New Clues on Early Primate Evolution Unveiled

Paleontologists discover southernmost fossils of Purgatorius, the earliest known primate relative

Published on Mar. 4, 2026

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A new scientific study led by paleontologist Stephen Chester, an Anthropology professor at the CUNY Graduate Center and Brooklyn College, has uncovered the southernmost discovery of Purgatorius fossils ever found in Colorado's Denver Basin. The tiny teeth fossils suggest the earliest known primate relatives may have originated in the north and spread southward after the extinction of the dinosaurs.

Why it matters

This discovery helps fill a gap in understanding the geography and evolution of our earliest primate relatives after the mass extinction event that wiped out the dinosaurs. It challenges previous assumptions about the distribution of archaic primates and suggests more intensive fossil sampling could uncover additional important specimens.

The details

The research, published in the Journal of Vertebrate Paleontology, was conducted in collaboration with scientists from the Denver Museum of Nature & Science. The newly discovered fossils show a unique mix of features, potentially belonging to a previously unknown early species of Purgatorius, a small tree-dwelling mammal considered the earliest known relative of all primates, including humans.

  • The fossils were recovered in 2026 through careful screen washing of ancient sediments at the Corral Bluffs study area in Colorado's Denver Basin.
  • Purgatorius lived about 66 million years ago, shortly after the extinction of the dinosaurs.

The players

Stephen Chester

A paleontologist and Anthropology professor at the CUNY Graduate Center and Brooklyn College, who served as the lead author on the study.

Jordan Crowell

A CUNY Graduate Center alumnus and co-author on the study.

Tyler Lyson

A co-author on the study from the Denver Museum of Nature & Science.

David Krause

A co-author on the study from the Denver Museum of Nature & Science.

Purgatorius

A small, tree-dwelling mammal that lived about 66 million years ago and is considered the earliest known relative of all primates, including humans.

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What they’re saying

“This discovery helps fill a gap in understanding the geography and evolution of our earliest primate relatives after dinosaur extinction.”

— Stephen Chester, Paleontologist and Anthropology professor (miragenews.com)

“Our results demonstrate that small fossils can easily be missed. With more intensive searching, especially using screen-washing techniques, we will undoubtedly discover many more important specimens.”

— Stephen Chester, Paleontologist and Anthropology professor (miragenews.com)

What’s next

The nearly $3 million collaborative grant from the National Science Foundation that Chester and his colleagues received in 2023 will continue to fund Brooklyn College undergraduate research assistants who sift through excavated sediment, uncovering fossils of Purgatorius and other vertebrates that lived in the immediate aftermath of the dinosaurs' extinction.

The takeaway

This discovery challenges long-standing assumptions about the distribution of archaic primates and suggests that more intensive fossil sampling in underexplored regions could uncover additional important clues about the early evolution and spread of our primate ancestors after the mass extinction event that wiped out the dinosaurs.