Scientists have discovered tiny new fossils, including: purgatoryby far the oldest known relative of all primates, including humans, living in the southern part of North America. The discovery provides new insight into how primates first evolved and spread across continents.
The origin and early geographical history of primates has long caused debate among researchers. purgatoryIt is a small mammal, about the size of a shrew, that appears in the fossil record shortly after the dinosaurs went extinct about 65.9 million years ago. It is widely considered to be the oldest paleoprimate.
Although rock formations from this era have been found throughout North America, fossils of this type have until now been confined to parts of Montana and southwestern Canada. Other early primate relatives have been discovered in the southwestern United States, but they date back about 2 million years, creating gaps in the fossil record that have puzzled scientists.
According to findings published in a peer-reviewed paper, Journal of Vertebrate Paleontologythe newly discovered fossil represents the southernmost record. purgatory. They were discovered in the Coral Bluffs Study Area in Colorado’s Denver Basin.
Evidence of southward dispersal after dinosaur extinction
“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.
Fossilized ankle bones purgatory They probably lived in trees. Because of this, researchers once suspected that its absence south of Montana was related to widespread deforestation caused by an asteroid impact 66 million years ago.
“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, as Purgatorius’ ankle bones show features that indicate Purgatorius was an arboreal animal.
“But our paleobotanical colleagues suggested that recovery of the plant in North America was proceeding rapidly, leading us to believe that Purgatorius must also be in more southern regions. Maybe we didn’t look hard enough.”
Screen cleaning reveals small teeth
To investigate more thoroughly, Dr. Chester and colleagues at DMNS used an intensive screen cleaning process to sift through the sediment to find extremely small fossils. This effort was supported in part by a nearly $3 million joint grant from the National Science Foundation. The foundation is funding a wide range of research initiatives led by DMNS’ Dr. Tyler Lyson that focus on how life recovered after the mass extinction that ended the age of dinosaurs.
Students and volunteers carefully washed and separated the large amounts of sediment. Their research led to the discovery of numerous fish, crocodile, and turtle fossils, and eventually some smaller fossils. purgatory The teeth are small enough to fit on the tip of a baby’s finger.
Dr. Jordan Crowell, a postdoctoral fellow at DMNS and a key member of the research team, said what makes these teeth particularly “intriguing” is the possibility that they belong to an even earlier species. purgatory.
“The 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.
Overlooked fossils and new insights
This finding also suggests that the apparent absence of early primate relatives further south in the Western Interior may have been influenced by sampling bias. For nearly 150 years, paleontologists in this region have relied primarily on surface sampling methods. This method yields large fossils that are visible to the naked eye, while smaller specimens tend to remain hidden.
“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.
