Ruggles-Gates Award – Ashley Bales

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Award Holder: Ashley Bales
University: New York University
Title of Research: The phylogenetic position of Proconsul

The goal of this project is to clarify and potentially resolve the phylogenetic relationships of the Miocene East African primate ProconsulProconsul, one of the best-known fossil catarrhines (old-world monkeys + apes), dating from 21 million years ago to 14 million years ago, is pivotal to understanding hominoid origins and the early stages of human evolution. concerning the inferred phylogenetic position of Proconsul. Initially Proconsul was inferred to be closely related to the great apes, but was soon pushed down the evolutionary tree to the base of the ape lineage.  Even this position has been challenged, however, with some researchers suggesting it may be even more primitive and should be considered as part of a lineage diverging before the last common ancestor of old-world monkeys, apes and humans.  The main goal of this project is to clarify the long-standing debate.  This will be accomplished by: 1) collecting metric and non-metric data on an extensive set of morphological characters; and 2) conducting a phylogenetic analysis using the latest methods.  Further, while this project focuses on Proconsul it will be the most thorough phylogenetic analysis using morphological data to address questions of catarrhine evolution and as such, will infer ancestral morphotypes for all clades, resulting in a comprehensive list of derived characters for the hominin clade, rooted in a thorough exploration of anthropoid comparative morphology.    

My research took me to Kenya and Uganda, where Proconsul originates, and much of my data collection on extant taxa occurred in the collections of the Museum fur Naturkunde in Berlin.   For 11 months, I traveled to museum collections in Europe, Africa and the U.S.  Visiting this range of collections allowed me to gather data from 11 fossil taxa and 20 extant species for a total of over 600 individual specimens.  My final data set is the most comprehensive morphological data set yet compiled for anthropoid taxa, including 824 characters spread across 4 functional complexes: the skull, pelvis, forelimb and foot. Such an extensive data set is necessary to confront the problem of where to put Proconsul on the primate evolutionary tree because it may fall so close to the divergence of the old world monkey and ape lineages.

I am currently analyzing these data using the same methods developed for building evolutionary trees from genetic sequence data.  These methods have improved dramatically in the past decades as the field of genomics has progressed.  By applying these same methods to the analysis of an extensive morphological data set, I hope to resolve the difficulties in placing Proconsul on the primate evolutionary tree.  Preliminary analyses indicate a surprising result: that Proconsul may not have been an ape.  Proconsul’s morphology suggests it is more primitive and supports the hypothesis that Proconsul is a stem catarrhine, from a lineage diverging prior to the origination of the group containing old-world monkeys, apes and humans.  This suggests it may be necessary to reassess our understanding of the morphology at the base of the ape and human clade.