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キーワード:
Artiodactyla, Bovidae, Middle Pliocene, Ethiopia, eastern Africa
要旨:
Hominid-bearing sites of the north western part of the Woranso-Mille research area, dated to between 3.7 and 3.8 Ma., yield 10 species of Bovidae. The evolutionary stages of the most common species fit quite well this radiometric age. The most abundant bovid is a new species of Aepyceros, of large size, with upright, lyrated horn-cores; it is clearly distinct from the impalas of younger sites in the same area, and from those sampled at Hadar. A new species of Tragelaphus is also common; its horn-cores exhibit reduced anterior keel and antero-posterior compression foreshadowing the most common form at Hadar. A single partial Ugandax skull, despite some primitiveness, may fit into the variation range of U. coryndonae from Hadar. Other tribes are rare; the virtual absence of reduncines is a major difference from younger sites, but the occurrence of a cephalophine and of Neotragus is worth noting. This assemblage unambiguously indicates an environment with a significant component of arboreal vegetation.
