A discovery has shaken the field of paleontology by providing new clues about the early history of primates following the extinction of the dinosaurs. In Colorado, tiny fossils of Purgatorius, the oldest known relative of all existing primates, including humans, have been found. This finding offers us a window into the past about the origin and dispersion of these ancient mammals.
The research, published in Journal of Vertebrate Paleontology, addresses a long-standing enigma about how primates geographically expanded after the asteroid impact that marked the end of the dinosaurs. The fragments found, mainly teeth and jaws, help reconstruct aspects of their diet and lifestyle. It is suggested that Purgatorius lived in trees and fed on fruits and insects, characteristics that defined many later primates.
The dentition of Purgatorius reveals adaptations towards a more varied diet, which would have been crucial for its survival in a world recovering from the impact. This discovery in Colorado is significant because it is the first time remains of this species have been found outside of Montana and southwestern Canada.
The study was led by paleontologist Stephen Chester, a professor at Brooklyn College and The Graduate Center in New York, with the collaboration of scientists from the Denver Museum of Nature and Science. The presence of fossils in Colorado suggests that archaic primates might have originated in the north, later spreading southward after the mass extinction of the Cretaceous.
The analysis of the ankle bones of Purgatorius confirms its arboreal life, which initially led researchers to think they did not extend south due to the devastation of forests by the asteroid impact. However, studies in paleobotany indicated a rapid plant recovery in North America.
Thanks to exhaustive efforts of sediment collection and washing, numerous fossils were discovered, including those of fish, crocodiles, and turtles, and tiny teeth that could belong to an earlier species of Purgatorius. This suggests that the observed absence in the south could be due to a sampling bias, which often focuses on larger fossils.
This finding enriches our understanding of the evolution of primates and how they adapted after the extinction of the dinosaurs. It also refines the timeline of the diversification of placental mammals, tracing an evolutionary path that would culminate in higher primates and, eventually, humans.
