Achievement

Trainee Lauren Halenar completed her dissertation research on the paleobiology of the extinct Brazilian monkey Protopithecus and the evolutionary history of its relatives, the living howler monkeys, who have enlarged hyoid bones which may facilitate their roaring calls. The fossil's hyoid is not preserved, but comparative study showed that the skull base of howler monkeys is modified to make room for their enlarged hyoid. Protopithecus did not have such modification and thus may not have possessed a large hyoid, although it is possible that sufficient throat space might have been available as a result of the fossil's large size. Combining several lines of evidence, Lauren hypothesized that Protopithecus retained the inferred morphology of the earliest member of the howler lineage. In fact, she demonstrated that the oldest howler fossil (13 million years old) is the most similar to extant forms while several later fossils look more primtive, the reverse of the usual pattern.