Proconsul Nyanzae Research Articles

New specimens of Proconsul from Koru, Kenya

The morphological and metrical definitions of the three species of Proconsul: Proconsul africanus, Proconsul nyanzae and Proconsul major , are reviewed. New finds of large fossil primates from the Lower Miocene deposits at Koru, Kenya are described and assigned to two of these species; P. africanus and P. major . The large sample of P. major from Koru permits a more complete understanding of the morphology and variability of this species and necessitates a revised diagnosis. The increased range of variation for this species is discussed in the light of sexual dimorphism and species variability in extant African hominoids.

Hominoid primates from a new Miocene locality named Meswa Bridge in Kenya

The remains of a species of Proconsul from early Miocene deposits at Meswa Bridge are described. Associated dental, mandibular, maxillary and cranial specimens represent several immature individuals. They are equivalent in size to Proconsul nyanzae but differ morphologically, particularly in the greater breadth and degree of flare of the deciduous and permanent molars, but lack of adult individuals from Meswa Bridge makes it difficult to compare them adequately with existing species. They are therefore left unassigned as an indeterminate species of Proconsul.

Restoration of the Holotype of Proconsul nyanzae

The crushed palate and lower face of the holotype of Proconsul nyanzae has been prepared using the acetic acid technique. The prepared and conserved fragments have been restored to their natural positions using a synthetic cement and polyethylene glycol wax (Carbowax 4000) to fill the gaps. Preparation revealed the inferior margin of the right orbit, the inferior border of the nasal bones, and a posterior divergence of the palate which has now been corrected. The restored face of P. nyanzae shows the orbits to have been wider apart than those of Proconsul major, both absolutely and relatively, and that it had a long narrow nose and palate. It differs from Proconsul africanus, which has the shortest and broadest face of all Proconsul species, and from P. major which has a much longer narrower face.

Note on the placement of the most complete 'Kenyapithecus africanus' mandible.

It is suggested that the most complete <i>‘Kenyapithecus africanus’</i> mandible, KNM-RU 2087, represents a male pongid. As such, it should be considered a Dryopithecus africanus specimen, srather than a D. nyanzae specimen. Its placement in D. africanus, as a male of that species, explains all of its features.

Sexual dimorphism inDryopithecus africanus.

Among the numerous specimens presently classified withinDryopithecus africanus only one can be identified as a male of this species. Poor sampling is not the reason for the unequal numbers of male and female specimens. Rather, the males have been classified elsewhere, specifically withinDryopithecus nyanzae and "Kenyapithecus africanus." The specimens to be transferred from these two taxa are proved to be males ofD. africanus. The newly transferred males are compared with the females to show the cranial dimorphism of the species.

On the supposed "Kenyapithecus africanus" mandible.

ENOUGH is known about Ramapithecus species (including “Kenyapithecus wickeri”) to say that a morphological complex characterizes the earliest hominids. This complex, described in detail elsewhere1,2, includes anteroposterior shortening of the jaw, reduction of canine height, squaring of the molars, lowering of the molar cusps, molarization of the premolars, thickening of cheek tooth enamel, increase in interstitial wear, and increase in the verticality of the incisors and symphyseal region.

Lower dentition of Kenyapithecus africanus.

A mandible of Kenyapithecus africanus, with many of the teeth preserved, has been found at Kathwanga, Rusinga Island, Kenya. Previously the lower dentition of this species was unknown—except by inference from the mandible fragments with the crowns of the teeth broken off. The age of this member of the Hominidae is early Miocene.