Pint-sized primates were first in North America

By Jeanna Bryner

updated 7:18 p.m. ET March 3, 2008

Leaping, furry mini-monkeys that were as small as mice crossed the Bering land bridge long before humans, representing North America's oldest known primates.

This new claim is based on the fossils of at least three individuals of this previously unknown species of extinct primate uncovered at a site near Meridian, Miss., scientists announced today. The researcher estimates the primate fossils date to about 55.8 million years ago.

If the age of the fossils is accurate, the new finding could indicate that early primates migrated across the land bridge that once connected Siberia with Alaska long before Homo sapiens that arrived some 12,000 to 14,000 years ago. The teeny primate crossover from Asia happened during the Paleocene-Eocene Thermal Maximum when global temperatures rose at a rate and magnitude similar to today's global warming.

"The primate itself appears new to science, and is thus a welcome addition to what is still a small 'Red Hot' fauna in Mississippi," said Philip Gingerich of the Museum of Paleontology at the University of Michigan, Ann Arbor, who wasn't involved in the recent discovery. "The site has the potential to be important, but the importance depends to some extent on whether it is really the age the author claims or not."

Called Teilhardina magnoliana, the mini monkey-like creature weighed just an ounce and would have leapt across treetops to snatch up insects and fruits.

"They were acrobatic little creatures," said K. Christopher Beard of the Carnegie Museum of Natural History in Pittsburgh, who details his finding in the March 4 issue of the journal Proceedings of the National Academy of Sciences.

Monkey map
Closely related species of Teilhardina have been found at sites in China, Belgium, France and Wyoming.

The fossil evidence from the international sites indicates Teilhardina inhabited North America, Europe and Asia at roughly the same time. Researchers have puzzled over the sequence of colonization, or how these tiny primates spread over much of the globe at a time when global climate and sea levels were changing rapidly.

Before the fossils were found in Mississippi, scientists thought Teilhardina migrated from Asia to Western Europe before moving on to North America.

To date the Mississippi fossils, Beard took advantage of the idea that sea level remains constant across the globe at any given time. By matching up erosion features caused by a falling sea level over long distances, Beard estimated the Mississippi fossils are older than Teilhardina fossils from Belgium and France. That suggests the primates moved from Asia to North America and then to Western Europe.

The standard for dating fossils, however, relies on carbon isotopes, Gingerich said.

The study "inexplicably contains none of the now-standard evidence of carbon isotope values that define both the Paleocene-Eocene boundary and the carbon isotope excursion," Gingerich said. "Without this, it is really not possible to know how old the new primate from the 'Red Hot' site is or what it means for mammalian biogeography."

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