether the malar contacted the lachrymal. However, it is difficult to avoid the conclusion that the orbit was quite large relative to the size of the rostrum. This possibility is also indicated by a specimen of Hemiacodon figured by Gazin (1958: pl. 4, fig. 4) in which the supraorbital border of both orbits is preserved. Since this specimen and P.U. 16431 are the only individuals of any species of omomyid primate which preserve part of the skull other than mavxillae or dentaries, they deserve special comment. It appears that in Ourayia the depth of the rostrum 8 Postilla Yale Peabody Museum No. 54 above the canine was greater than the horizontal distance from the narial to orbital borders, so that this primate shows the progressive feature of being comparatively short snouted, evidently much more so than in Smilodectes or Notharctus. On the other hand, this “advanced” omomyid feature is balanced by the presence of a metopic suture between the frontals in Hemiacodon figured by Gazin as is generally the case in “‘primitive” or non-tarsioid prosimians. The reduced upper canine of O. uintensis, taken together with possession of a lower canine root that is hardly larger than P. in cross-sectional area, indicates a small, premolari- form lower canine. Both Matthew and Granger (1915: fig. 24) and Gazin (1958: pl. 8) illustrated specimens of the closely related Hemiacodon gracilis which preserve broken lower canines that are indeterminate as to the height of this tooth. A specimen of H. gracilis recently located in the Yale collec- tions, Y.P.M. 16253 from Henry’s Fork, Wyoming, shows that the entire tooth was extremely premolariform and only barely higher than Ps (see fig. 1). In view of an overall simi- larity in general size and proportions of the other teeth between O. wintensis and H. gracilis, the reduced upper canine of the former almost certainly opposed a premolariform tooth below. In earlier omomyids, Omomys and Chlororhysis, the lower canine is relatively larger (fig 1). Such canine reduction in the later omomyids practically eliminates them from con- sideration as being ancestors of any Ceboidea. Although O. wintensis may be derived from H. gracilis, ref- erence of the former species to the genus Hemiacodon seems out of the question. The primary distinctions between these two genera have been cited in the diagnosis given above (page 4), and they are considerably greater than those which have been proposed as separating the genera Omomys, Loveina, and Chlororhysis. No doubt, known omomyid species could be lumped under fewer genera, but in the fragmentary state of present knowledge concerning them, limited almost entirely to dentitions, this would serve no useful purpose and in any event cannot be attempted here. Curiously, wear on M— of O. wintensis, P.U. 16431, is dis- tinctly less than on M-.. That this could be due to misinter- Oct. 30, 1961 The Dentition of Ourayta 7) pretation of the dental formula, with molariform P——and loss of one of the molars seems impossible, particularly because in the closely related H. gracilis the normal sequence of molar wear can be established for numerous specimens. MEASUREMENTS IN MILLIMETERS OF OURAYIA UINTENSIS Length I.— My, Length P.,—M, Length P., — M. Depth of jaw below M, Transverse diameters: Anteroposterior diameters: LOWER DENTITION P.U: Jeae No. No. 16431 11236 eee ee 27.6 eS 8.0 18.8 13.0 14.6 6.2 6.8 ee ee 2.0 1.9 Tt tie, Arerperes CAS ae aE: : Pipers: Ole oe. LAG eran [Day epee ie 2.0 2.3 it ew eee Zui 2d M, (trigonid) 3.0 2.8 Misne fete 2 i eae enol Pel IVI ee ees ree 2.9 3.0 M, (talonid) 3.5 3.3 M; 3.6 3.3 M., 3.2 3.0 | Ep ee at 2.3 2.1 ie eye ; Ps 1 Si(Ga) ee Pe 2.9 3.1 P, “aed | 3.7 M, 4.0 4.2 M. 4.2 4.2 IVER tee 9: 5.2 4.6 2.3 2.6 2.9 3.4 3.6 3.8 10 Postilla Yale Peabody Museum No. 54 UPPER DENTITION P.U No. 16431 Wenig ile Ne ——— Ne a Sgn ees 28.9 Bengt hee ANE eee oe eee ies Transverse diameters: I? ......... V3 | opie herent ir Coe 1.4 | at ae eS ae 1.4 | PEED eae oe ok Pee Oe aie 3.8 1 (oo 4.8 1 Cee ead 5.2 M? 4.8 Anteroposterior diameters: een 5 eels. 3.4 iy els Roe. Sal Gi Sk hey eae Rees Saran De Pe eo Be en Sell Ps geese. 3.0 Mea eer. oe 3.8 Mies Seay eee 4.1 1, Geo 3.8 Measurements for a possibly associated right P, of P.U. 16431 have been given above. Although there is no definite contact between this tooth and the right mandibular fragment, it is the proper size and shape for an omomyid P,, judging from morphology of Ps in Omomys and Hemiacodon. RELATIONSHIPS OF THE OMOMYIDAE The hypothesis that omomyid prosimians may be near the ancestry of the platyrrhine monkeys is based on several points of direct and indirect evidence, most of which are rather Oct. 30, 1961 The Dentition of Ourayia aU | equivocal, as is often the case with such phyletic conjec- tures. For those who do not favor a notharctid derivation for platyrrhines these small Primates remain as the only other group now known in North America which contains mem- bers that are early and generalized enough to admit of such a relationship. Other early Cenozoic families of North American Primates including Plesiadapidae, Carpolestidae, Anaptomorphidae, Phenacolemuridae, and Paromomyidae (if the latter two are regarded as distinct) exhibit extreme tooth specialization or reduction which entirely eliminates their known members from any ancestral relation to the South American Monkeys. It is clear, however, that if the dental form and arrangement of Ourayia uintensis was at all typical of the later Omomyidae as a whole, it would require a reversal of the trend toward reduction of the canines, seen in this species in order to reach the condition typical of the ceboid monkeys. Such a possibility seems at best rather unlikely. The question of the ancestry of the platyrrhine monkeys bears rather crucially on the interpretation of a number of more general assumptions inherent to the currently accepted higher categories of Primates, particularly the concept of the suborder Anthropoidea, as well as to the widely accepted succession of grades, from lemuroid to tarsioid, to monkey and etc., through which the ancestors of man and the other Higher Primates are commonly supposed to have passed. Perhaps the problem is largely semantic, resulting from the all too human tendency to superimpose an idealistically sub- divided terminology on what are actually continua of evolving lineages. Nevertheless, most of the various named higher -ategories of Primates have been, and presumably will continue to be, useful in talking about evolutionary relationhips within the order. One possible reaction might be to suspend judge- ment or discussion of relationships between early and late Cenozoic Primates in view of the partial and fragmentary evidence now available, but within the framework that has been set up by previous research it seems advisable to follow out some earlier suggestions to their logical conclusion. For instance, if platyrrhine monkeys were actually derived from anything like the Notharctus group or even from the omomyid 12 Postilla Yale Peabody Museum No. 54 prosimians, it is difficult to see how they could have passed through a grade of organization that need be qualified as tarsioid. If either of these groups are actually ancestral to the South American Monkeys, but not to the Old World Higher Primates, then it is also necessary to conclude that those features which are shared by Old and New World Higher Primates are the result of parallel evolution and that these two groups were independently derived from the Prosimu. In the latter case the taxon Anthropoidea consists of a grade in the sense of Huxley (1958) rather than a clade, in which the common ancestor of subsequent derivative stocks shares something of the definition which justifies the associa- tion of such subsequent groups within a single taxon. If Catar- rhini and Platyrrhini were derived from independent stocks of Prosimii, then Anthropoidea have a polyphyletic origin, even if such stocks belonged to the same major division of prosimians. When considering the various alternatives for the derivation of the Platyrrhini it may be noted that latest species of the genus Notharctus, and of Smilodectes as well, are rather large prosimians, having approximately the body size range seen in species of the living Malagasy genus Lemur or in the domestic cat. It seems implausible, although not impossible, that forms such as the pigmy marmoset could have descended from ances- tors of the size range of known notharctids. The smallest notharctids, species of the early Eocene genus Pelycodus, in comparable parts, have about twice the linear dimensions of the smaller species of Callithriv and are even larger compared to Cebuella, should the latter genus be sustained as distinct from Callithrix [Hapale|. Inasmuch as known species of Pely- codus give every evidence of being close to the origin of the taxon Notharctidae, there is little reason to posit that there ever were unknown smaller members of this subfamily from which marmosets such as Cebuella might more plausibly have been derived without marked size decrease at some intermediate period. One is therefore faced with the supposition that, if Notharctidae are in or near the ancestry of platyrrhines, mar- mosets have undergone a size reduction since their initial dif- ferentiation. This view has sometimes been put forward, but to date there is no paleontological evidence for it. Oct. 30, 1961 The Dentition of Ourayia 13 In conclusion, it is possible to say that in spite of the fact that late Eocene and Oligocene omomyids were specializing along distinct lines of their own, not foreshadowing Platyrrhini, it seems probable that Omomys and its immediate forebears are the most likely early Cenozoic prosimians to have a direct relationship to the rise of the South American Monkeys. Among principal evidences supporting this view are the obser- vations that Omomys, or one or more forms allied to it, was smaller than any known ceboids, had suitably unspecialized molar crown patterns together with small third molars, shared with some ceboids the otherwise nearly unique possession of a pericone cusp, and belongs to a group showing trends away from the primitive prosimian condition toward foreshortening of the rostrum, orbital enlargement, and vertical incisor em- placement. Moreover, Omomyidae are the only known family of ancient and undoubted Primates now known which possessed exactly the same dental formula as do the living Cebidae. Nevertheless, only in earliest omomyids are relative sizes of respective tooth types reasonably satisfactory for derivation of the tooth morphology characteristic of Oligocene-Recent South American Monkeys. 14 Postilla Yale Peabody Museum No. 54 Figure 1. Diagrammatic reconstructions of a sequence of representative omomyid species, approx. x 3. Dotted outlines hypothetical. These species may not represent a single phylum, but each is typical of the successive Epoch substage to which it belongs. Specimens on which this chart is based are as follows: Macrotarsius montanus (type) C. M. 9592 (reversed) ; Ourayia uintensis, P.U. 16431 (P, and M, reversed from right ramus): Hemiacodon gracilis (composite), part A—A.M.N.H. 12037, part B—Y.P.M. 16253, part C—Y.P.M. 12987-1; Omomys carteri (composite), part A—A.M.N.H. 12600, part B—Y.P.M. 16287 (reversed), part C—Y.P.M. 13219-2 (reversed). Oct. 30, 1961 EARLY OLIGOCENE EVOIGREINIE EVA E WwW = WW oO (oe) WwW MIDDLE The Dentition of Ourayia MACROTARSIUS OMOMYS 16 Postilla Yale Peabody Museum No. 54 Figure 2. Occlusal views of right upper, and left lower dentitions of Ouwrayia win- tensis, P.U. 16431, (M, reversed from right side), approx. x 5.5. Oct. 30, 1961 The Dentition of Ourayia il 18 Postilla Yale Peabody Museum No. 54 Figure 3. lateral view of right maxilla of Ourayia uintensis, P.U. 16431, approx. NGOs Oct. 30, 1961 Ss a _. The Dentition of Ourayia i] 20 Postilla Yale Peabody Museum No. 54 REFERENCES Clark, J., 1941. An anaptomorphid primate from the Oligocene of Montana. Journ. Paleo., v. 14, no. 5, pp. 562-563, 1 fig. Gazin, C. L., 1958. A review of the Middle and Upper Eocene Primates of North America. Smiths. Mise. Coll. v. 136, no. 1, pp. 1-112, 14 pl. Gregory, W. K., 1921. On the structure and relations of Notharctus, an American Eocene primate. Mem. Amer. Mus. Nat. Hist., v. 3, pt. 2, pp. 49-243, 84 fig., 36 pl. Huxley, J. S., 1958. Evolutionary processes and taxonomy with special reference to grades. Uppsala Univ. Arsskrift, No. 6, pp. 21-39. Leidy, J., 1873. Contributions to the extinct vertebrate fauna of the western territories. Rep. U.S. Geol. Surv. Terr. (Hayden), v. 1, pp. 1-358, 33 fig., 37 pl. Matthew, W. D. and W. Granger, 1915. A revision of lower Eocene Wasatch and Wind River Faunas. Part IV., Bull. Amer. Mus. Nat. Hist., v. 34, pp. 429-483, 52 fig., 1 pl. Osborn, H. F., 1895. Fossil mammals of the Uinta Basin. Expedition of 1694. Bull. Amer. Mus. Nat. Hist., v. 7, pp. 71-105, 17 fig. , 1902. American Eocene Primates, and the supposed rodent family Mixodectidae. Bull. Amer. Mus. Nat. Hist., v. 16, pp. 169-214, 40 fig. Wortman, J L., 1903-1904. Studies of Eocene Mammalia in the Marsh Col- lection, Peabody Museum. Part 2. Primates. Amer. Journ. Sci., 4th Ser., v. 15, pp. 163-176, 399-414, 419-436, v. 16, pp. 345-368, v. 17, pp. 23-33, 132-140, 203-214, 48 fig., 2 pl. wwe 3 2044 066 305 236 Date Due ALE HS oe PI Pr = Sige a Ae eee —— Sn OP Spawn Pom ERTS ROOTES TSS or A ITAA ALR ee amend 6A a ne a eee ~~ er paPrDnrae ra eX a ne a pr en - . Seer PTL EEE <r rete ae : me - ey : en ay Sin inlet oS ae Ci TT a a eel ee TT petal TT eC EN ae igh mn rene Sere t Oa ON a et eet ee a eS OLE PES Re ete eli pepernenss aad PLEA one em ete pate eee ee aeeietind ee aa a teat ge lA ee aie ee ett gp mathy Se anes Cheer faeyew ’ a4 - nt ‘. — : ep IT x r a bee wanes _ , iO eet ~ LO OS a epee ti SLe aenn - - CO gee OOF aN a ae EE OO OTL ee aacalae —, pie ntl Rae en I eee P-So ST eee a aa tc Pie a Oe OT Se ae eee OT eae Att” FOI eile atl i Pep PPP POOL. ee - ee eo se iccaane_ eee PLEO IAI ene ore a8 PE pen OO nde ela ”