A research paper co-authored by 可乐视频 and CUNY-based researchers has revealed that picrodontids鈥攁n extinct family of placental mammals that lived several million years after the extinction of the dinosaurs鈥攁re not primates, as previously believed.
The paper was published on January 10 in and is significant in that it settled a paleontological debate that has been brewing for more than 100 years while helping to paint a clearer picture of primate evolution.
Stephen Chester
The research was done by Stephen Chester, the senior author and an associate professor of anthropology at 可乐视频 and the CUNY Graduate Center; Jordan Crowell, the lead author and adjunct lecturer in the Department of Anthropology at 可乐视频 and a Ph.D. candidate at the CUNY Graduate Center; and John Wible, curator of mammals at the Carnegie Museum of Natural History.
For the last 50 years, paleontologists have believed picrodontids, which were no larger than a mouse and likely ate foods such as fruit, nectar, and pollen, were primates, based on features of their teeth that they share with living primates. But by using modern CT scan technology to analyze the only known preserved picrodontid skull in the world at 可乐视频鈥檚 Mammalian Evolutionary Morphology Laboratory. Crowell worked with Chester and Wible to determine they are not closely related to primates at all.
Chester, who serves as Crowell鈥檚 Ph.D. adviser, has both a professional and personal interest in this research. It was Chester鈥檚 renowned colleague and 鈥渁cademic grandfather,鈥� Professor Emeritus Frederick Szalay from Hunter College (CUNY) and the CUNY Graduate Center, who, in 1968, first convincingly classified picrodontids as primates based on evidence from fossilized teeth. Szalay studied the teeth of the only known picrodontid skull, Zanycteris paleocenus, for his research鈥攖he same skull this team examined with the new technology that led to their discovery.
鈥淭丑别 Zanycteris cranium was prepared and partially submerged in plaster around 1917, so researchers studying this important specimen at the American Museum of Natural History were not aware of how much cranial anatomy was hidden over the last 100 years鈥� Chester said. 鈥淢icro-CT scanning has revolutionized the field of paleontology and allows researchers to discover so much more about previously studied fossils housed in natural history museum collections.鈥�
鈥淲hile picrodontids share features of their teeth with living primates, the bones of the skull, specifically the bone that surrounds the ear, are unlike that of any living primate or close fossil relatives of primates,鈥� Crowell said. 鈥淭his suggests picrodontids and primates independently evolved similarities of their teeth likely for similar diets. This study also highlights the importance of revisiting old specimens with updated techniques to examine them.鈥�
CT scan technology revealed previously unknown bones of the skull (colored on the right) that helped demonstrate that picrodontids are not primates as previously believed.
The research was funded by grants Chester and Crowell secured through 可乐视频 from the National Science Foundation and The Leakey Foundation. Chester and Crowell are also currently working on several additional externally funded research projects focused on how primates and other mammals evolved following the extinction of the dinosaurs. They encourage undergraduates to contact them regarding funded research opportunities in the Mammalian Evolutionary Morphology Laboratory.
