New research shakes up the sloth family tree

JUNE 6, 2019

by American Museum of Natural History

New studies by two research teams published today in the journals Nature Ecology and Evolution and Current Biology challenge decades of accepted scientific opinion concerning the evolutionary relationships of tree sloths and their extinct kin. The research teams used different molecular tools—the protein collagen in one case and the mitochondrial genome in the other—but they reached nearly the same results. The concurrent findings are significant because they provide molecular evidence that appears to overturn a longstanding consensus, based on the study of anatomical features, regarding how the major groups of sloths are related to one another.

Corresponding authors Ross D. E. MacPhee of the American Museum of Natural History and Frédéric Delsuc of the French National Centre for Scientific Research (CNRS) at the University of Montpellier noted that, although their research groups worked separately, they were in communication.

"All of us were initially surprised by our results because they thoroughly contradicted what seemed to be the accepted view based on anatomy," said Delsuc.

"Exceptional results demand exceptional verification," continued MacPhee, a curator in the Museum's Department of Mammalogy, "That's why we arranged with the journals to publish our papers simultaneously, to emphasize that corroboration is a crucial part of good science."

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