The Late Miocene colobine monkeys from Aragai (Lukeino Formation, Tugen Hills, Kenya)

Description of new mandibular remains ofMicrocolobusfrom Nakali (ca. 10 Ma, Kenya): implications on the evolution of Miocene colobines

“…delsoni , with only a moderate offset in height between both cusps (Delson, 1971; De Bonis et al, 1990). According to the S. lukeinoensis diagnosis of Gommery et al (2022:476), the P 4 metaconid and protoconid are ‘almost of the same height’ in this taxon. A height differential in favor of the protoconid and a distally offset metaconid is observed in Ce.…”

“…8 Ma, Ethiopia) was also likened to Microcolobus (Suwa et al 2015), but given the small number of specimens from both Beticha and Ngerngerwa, no definitive conclusion has been made. The colobine Miocene fossil record is complemented, for the 7 -6 Ma period, by partial mandibles from the taxa Cercopithecoides bruneti, Paracolobus enkorikae, and Sawecolobus lukeinoensis (Hlusko 2007;Pallas et al 2019;Gommery et al 2022). Specimens belonging to these taxa include partially preserved symphyses, corpus and toothrows.…”

“…Cercopithecidae are sister taxa to the Victoriapithecidae (Szalay and Delson 1979, but see Benefit and Pickford 1986), an ancestral stock of small omnivorous and partly terrestrial monkeys documented in eastern and northern Africa (Benefit 1993(Benefit , 1999(Benefit , 2008Miller et al 2009;Locke et al 2020). In contrast to the African Plio-Pleistocene fossil record, the early phases of the colobine evolution in the late Miocene are poorly known (Delson 1973;Benefit and Pickford 1986;De Bonis et al 1990;Koufos et al 2003;Hlusko 2006Hlusko , 2007Frost et al 2009;Gilbert et al 2010;Suwa et al 2015;Pallas et al 2019;Gommery et al 2022). Hitherto, our knowledge of their masticatory adaptations has come from isolated dental elements from various fossil deposits in eastern and northern Africa, relatively complete mandibular, cranial and postcranial elements from Toros-Ménalla (Chad), partial skulls from Lukeino (Kenya), a partial skull from Wadi Natrun (Egypt), and a partial mandible from Ngerngerwa (or Ngeringerowa, Kenya).…”

Anatomy of the mandibular corpus of extant cercopithecids : taxonomy and variation

“…Such data are of paramount value to interpret the mandibular hominoid fossil record (White and Johanson, 1982;Chamberlain and Wood, 1985;Lockwood et al, 1996;White et al, 2000;Fabbri, 2006;Skinner et al, 2006;Lague et al, 2008;Haile-Selassie et al, 2015Ioannidou et al, 2022). Despite a rich fossil record (Freedman, 1957;Delson, 1973;Leakey, 1982;Benefit and Pickford, 1986;De Bonis et al, 1990;Frost and Delson, 2002;Leakey et al, 2003;Hlusko, 2006Hlusko, , 2007Jablonski and Leakey, 2008;Jablonski et al, 2008aJablonski et al, , 2008bNakatsukasa et al, 2010;Pallas, 2019;Gommery et al, 2022) and the great taxonomic and functional diversity of its extant representatives (Groves and Kingdon, 2013;Rowe and Jacobs, 2016a), a thorough examination of the corpus shape of extant Old World Monkeys (Cercopithecidae) on a large taxonomic scale is lacking, preventing the extrapolation of any taxonomical and ecomorphological considerations in extant and fossil representatives of this group.…”

“…Although useful to discriminate extant and fossil cercopithecid taxa, these parameters, usually in the form of a ratio also referred as mandibular robusticity (e.g., Pallas et al, 2019), do not fully characterize the complex shape of the cercopithecid corpus, including the development of the lateral prominence, submandibular fossae, and corpus fossae, which are considered taxonomically diagnostic. Indeed, corpus anatomy has been used in diagnosis of fossil (Freedman, 1957;Leakey et al, 1983;Benefit and Pickford, 1986;Frost and Delson, 2002;Leakey et al, 2003;Hlusko, 2006Hlusko, ,2007Pallas et al, 2019;Gommery et al, 2022) and extant cercopithecids (Frost, 2001;Groves, 2007;Gilbert et al, 2018) but the level of variation, and particularly the influence of sexual dimorphism, in traits such as the lateral prominences, for example, is unknown.…”