Scientists have discovered small fossils such as: purgatoryby far the oldest known relative of all primates, including humans, living in the southern part of North America. The discovery is helping researchers better understand how some of the first primate relatives spread and evolved in the aftermath of the dinosaur extinction.
The origin of primates and their early migration across North America remains one of the most intriguing and debated topics in paleontology. purgatory It was a small mammal about the size of a shrew that appeared shortly after the mass extinction event that wiped out the dinosaurs approximately 65.9 million years ago. It is thought to be the oldest known paleoprimate.
For decades, purgatory It was only found in present-day Montana and southwestern Canada, even though rock formations of similar age exist throughout much of North America. Meanwhile, a wider range of related paleoprimates have been discovered in the southwestern United States, but their fossils are about 2 million years younger. This gap in time and geography has long puzzled scientists.
Southernmost Purgatorius fossil ever discovered
Recent research published in peer-reviewed journals Journal of Vertebrate Paleontology Report the southernmost known fossil purgatory. The remains were recovered from the Coral Bluffs research area in the Denver Basin, Colorado.
“This discovery helps fill a gap in understanding the geography and evolution of our earliest primate relatives,” explains lead author Stephen Chester, Ph.D., associate professor at Brooklyn College and the City University of New York Graduate Center (CUNY), who led the study with colleagues at the Denver Museum of Natural Science (DMNS).
“The presence of these fossils in Colorado suggests that ancient primates originated in the north, then spread south, and diversified shortly after the end-Cretaceous mass extinction,” Chester added.
Researchers had previously wondered whether the species’ apparent absence from southern Montana reflected actual biological limitations rather than a lack of fossil evidence.
“Purgatorius’ ankle bones show features that indicate Purgatorius was an arboreal animal, so we initially thought that the absence of Purgatorius in southern Montana might be related to widespread forest devastation caused by an asteroid impact 66 million years ago.
“But our paleobotanical colleagues suggested that plant recovery in North America was proceeding rapidly, leading us to believe that Purgatorius must also be in more southern regions. Perhaps we didn’t look hard enough.”
Small teeth discovered after intensive fossil research
To test the idea, Chester and his colleagues used an extensive screen cleaning process designed to recover very small fossils that are often missed by traditional collection methods.
This research was supported in part by a nearly $3 million collaborative grant from the National Science Foundation. The funding will support a wide-ranging project led by Dr. Tyler Lyson of DMNS focused on understanding how life recovered after the mass extinction event best known for ending the age of dinosaurs.
Students and volunteers spent countless hours cleaning the deposit and carefully sorting through the material. Their efforts led to the discovery of many fossilized fish, crocodiles, and turtles. There were some small ones among them. purgatory Each tooth is small enough to fit on the tip of a baby’s finger.
Evidence of a possible new species
The teeth may represent something even more important, says Dr. Jordan Crowell, a DMNS postdoctoral researcher who played a key role in the study.
What’s particularly “interesting” about these teeth, Crowell explains, is that they may actually belong to an earlier species. purgatory.
“These specimens have a unique combination of features compared to known species of Purgatorius, but we await the recovery of additional material to assess whether these fossils represent a new species,” he added.
Why are small fossils important?
The discovery also highlights a major challenge in paleontology. The apparent absence of early primate relatives in the southern interior of western North America may have been influenced by sampling bias rather than their actual absence.
For nearly 150 years, researchers working in this region have relied heavily on traditional surface collections. While these methods are effective at finding large fossils that are visible to the naked eye, small fossils like newly discovered teeth can easily be overlooked.
“Thanks to a long-term partnership with the city of Colorado Springs, which owns the land where the fossils were collected, and countless hours of work by volunteers and interns who dig through the soil for rare vertebrate fossils, we are building an impressive dataset that provides insight into how life, including our earliest primate ancestors, bounced back after one of the worst days for life on Earth,” added co-author Dr. Lyson.
“Our results show that small fossils can be easily overlooked,” concludes Dr. Chester. “More intensive searches, especially using screen cleaning techniques, will undoubtedly uncover many more important specimens.”
The study also includes co-author Dr. David Krause, senior curator of vertebrate paleontology at DMNS.
