Ancestral facial morphology of Old World higher primates.

Abstract

Fossil remains of the cercopithecoid Victoiapithecus recently recovered from middle Miocene deposits of Maboko Island (Kenya) provide evidence ofthe cranial anatomy of Old World monkeys prior to the evolutionary divergence of the extant subfamilies Colobinae and Cercopithecinae. Victoriapithecus shares a suite ofcraniofacial features with the Oligocene catarrhine Aegyptopithecus and early Miocene hominoid Afropithecus. AU three genera manifest supraorbital costae, anteriorly convergent temporal lines, the absence of a postglabellar fossa, a moderate to long snout, great facial height below the orbits, a deep cheek region, and anteriorly tapering premaxilla. The shared presence of these features in a catarrhine generally ancestral to apes and Old World monkeys, an early ape, and an early Old World monkey indicates that they are primitive characteristics that typified the last common ancestor of Hominoidea and Cercopithecoidea. These results contradict prevailing cranial morphotype reconstructions for ancestral catarrhines as Colobus-orHylobates-like, characterized by a globular anterior braincase and orthognathy. By resolving several equivocal craniofacial morphocline polarities, these discoveries lay the foundation for a revised interpretation of the ancestral cranial morphology of Catarrhini more consistent with neontological and existing paleontological evidence.

The Lacrimal Fossa of Cercopithecoidea, with Special Reference to Cladistic Analysis of Old World Monkey Relationships

“…Of the 6 extinct colobine genera for which ade quate cranial remains are known, Libypithe cus and Mesopithecus possess long nasal bones, Libypithecus and Dolichopithecus pos sess narrow interorbital septae, and Liby pithecus, Paracolobus and Dolichopithecus possess long faces [2,6,[20][21][22][23][24], Among fossil colobines, only Cercopithecoides uniformly possesses 'colobine' craniofacial features [6,25,26], Indeed, the colobine affinity of Liby pithecus is indicated only by its dental and endocranial morphology [27][28][29], It is more parsimonious to assume that these fossil colo bines retained a primitive cercopithecine-like condition, and that the modern genera are hence derived, than to propose independent evolution of these features in the Cercopithecinae and in the fossil colobine genera men tioned above. Our argument is corroborated by the recent discovery that members of both extant cercopithecid subfamilies share a mod erately long muzzle and narrow interorbital septum with the fossil subfamily Victoriapithecinae, the sister group to all modern Old World monkeys [17][18][19], Statements citing facial lengthening as the sole correlate of an exclusively lacrimal fossa [4,6] are also questionable in light of the retention of a maxillary contribution to the fossa among moderately long-faced cercopithecoids (Macaca, Cercopithecus, Allenopithecus, Libypithecus, Paracolobus and Doli chopithecus) and hominoids (Gorilla and Pari). We suggest that the presence of a de rived, exclusively lacrimal fossa may also be associated with narrowing of the interorbital septum.…”

“…We have suggested elsewhere [17][18][19] that the ancestral cercopithecoid face may actually have been typified by a moderately prog nathic snout with long, narrow nasal bones and a relatively narrow interorbital septum, like those of guenons and macaques. Our argument is based in part on the observation that facial features previously considered to be autapomorphic for Cercopithecinae occur in fossil and extant colobine genera as well.…”

Facial anatomy of Victoriapithecus and its relevance to the ancestral cranial morphology of old world monkeys and apes

“…Consequently, the new Maboko specimens are 6-8 million years older than comparable cranial elements of previously known fossil cercopithecoids with the exception of a partial maxilla of Prohylobates from Buluk (Leakey, 1985). Together with 14 other fragmentary maxillae found in the same strata 330 B. R. BENEFIT AND M. L. McCROSSIN at Maboko since 1973, the specimens permit reconstruction of the facial and anterior cranial morphology of the middle Miocene cercopithecoids (Benefit and McCrossin, 1991).…”

Morphological integration of the cranium in Homo, Pan, and Hylobates and the evolution of hominoid facial structures

“…It will also allow an assessment of whether similar patterns can be found in distantly related groups with similar craniofacial characteristics (i.e., a short face). Taking into account craniofacial similarities shared among stem catarrhines (e.g., Aegyptopithecus and Sadaanius), early hominoids (e.g., Afropithecus), and early cercopithecoids (e.g., Victoriapithecus), several authors have hypothesized that the ancestral hominoid morphotype is cercopithecine-like, with an elongated face (Benefit & McCrossin, 1991;Bilsborough & Rae, 2015;Zalmout et al, 2010). If this is the case, then short-faced hylobatids and hominins presumably evolved convergently from more prognathic ancestors.…”