Discovery of ancient primate fossils in Colorado reveals southern migration of early ancestors following dinosaur extinction

Paleontologists find Purgatorius teeth in Colorado, proving our earliest primate ancestors spread across North America far earlier than previously recorded.

By: AXL Media

Published: Mar 3, 2026, 4:49 AM EST

Source: The information in this article was sourced from Taylor & Francis Group

Breakthrough in primate biogeography

New fossil evidence discovered in Colorado is providing scientists with critical insights into the origins and movement of the earliest primate relatives. Purgatorius, a shrew-sized mammal that lived approximately 65.9 million years ago, was previously thought to be restricted to the northern regions of Montana and southwestern Canada. The recovery of these fossils at the Corral Bluffs study area in the Denver Basin marks a significant southern expansion of the known range for this species, situated approximately 500 miles south of prior discovery sites.

Evidence of rapid post-extinction diversification

The presence of Purgatorius in Colorado indicates that archaic primates originated in northern North America and spread southward almost immediately following the asteroid impact that ended the Cretaceous Period. Dr. Stephen Chester, an associate professor at Brooklyn College and lead author of the study, noted that the discovery fills a long-standing gap in the evolutionary record. While researchers initially believed the destruction of southern forests by the asteroid might have prevented Purgatorius from migrating, recent paleobotanical evidence suggests that plant life recovered quickly enough to support the arboreal lifestyle of these early ancestors.

Screen washing techniques reveal microscopic remains

The breakthrough was made possible through an intensive screen-washing process funded by a 3 million dollar grant from the National Science Foundation. Unlike traditional surface collecting techniques that have focused on large fossils for over a century, this method involves washing vast amounts of sediment to find microscopic remains. This systematic approach allowed a team from the Denver Museum of Nature & Science to identify several tiny teeth that would fit on the tip of a finger. These specimens exhibit a unique combination of features that may eventually lead to the classification of a new, earlier species of Purgatorius.