The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)


New specimens of Australopithecus anamensis from Kanapoi, Kenya

J. MICHAEL PLAVCAN1, CAROL V. WARD2 and FREDRICK K. MANTHI3.

1Department of Anthropology, University of Arkansas, Fayetteville, 2Pathology and Anatomical Sciences, University of Missouri, 3Department of Earth Sciences, National Museums of Kenya

March 26, 2015 1:15, Grand Ballroom C Add to calendar

Australopithecus anamensis represents the origins of the Australopithecus-Homo clade, but remains poorly represented in the fossil record. For this reason, it is significant that renewed fieldwork at Kanapoi, Kenya, from 2012-2014 has yielded new A. anamensis fossils. These include a partial mandible with complete dentition, maxillary fragment preserving left C-P4 and a partial lower face, the rest of the previously published partial dentition KNM-KP 47953, numerous isolated teeth, and fragmentary postcrania.

The new specimens confirm the morphologies previously identified as diagnostic of early A. anamensis. The maxilla demonstrates the large, vertically implanted canine root and rounded lateral nasal margin seen in the only other maxillary specimen from Kanapoi. The two new anterior mandibular dentitions confirm the relatively wide lower lateral incisors that likely contribute to the differences in overall toothrow morphology between A. anamensis and A. afarensis. The mandibular symphysis is strongly sloped, canine tooth roots large, postcanine teeth with strong buccal flare, and the typical A. anamensis canine-P3 complex is present. Although the distinctive sloping protoconid is present, the mandibular P4 talonid is more expanded than in any other Kanapoi specimen, suggesting more variable talonid size than previously appreciated.

The new fossils confirm the distinctive morphology of A. anamensis compared with A. afarensis, while expanding known variation in premolar morphology. The new fossils are consistent with the hypothesis of morphological change throughout this lineage, perhaps related to changes in dietary behavior.

Research funded by NSF BCS 1232393 and 1231675; Wenner-Gren Foundation; LSB Leakey Foundation