The 81st Annual Meeting of the American Association of Physical Anthropologists (2012)

New earliest Eocene tarsal specimens of Cantius (Primates, Notharctinae) from central Wyoming


1Department of Anthropology and Archaeology, Brooklyn College, City University of New York, Brooklyn, New York, 2Department of Anthropology, Graduate Center, City University of New York, New York, 3NYCEP, New York Consortium in Evolutionary Primatology, New York, 4Department of Anatomical Sciences, Stony Brook University, Stony Brook, New York, 5Department of Vertebrate Paleontology, Florida Museum of Natural History, Gainesville, Florida

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Morphological patterns among the earliest known species of fossil euprimates are important for reconstructing phylogenetic relationships and evolutionary origins of modern Primates. Species of Cantius and Teilhardina are the earliest known adapiform and omomyiform euprimates, respectively. Fieldwork in the Bighorn Basin has recovered a partial calcaneus and astragalus of Cantius ralstoni from sites stratigraphically tied to the Paleocene-Eocene boundary. These tarsals appear to be the earliest known for Cantius. We compare the new material to a sample representing other C. ralstoni, other Cantius species, and Notharctus. Additionally, we make comparisons to material of penecontemporaneous Teilhardina, as well as other fossil euprimates. Finally, our observations are put in the context of a generically comprehensive extant sample of strepsirrhines, tarsiiforms, and platyrrhines. We utilize 3D models generated from microCT scans and preliminarily report results from five measurements: calcaneocuboid facet area, calcaneus total proximodistal length, calcaneus anterior segment proximodistal length; fibular facet slope; and astragalar trochlea width. Data show: 1) new C. ralstoni fossils are similar in size to other material known for this species. 2) As in previous work, no significant morphological trends through time except absolute size increase were documented for Cantius species; however, length of the anterior segment of the calcaneus was found to show significant negative allometry when regressed against measures of absolute size, which appears to explain previously noted differences in anterior segment elongation between Cantius and Notharctus. 3) The astragalar-fibular facet in Cantius is steeper on average than that in other sampled adapiform specimens and Teilhardina.

This research was supported by the National Science Foundation including: NSF 0333415 (NYCEP IGERT), NSF BCS-1125507 (DMB & ERS); EAR-0640076, and EAR-0719941 (JIB)

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