Fossil hyraxes (Hyracoidea: Mammalia) from the Late Miocene and Plio-Pleistocene of Africa, and the phylogeny of the Procaviidae
Date
2005
Authors
Pickford, Martin
Journal Title
Journal ISSN
Volume Title
Publisher
BERNARD PRICE INSTITUTE FOR PALAEONTOLOGICAL RESEARCH
Abstract
A palate with much of the dentition from Aragai, Lukeino Formation (6 Ma) Kenya, is the most complete known specimen of a Late
Miocene procaviid hyracoid. It shares several features with Dendrohyrax. The specimen is as large as the western tree hyrax, Dendrohyrax
dorsalis, but it is attributed to a new species. D. dorsalis ranges through the tropical forests of Central and Western Africa, from Uganda to
Gambia. As such the presence of a similar species at Lukeino provides evidence of the humid forest nature of the palaeoenvironment in
the Tugen Hills during the Late Miocene. The fossil hyracoid specimens from the Early Pliocene of Langebaanweg, South Africa, are
close in morphology to, but somewhat larger than, the extant bush hyrax, Heterohyrax brucei, but have some derived characters found in
Procavia capensis. The cheek teeth are brachyodont, the lower premolar row is complete with a well-developed p/1 and there is a long
diastema between the second incisor and the first premolar, all features recalling Heterohyrax. However, the depth of the mandible, the
hypsodonty of the lower incisor, and the length of the premolar row relative to the length of the molar row are similar to the condition in
Procavia and attest to the onset of molar enlargement relative to the rest of the dentition. In the overall context of the Procaviidae,
Procavia is the most derived genus, and the presence of a few Procavia-like features in the Langebaanweg fossils indicate that the species
concerned was probably already evident on the Procavia lineage, but the presence of several plesiomorphic characters reveals that
it is a primitive member of the lineage. These also reveal that the specimens do not belong to Procavia cf. antiqua into which they were
previously tentatively classified by Hendey (1976) as they are somewhat more derived. The detailed systematic status of the large
extinct hyracoid Gigantohyrax maguirei, Kitching, 1965, from Pliocene cave fillings at Makapansgat, South Africa, has not previously been
satisfactorily demonstrated, even though it is clear that most authors have considered it to be a procaviid closely related to Procavia.
Kitching (1965) compared it only to species of Procavia. Re-study of the original sample, as well as additional fossils (three partial skulls,
isolated upper premolar, fragment of mandible with a premolar) reveal that Gigantohyrax shares many features with the genus
Dendrohyrax, fewer with Heterohyrax and even fewer with Procavia. It is concluded that among the Procaviidae, Gigantohyrax is most
closely related to Dendrohyrax. The new discoveries of Late Miocene and Pliocene procaviids inKenya and SouthAfrica, when added to
recently described associated upper and lower dental elements of Meroehyrax bateae from the base of the Middle Miocene of Uganda,
permit a reappraisal of procaviid phylogeny. It is concluded that procaviids probably descended from Saghatheriidae, and that
Pliohyracidae did not give rise to procaviids as previously thought by some authors.