Meeting Abstract

P1.141  Tuesday, Jan. 4  Early hominin evolution: a review of major morphological adaptations and problems in applying cladistics PORTER, N.C.*; ALEMSEGED, Z.; Barnard College, New York; California Academy of Sciences, San Francisco ncp2115@barnard.edu

Hominin fossils preserve evidence of the major evolutionary changes that occurred since human’s split from the chimpanzees about 7 ma. Unfortunately, due to the fragmentary nature of the fossil record, the vast majority of human ancestors are only known to us to a limited extent. Here, I review the major unique adaptations within the hominin lineage prior to the emergence of the genus Homo, the currently recognized early hominin species and their unique morphological traits, the paleoenvironmental and ecological conditions in which these species evolved, and the problems associated with determining phylogenetic relationships among fossil taxa. Bipedalism and changes in dentition are two key characteristics that emerged early in our evolutionary history and define the hominin clade in relation to other apes. Changes in dentition correspond to, and may have been driven by, changes in diet and ecology. Although the broad trends in hominin evolution are relatively clear, there is still much debate concerning the relationships among fossil hominin taxa. The phylogenetic species concept is widely used in paleoanthropology; however, some aspects of its application face unique problems when dealing with fossil species. Parsimony analyses which are used to determine cladistic relationships among fossils face a suite of problems relating to sample size, character choice, closely related taxa, and observer bias that limit the production of robust results.