New fossil discovery illuminates the lives of the earliest primates


Date:
February 24, 2021
Source:
The Graduate Center, CUNY
Summary:
A new fossil discovery is central to primate ancestry and adds
to our understanding of how life on land recovered after the
Cretaceous- Paleogene extinction event 66 million years ago that
wiped out all dinosaurs, except for birds.



FULL STORY ========================================================================== Graduate Center, CUNY/Brooklyn College professor was part of a discovery
of the first fossil evidence of any primate, illustrating the earliest
steps of primates 66 million years ago following the mass extinction
that wiped out all dinosaurs and led to the rise of mammals.


========================================================================== Stephen Chester, an assistant professor of anthropology and paleontologist
at the Graduate Center, CUNY and Brooklyn College, was part of a team of
10 researchers from across the United States who analyzed several fossils
of Purgatorius, the oldest genus in a group of the earliest-known primates called plesiadapiforms. These ancient mammals were small-bodied and ate specialized diets of insects and fruits that varied across species.

This discovery is central to primate ancestry and adds to our
understanding of how life on land recovered after the Cretaceous-Paleogene extinction event 66 million years ago that wiped out all dinosaurs,
except for birds. This study was documented in a paper published in the
journal Royal Society Open Science.

"This discovery is exciting because it represents the oldest dated
occurrence of archaic primates in the fossil record," Chester said. "It
adds to our understanding of how the earliest primates separated
themselves from their competitors following the demise of the dinosaurs." Chester and Gregory Wilson Mantilla, Burke Museum Curator of Vertebrate Paleontology and University of Washington biology professor, were
co-leads on this study, where the team analyzed fossilized teeth found
in the Hell Creek area of northeastern Montana. The fossils, now part of
the collections at the University of California Museum of Paleontology, Berkeley, are estimated to be 65.9 million years old, about 105,000 to
139,000 years after the mass extinction event.

Based on the age of the fossils, the team estimates that the ancestor of
all primates (the group including plesiadapiforms and today's primates
such as lemurs, monkeys, and apes) likely emerged by the Late Cretaceous
-- and lived alongside large dinosaurs.

"Stephen Chester's high-caliber impactful research in this area
with Brooklyn College students has significantly contributed to our understanding of the environmental, biological, and social dependencies
that ultimately led to the evolution of primates," said Peter Tolias,
dean of the School of Natural and Behavioral Sciences.

This is not the first big find Chester has been involved with. While this latest discovery is unique in that it focused on one group of mammals -
- primates -- in 2019, Chester, along with current collaborator Wilson Mantilla, was a key member of a groundbreaking discovery that revealed
in striking detail how many life forms -- including mammals, turtles, crocodiles, and plants -- recovered after the asteroid impact that wiped
out the dinosaurs.

Chester, who specializes in the early evolutionary history of primates
and other placental mammals, was also a co-author of that peer-reviewed scientific paper in Science magazine with Denver Museum of Nature &
Science researchers.

In 2015, while at Brooklyn College, Chester was also the lead author
on a paper published in the Proceedings of the National Academy of
Sciences on this same genus of primate, Purgatorius. His co-authored
paper described the ankle bones of Purgatorius, which is still the
oldest fossil evidence that primates lived in the trees shortly after
the extinction of the dinosaurs.

Chester did some of the research for this project at his Evolutionary Morphology Laboratory, where he trains undergraduate students in all
aspects of paleontological research at Brooklyn College. While students
were not directly involved in this latest discovery and subsequent paper, Chester has brought many lucky students from his paleoanthropological
fieldwork classes to Wyoming, Montana, and North Dakota to a region
essentially known as the "paleontological mecca of the West" to dig for
primate fossils from 66 million years ago. These trips connected Brooklyn College students with Chester's scientific collaborators and other
students from the Denver Museum of Nature & Science, the Smithsonian's
National Museum of Natural History, the Yale Peabody Museum, the Royal
Ontario Museum, and the Marmarth Research Foundation.

The team of researchers who collaborated alongside Chester and Wilson
Mantilla in this latest discovery includes William Clemens, University of California Museum of Paleontology; Jason Moore, University of New Mexico; Courtney Sprain, University of Florida and University of California,
Berkeley; Brody Hovatter, University of Washington; William Mitchell,
Minnesota IT Services; Wade Mans, University of New Mexico; Roland Mundil, Berkeley Geochronology Center; and Paul Renne, University of California, Berkeley.

========================================================================== Story Source: Materials provided by The_Graduate_Center,_CUNY. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Gregory P. Wilson Mantilla, Stephen G. B. Chester, William
A. Clemens,
Jason R. Moore, Courtney J. Sprain, Brody T. Hovatter, William S.

Mitchell, Wade W. Mans, Roland Mundil, Paul R. Renne. Earliest
Palaeocene purgatoriids and the initial radiation of stem
primates. Royal Society Open Science, 2021; 8 (2): 210050 DOI:
10.1098/rsos.210050 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/02/210224100849.htm

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