1Department of Anatomical Sciences, Stony Brook University, 2Department of Evolutionary Anthropology, Duke University
Thursday 1:30-1:45, Broadway III/IV
Recent work at Birket Qarun Locality 2 (BQ-2), an earliest late Eocene (~37 Ma) locality in the Fayum Depression of northern Egypt, has led to the recovery of abundant remains of primates and other mammals, including new specimens attributable to Biretia, the oldest undoubted anthropoid from Afro-Arabia. Among the new Biretia specimens are more complete mandibular remains, a partial maxilla, a number of isolated teeth, and a partial calcaneus. The maxilla of Biretia megalopsis preserves a vertically oriented nasolacrimal duct, a small part of the orbital rim, alveoli for the upper canine and P2-3, and the crowns of P4-M1. The fragment of the orbital rim is small (~3.5 mm), but based on the preserved morphology, the predicted orbital diameter of the specimen (plotted against M1 area) suggests that Biretia was a diurnal primate. If this inference is correct, the orbitopalatal fusion of Biretia, previously interpreted as a possible indication of orbital hypertrophy and nocturnality, would require an alternative functional explanation. The mandibular symphysis is unfused, providing new support for the hypothesis that symphyseal fusion evolved independently in parapithecids. The P2 is one-rooted, suggesting that the isolated three-rooted tooth previously interpreted as a P2 of Biretia fayumensis might be a very small P3. The calcaneus has a short and tightly curved ectal facet. Phylogenetic analysis incorporating this new evidence continues to place Biretia as a basal parapithecoid, and inclusion of recently described specimens of the older African primates Azibius and Algeripithecus confirms that these genera are not anthropoids but stem strepsirrhines.
Funded by the U.S. National Science Foundation (BCS-0819186) and The Leakey Foundation.