New Haven, Conn. -- The origins and earliest branches of primate evolution are clearer and more ancient by 10 million years than previous studies estimated, according to a study featured on the cover of the Jan. 23 print edition of the Proceedings of the National Academy of Sciences.
The paper by researchers at Yale, the University of Winnipeg, Stony Brook University, and led by University of Florida paleontologist Jonathan Bloch reconstructs the base of the primate family tree by comparing skeletal and fossil specimens representing more than 85 modern and extinct species. The team also discovered two 56-million-year-old fossils, including the most primitive primate skeleton ever described.
In the two-part study, an extensive evaluation of skeletal structures provides evidence that plesiadapiforms, a group of archaic mammals once thought to be more closely related to flying lemurs, are the most primitive primates. The team analyzed 173 characteristics of modern primates, tree shrews, flying lemurs with plesiadapiform skeletons to determine their evolutionary relationships. High-resolution CT scanning made fine resolution of inaccessible structures inside the skulls possible.
"This is the first study to bring it all together," said co-author Eric Sargis, associate professor of anthropology at Yale University and Assistant Curator of Vertebrate Zoology at Yale's Peabody Museum of Natural History. "The extensive dataset, the number and type of characteristics we were able to compare, and the availability of full skeletons, let us test far more than any previous study."
At least five major features characterize modern primates: relatively large brains, enhanced vision and eyes that face forward, a specialized ability to leap, nails instead of claws on at least the first toes, and specialized grasping hands and feet. Plesiadapiforms have some but not all of these traits. The article argues that these early primates may have acquir
Contact: Janet Rettig Emanuel