Fossil Reveals Ancient Primates Took Refuge in Texas

Directing a field project to recover Eocene fossils from West Texas, Kirk and colleague Blythe Williams of Duke University discovered Diablomomys dalquesti, a new genus and species of primate that dates back at least 43 million years.

"After several years of collecting new fossils, reviewing Texas' primate community and comparing it to other places in North America, we found a much more diverse group of primate species in Texas than we expected," Kirk said.

Fossil imprint of ancient primates found at Devil's Graveyard Formation in southwest Texas (Photo by Chris Kirk)

During the early part of the Eocene epoch, primates were common in the tropical forests that covered most of North America, scientists say.

Marking the start of the Eocene, about 55 million years ago, Earth heated up in one of the most rapid and extreme global warming events recorded in geologic history - a time marked by the emergence of the first modern mammals.

Over time, climate cooling caused North American primates to decline in abundance and diversity. By the end of the Eocene, about 33 million years ago, primates and most tropical species had almost disappeared from North America.

Kirk's discovery of late middle Eocene primates at the Devil's Graveyard Formation in southwest Texas reveals new information about how North American primates evolved during this period of animal reorganization.

"It seems that primates stuck around in Texas much longer than many other parts of the continent because the climate stayed warm for a longer period of time," he said.

While primates were disappearing in places like Utah and Wyoming during the late middle Eocene, "west Texas provided a humid, tropical refuge for primates and other arboreal animals," Kirk explained.

The anthropologists named the new primate Diablomomys dalquesti, combining "Diablo" to represent the Devil's Graveyard Formation (sand- and mudstones near Big Bend National Park) with Omomys, a related fossil genus.

The dalquesti species name honors Walter and Rose Dalquest, who donated the land on which the fossil was collected, known as Midwestern State University's Dalquest Research Site.

Walter was a Texas paleontologist and distinguished biology professor at Midwestern State University in Wichita Falls until his death in 2000.

The researchers published their discovery in the "Journal of Human Evolution" article, "New Uintan Primates from Texas and their Implications for North American Patterns of Species Richness during the Eocene."

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