PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024 Number 3350, 36 pp., 12 ®gures, 2 tables October 31, 2001 New Early Pliocene Cercopithecidae (Mammalia: Primates) from Aramis, Middle Awash Valley, Ethiopia STEPHEN R. FROST1 ABSTRACT The Middle Awash Research Project has collected a large sample of fossil cercopithecids from the Aramis, Kuseralee, and Sagantole drainages in the Middle Awash paleoanthropolog- ical study area of Ethiopia. These sites have been securely dated to 4.4 Ma. The craniodental material from this assemblage supports the diagnoses of two distinct new genera and species, which are described here. Pliopapio alemui is a mid-sized papionin represented by a complete cranium, several partial jaw fragments, and many isolated teeth. Kuseracolobus aramisi is a medium-sized colobine represented by several maxillae, mandibles, and other cranial frag- ments, as well as by isolated teeth. Stratigraphically associated postcranial remains will be discussed in a separate report. Pliopapio alemui is distinctive from other known African papionins in the combination of its cranial, mandibular, and dental morphology. It lacks the diagnostic facial features of Par- apapio, as well as the ¯attened muzzle dorsum, facial fossae, and maxillary ridges of Papio. Moreover, it does not possess any of the derived dental and cranial specializations of Thero- pithecus. Kuseracolobus aramisi is larger than all modern African colobines, but smaller than all known Cercopithecoides, Paracolobus, and Rhinocolobus. It is distinctive from Cercopi- thecoides and the colobine from Leadu in its symphyseal, corporal, and gonial morphology, and from Libypithecus, Paracolobus, and Rhinocolobus in its facial morphology. This early Pliocene sample ®lls a temporal gap between the terminal Miocene and later Pliocene sites and documents the existence of two new cercopithecid taxa, increasing known diversity in the family. 1 New York Consortium in Evolutionary Primatology, Ph.D. Program in Anthropology, City University of New York, and Division of Paleontology, American Museum of Natural History. Copyright q American Museum of Natural History 2001 ISSN 0003-0082 2 AMERICAN MUSEUM NOVITATES NO. 3350 INTRODUCTION this paper are based on the limited number of relatively complete specimens. While the The Cercopithecidae are relatively com- isolated teeth are only diagnosable to sub- mon and diverse in most Pliocene and Pleis- family, they are assigned to the same two tocene fossil assemblages from sub-Saharan species as the more complete material based Africa. During this period, the subfamily on size and a lack of evidence to the con- Cercopithecinae is represented by eight gen- trary. era or subgenera while the Colobinae is rep- resented by at least ®ve (Szalay and Delson, INSTITUTIONAL ABBREVIATIONS 1979; Delson, 1984, 1988, 1994). Few of these taxa, however, are represented in the KNM National Museums of Kenya, Nairobi, Early Pliocene. The locality of Aramis in the Kenya Awash River valley of Ethiopia has yielded NME National Museum of Ethiopia, Addis Ababa, Ethiopia the hominid Ardipithecus ramidus (White et NMT National Museum of Tanzania, Dar es al., 1994, 1995). The large cercopithecid Salaam, Tanzania sample from Aramis and sites of similar age MB Berlin Museum, Berlin, Germany in the Middle Awash adds considerably to our knowledge of cercopithecid evolution SYSTEMATIC PALEONTOLOGY during this period. The craniodental anatomy and systematics of these cercopithecids are CLASS MAMMALIA LINNAEUS, 1758 described here. ORDER PRIMATES LINNAEUS, 1758 Between 1992 and 1999, the Middle INFRAORDER CATARRHINI E. GEOFFROY, 1812 Awash Research Project collected and cata- FAMILY CERCOPITHECIDAE GRAY, 1821 logued 925 cercopithecid specimens from lo- calities within the Aramis, Kuseralee, and SUBFAMILY CERCOPITHECINAE GRAY, 1821 Sagantole drainages. This sample comes TRIBE PAPIONINI BURNETT, 1828 from the Aramis Member of the Sagantole Pliopapio, new genus Formation between the GaÁala Tuff Complex TYPE SPECIES: Pliopapio alemui, new spe- (GATC) and the Daam Aatu Basaltic Tuff cies. (DABT). These tephra have been radiomet- GENERIC DIAGNOSIS: A genus of African rically dated to 4.39 6 0.03 and 4.39 6 0.05 papionin, distinguished from Parapapio, Lo- Ma respectively (Renne et al., 1999). The phocebus, and Cercocebus by the presence size, precise stratigraphy, and dating of this of a clear anteorbital drop, although this is sample make it one of the best documented not as distinct as in most Papio and Man- in the African Pliocene. drillus. In this aspect, its pro®le is most sim- From a limited initial sample, Wolde- ilar to that of Macaca, but Pliopapio has a Gabriel et al. (1994) listed three cercopithe- relatively longer muzzle. It is different from cid species at Aramis based on preliminary Papio (Papio), Gorgopithecus, Lophocebus, identi®cations by Delson: cf. Paracolobus Cercocebus, and Mandrillus in that the muz- sp., cf. Colobinae sp. ``A'' (sensu Eck, 1977) zle lacks postcanine and suborbital fossae. and cf. Parapapio sp. On the basis of the The absence of maxillary ridges distinguish- current, vastly expanded craniodental sam- es it from Papio, Theropithecus (Omopithe- ple, two new genera and species are diag- cus) and Mandrillus. The muzzle dorsum is nosed here, one colobine and one cercopithe- saddle-shaped and rounded in paracoronal cine. In the postcranial sample, two and pos- section. In these aspects it is similar to Ther- sibly three morphs can be identi®ed. None of opithecus oswaldi (sensu Leakey, 1993, as is the postcranial specimens are directly asso- used throughout this paper), but is unlike the ciated with any of the craniodental material, ¯attened dorsum and squared paracoronal and their af®nities and functional interpreta- section found in Papio (including Dinopithe- tions will be presented elsewhere. cus) and Mandrillus. Relative to neurocranial This is one of the largest Early Pliocene breadth, the rostrum is narrow in comparison samples of fossil cercopithecids; however, with those of all known African papionins, the diagnoses for the two taxa described in although it is in the lowest end of variation 2001 FROST: CERCOPITHECIDAE 3 for Papio, Mandrillus, and Macaca. Crush- with complete but damaged dentition, found ing in the anterior portion may contribute to by Awoke Amzaye in December 1995. this impression, but cannot account for it en- HYPODIGM: See appendix 1. tirely. HORIZON: All specimens are derived from Unlike those in Parapapio, Cercocebus, the Aramis Member of the Sagantole For- and Lophocebus, the cranial vault is separat- mation, between the GATC and DABT, and ed from the brow ridges by a distinct are therefore dated to 4.4 Ma (Renne et al., ophryonic groove. The temporal lines in the 1999). holotype male remain widely separated and DESCRIPTION: The most complete specimen do not form a sagittal crest, as opposed to is the holotype male skull ARA-VP-6/9332 the situation in Theropithecus, Gorgopithe- (see ®g. 1). The mandible is attached to the cus, Papio (Dinopithecus), and Paradoli- cranium by a thin layer of matrix that pre- chopithecus. vents the two from being safely separated. While the mandibular symphysis is shal- Therefore, the palate and much of the cranial lower and more sloping in pro®le than that base are not available for observation. Of the of most papionins, it is shorter and more main cranial regions, only the left zygomatic rounded than that of Parapapio ado (from is completely missing. The right orbit is Laetoli and Kanapoi) or the papionin from damaged and lacks much of the right half, Lothagam. In these latter taxa the symphysis except for one triangular portion around the is even longer and more sloping, with the zygoma. The right zygomatic arch is mostly incisive alveolar process projecting more an- present, but crushed, missing only the region teriorly, producing a more procumbent inci- around the temporojugal suture. The right sor row. Corpus fossae are absent, distin- maxilla and mandible are weathered, reveal- guishing it from most Papio (Papio)(P. h. ing the roots of the teeth. The other cranial kindae females have very slight fossae, and specimens are all considerably more frag- some P. izodi lack them), Gorgopithecus, mentary. ARA-VP-6/437 (see ®g. 2) is a par- Theropithecus (Omopithecus), Mandrillus, tial right male maxillary fragment with the and Lophocebus. dorsal surface up to the piriform aperture, the The molars are higher crowned, more roots of the canine and fourth premolar, and straight-sided, and less ¯aring on average complete central incisor and third premolar. than those of Papio, Macaca, Mandrillus, ARA-VP-1/1723 (®g. 2) is a partial right fe- and Lophocebus, and far less so than those male maxilla preserving the canine through of Cercocebus. As in most papionins, but un- third molar. ARA-VP-1/1007 (®g. 2) is a like Mandrillus and Cercocebus, the premo- slightly crushed left female premaxillomax- lars are not particularly large relative to the illary fragment with the rostral surface pre- molars. The mandibular incisors are nearly served nearly to the lateral border of the pir- vertically implanted, whereas those of Par- iform aperture, a damaged lateral incisor, and apapio ado from Laetoli and Kanapoi are complete canine through ®rst molar. more procumbent. Pliopapio alemui is smaller in cranial size ETYMOLOGY: The name refers to the Plio- than all known Theropithecus and Papio, cene age of the taxon and its papionin status. other than P. hamadryas kindae, P. angus- ticeps, and P. izodi, to which it is similar in Pliopapio alemui, new species size. It is sightly larger than all but the largest Macaca, such as M. thibetana and M. ne- SPECIFIC DIAGNOSIS: As for genus. mestrina. This cranial size estimate is con- ETYMOLOGY: Named in honor of Alemu ®rmed by centroid sizes computed from a Ademassu, Paleoanthropology Laboratory sample of 45 cranial landmarks (see ®g. 3). curator at the National Museum of Ethiopia In dental size, it is marginally smaller than responsible for assisting with preparation, Parapapio ado from Laetoli and Kanapoi, molding, and study of all Middle Awash specimens.