Teeth smaller than a fingertip reveal the first primate ancestor
Science Daily
March 3, 2026
AI-Generated Deep Dive Summary
Paleontologists have uncovered tiny fossils of Purgatorius, the earliest known primate relative including humans, in Colorado’s Denver Basin—marking the southernmost discovery of this species ever found. This breakthrough reshapes our understanding of how early primates evolved and spread across North America after the dinosaur extinction. The fossils, consisting of minute teeth and ankle bones, suggest that Purgatorius likely lived in trees and inhabited regions further south than previously believed.
Purgatorius, a shrew-sized mammal, first appeared shortly after the asteroid impact that wiped out the dinosaurs 66 million years ago. Until now, its remains were only found in Montana and parts of Canada, leaving a gap in the fossil record for southern regions. The new findings, published in *Journal of Vertebrate Paleontology*, reveal that Purgatorius spread southward soon after the mass extinction, with evidence suggesting it diversified across what is now North America.
The discovery was made possible through an intensive screen-washing process, which uncovered several tiny teeth and bones from sediment at the Corral Bluffs study area. These fossils are so small they could fit on a baby’s fingertip, but their significance is huge: they may belong to a new species of Purgatorius due to unique features not seen in previously known specimens.
This discovery challenges earlier assumptions that the asteroid impact caused widespread forest destruction, which might have limited Purgatorius’ southward spread. Instead, it suggests that plant life recovered quickly, allowing these early primates to thrive in more diverse environments than once thought. The find also highlights how sampling bias can skew our understanding of fossil records—underscoring the importance of thorough and innovative fossil-hunting techniques.
For readers interested in science, this research offers fresh insights into primate evolution and the rapid recovery of life following a mass extinction. It not only fills a significant gap in the fossil record but also emphasizes the resilience of early mammals in repopulating the planet after such a catastrophic event.
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Originally published on Science Daily on 3/3/2026