Andrew Hill New cercopithecoids and a hominoid from Department of Anthropology, 12·5 Ma in the Tugen Hills succession, Yale University, P.O. Box Kenya 208277, New Haven, CT 06520, U.S.A. E-mail: [email protected] The early evolutionary history of the cercopithecoids is poorly under- stood, primarily due to a lack of fossil material from between 15 and about 9 Ma. Cercopithecoid primate specimens from a fossil site in Meave Leakey the Ngorora Formation of the Tugen Hills, Kenya, belong to the Department of Palaeontology, genus Victoriapithecus, possibly a new species. These fossils are National Museums of Kenya, associated with a hominoid specimen that resembles Proconsul, and P.O. Box 40658, Nairobi, another tooth of a catarrhine, also probably hominoid. The locality is Kenya. BPRP#38, in the Kabasero type section of the Ngorora Formation, E-mail: [email protected] and well dated at 12·5 Ma. If the hominoid specimen is confirmed as Proconsul, it would be one of the most recent recorded. The relatively John D. Kingston diverse mammal fauna from the site in some ways resembles that of Department of Anthropology, Fort Ternan. The site is underlain, and not far removed in time, from Emory University, one of the best fossil macro-floras in Africa, which indicates lowland 1557 Pierce Drive, Atlanta, rainforest conditions in this portion of the Rift Valley at 12·6 Ma. GA 30322, U.S.A. 2002 Academic Press E-mail: [email protected] Steve Ward Department of Anatomy, Northeastern Ohio Universities College of Medicine, Rootstown, OH 44272, U.S.A. E-mail: [email protected] Received 15 December 2000 Revision received 12 June 2001 and accepted 14 June 2001 Keywords: Hominoidea, Cercopithecoidea, Miocene, Journal of Human Evolution (2002) 42, 75–93 Ngorora, Tugen Hills, doi:10.1006/jhev.2001.0518 Kenya. Available online at http://www.idealibrary.com on Introduction (Le Gros Clark & Leakey, 1951), a man- dible fragment and an isolated lower molar The early history of the Cercopithecoidea in from Loperot, Kenya (Szalay & Delson, Africa is sparse (Gundling & Hill, 2000). A 1979) and 16 specimens including man- handful of primitive Old World monkeys is dibular and maxillary fragments and isolated known from a number of early Miocene sites teeth from Buluk, northern Kenya (Leakey, in East Africa ranging in age from approxi- 1985). In north Africa, early cercopithecoids mately 19–17 Ma. These include an M2 are known from two early Miocene locali- from Napak, Uganda (Pilbeam & Walker, ties. The specimens include three damaged 1968), an isolated M3 from Ombo, Kenya mandibles from Wadi Moghara, Egypt 0047–2484/02/010075+19$35.00/0 2002 Academic Press 76 . ET AL. (Simons, 1969), and a mandible fragment within the Cercopithecidae. Benefit’s re- from Gebel Zelten, Libya (Delson, 1979). analysis of this material and a later collection From the supposed Middle Miocene at made by Pickford, along with her detailed Ongoliba, Congo, an M3 of a monkey has comparisons with a large number of modern been reported (Hooijer, 1963). In contrast cercopithecoids, indicate that the Maboko to these sparse and isolated occurrences, a monkeys represent a single species, V. large collection of monkey cranial and post- macinnesi (Benefit, 1987). Harrison (1987) cranial fragments belonging to the genus reached a similar conclusion. The extended Victoriapithecus has been recovered from the time interval from which the collection is 15 Ma, Middle Miocene site of Maboko derived resulted in a slightly high level of (von Koenigswald, 1969; Benefit, 1987, variation in the specimens. Benefit identified 1993; Benefit & McCrossin, 1989, 1993). a number of primitive dental traits Another recently discovered occurrence unique to these early monkeys, and at least of Victoriapithecus material is from the three derived dental traits (and possibly Kipsaramon site complex in the Tugen many more) common to the modern sub- Hills. At site BPRP#89, for example, dated families Colobinae and Cercopithecinae, at 15·5 Ma (Hill et al., 1991; Behrensmeyer but exclusive of the Victoriapithecinae. She et al., 2002) there is a partial left mandible concluded that the modern subfamilies are with M2 and M3, as well as isolated teeth more closely related to one another than (e.g., KNM-TH 31013, a left P4; and either is to the Victoriapithecinae. She KNM-TH 31014, a right P4). therefore proposed that the Victoriapitheci- This early cercopithecoid material has nae be raised to family rank (Benefit, been attributed to two genera, Prohylobates 1987, 1993, 1994, 1999; see also Harrison, and Victoriapithecus, which share several 1987). primitive dental traits and which differ The large collection of Maboko monkeys, largely in their absolute size and molar pro- although providing exceptional evidence for portions (Leakey, 1985; Benefit, 1987, the primitive characteristics of the Victoria- 1993). Prohylobates is known from few pithecidae, leaves many questions un- occurrences in the early Miocene of east and answered concerning the mode and timing north Africa (e.g. from Buluk, Wadi of the origin of modern monkeys. What was Moghara, Gebel Zelten) whereas Victoria- the origin of the Cercopithecidae, and the pithecus is well known from the exceptional modern cercopithecid subfamilies? The ear- Maboko collection. Detailed studies by liest cercopithecid reported from Africa is a Benefit (1987, 1993, 1994, 1999, 2000; colobine from Ngeringerowa, a site complex Benefit & McCrossin 1989, 1993, 1997)of within the Ngorora Formation of the Tugen the numerous specimens from Maboko have Hills succession (Benefit & Pickford, resulted in a good understanding of these 1986), which has now been dated by the early monkeys which provides a sound basis Baringo Paleontological Research Project for comparison of new discoveries of Middle to between 9·5 Ma and 8·8 Ma (Deino, Miocene cercopithecoids. personal communication). There is also an Earlier studies identified two species of isolated colobine tooth from the site of the genus Victoriapithecus in the Maboko Nakali (Aguirre & Leakey, 1974; Benefit & collection, V. macinnesi and V. leakeyi (von Pickford, 1986). An isolated cercopithecoid Koenigswald, 1969; Delson, 1973; Simons right P4 (KNM-BN 1251) from the & Delson, 1978; Szalay & Delson, 1979). Ngorora site discussed here (BPRP#38, These species were regarded as forming a =2/1) was also described in Benefit & separate subfamily, the Victoriapithecinae, Pickford (1986). Later, Benefit (1999) 77 mistakenly equates this Ngorora site with Pickford, 1997), and the Lukeino molar, Nakali. However, Nakali is not in the Tugen also from the Tugen Hills (see Hill, 1999)]. Hills, but on the eastern side of the Rift, and The present paper does not rectify this is several million years younger than deficiency significantly, but adds one, BPRP#38. and possibly two, hominoid teeth to the The single right P4 from BPRP#38 has inventory. been the only evidence of African cerco- pithecoids yet reported from the crucial six million year interval between the last occur- Geology and dating rence of the Victoriapithecidae, around 15 Ma, at Maboko and Kipsaramon, and The Ngorora Formation was first investi- the first occurrence of the Colobinae at gated and mapped by Chapman, working Ngeringerowa at 9·5–8·8 Ma. The further with the East African Geological Research specimens described here from 12·5 Ma Unit (EAGRU), and first described by deposits in the Tugen Hills succession Bishop & Chapman (1970). Further notes represent an interval in time which could on the fauna appeared in Bishop et al. provide answers to important questions (1971) and the unit was discussed in more concerning the origin and radiation of the detail in Chapman (1971). Aguirre exca- two modern cercopithecid subfamilies. vated vertebrate fossil localities in the The record of African Miocene hominoids Ngorora Formation for one season (Aguirre is also poorly known after 14 Ma until the & Leakey, 1974), and Pickford undertook appearance of hominids in the Pliocene. more detailed investigations (Bishop & Again, the Ngorora Formation in the Tugen Pickford, 1975; Pickford, 1975a, 1978). Hills provides the next evidence in time. Initial age determinations are summarized in A molar tooth of uncertain attribution Chapman & Brook (1978). The work of the (KNM-BN 1378) is known from site Baringo Paleontological Research Project BPRP#60 in the Bartabwa section of the (BPRP) on the formation is reported in Hill Formation, which is not yet precisely dated, et al. (1985, 1986; Hill, 1995, 1999) and but is probably about 12 Ma (Bishop & more specific information concerning radio- Chapman, 1970; Hill & Ward, 1988; Hill, metric dating and paleomagnetic stratigra- 1994, 1999). A premolar similar to Proconsul phy appear in Tauxe et al. (1985) and Deino (KNM-BN 10489) comes from site et al. (1990). BPRP#65 (Hill et al., 1985; Hill & Ward, The unit is defined as lying between the 1988; Hill, 1994, 1999), and is dated at Tiim Phonolites beneath, and the Ewalel about 12·4 Ma (Deino et al., 1990). It is Phonolites above, and in the type section at associated with a canine (KNM-BN 10556) Kabasero there are about 370–400 m of in very poor condition, that could also be sediments. Volcaniclastic deposits of the hominoid, but if it is, it is unlikely to be from Ngorora Formation are extensive geographi- the same species as the premolar (Hill & cally, occurring in disjunct fault bounded Ward, 1988). Apart from these few speci- basins, located mainly in the north of the mens there is little from later in time than Tugen Hills range, but significant outcrops, the Fort Ternan site, dated at 14 Ma, which such as at Ngeringerowa, occur nearly has produced a variety of hominoids, but no 40 km further south. monkeys, until the Pliocene [additional The formation is also extensive in time, hominoid specimens in this interval include representing over 4 Ma, a remarkably Otavipithecus (Conroy et al., 1992), Sambu- long period for continental sediments in rupithecus from the Samburu Hills (Ishida & Africa.