Primates appeared almost immediately after the dinosaurs disappeared, new research suggests

A band famous for production T. rex fossils have now given the earliest evidence of primates in fossil records, in what is a significant discovery.

The jaw bones and an assortment of teeth found in Hell’s Creek in northeastern Montana are the oldest primate fossils ever discovered, research published in the Royal Society Open Science.

Dating about 65.9 million years ago, these animals lived only 105,000 – 139,000 years after the Cretaceous-Paleogene extinction event, in which an asteroid eliminated most plant and animal species from Earth. The new work was led by Gregory Wilson Mantilla of the University of Washington and Stephen Chester of Brooklyn College and the University of New York.

“This is an important study because it documents the first primates ever discovered, pushing back the date of older primates to the oldest Paleocene, in addition to establishing greater diversity,” said Eric Sargis, a professor of anthropology at Yale University. who is not affiliated with the new study, said in an email.

Indeed, the age of these fossils is significant, as they suggest the ancestor of all primates, both extinct and existing, lived during the Mesozoic, especially in the late Cretaceous. Prior to this discovery, the earliest evidence of stem, or early, primates, from fossil records dates from the first 300,000 to 500,000 years of the Paleocene (post-Mesozoic era).

The newly discovered teeth and jaws belong to two different species: P. janisae and P. mckeeveri. Both species belong purgatory, the oldest known genus associated with primates. Other members of this group include P. unio and P. ceratops, and all are considered plesiadapiformes – a group of primate stems that includes purgatory and from which come all modern primates such as monkeys, monkeys (you included) and lemurs.

P. janisae was already known to paleontologists, but P. mckeeveri is a newly described species named in honor of a family that supported fieldwork in this area. Three teeth with hitherto unseen features purgatory it allowed scientists to declare the discovery of a new species.

The team studied these extinct creatures by examining a large collection of fossils at the University of California’s Museum of Paleontology, which houses the largest collection of fossils. P. janisae fossils. They also had other epoxy parts purgatory fossils to work with, as well as enlarged 3D models printed from microCT scans. The team also used a technique called “geometric morphometry” to digitize and compare the characteristics of fossils with other known species.

“This work was done with a large team that brought distinct and critical skill sets to this research, from geochronologists who were able to determine the age of these fossils to geologists who were able to decipher how these fossils were deposited.” said Mantilla in an email. “Also, we could not have done this work without the help of generous colleagues at the museums we worked for. [with] and landowners in Garfield County, Montana, who allowed us to work on their land. It was a great team effort. ”

Scientists do not yet know the exact timing for its appearance purgatory, but “the fact that there are two species” that appeared so soon after the mass extinction “implies that their ancestor was older than the two descending species,” Mantilla wrote. It is increasingly likely that the ancestor of plesiadapiformes “first appeared in the late Cretaceous, rather than in the Paleocene,” he said, meaning that the first proto-primates would have rubbed their elbows with dinosaurs.

As for the forerunner to purgatory, this is still a mystery. As Mantilla explained, some North Cretaceous fossils from North America have been suggested to be ancestral. purgatory, including rats Gypsonictops. It is probably more likely that “we have not yet found the ancestor in the fossil record,” he added.

These small placental mammals looked very similar to the squirrel, but purgatoryLike other plesiadapiformes, they “share dental traits with other primates,” Sargis said, adding that their teeth were “primate, not rodent-like.”

I asked Chester what makes a primate a primate, to which he replied:

This is an excellent question and a central issue for all researchers studying the origins of primates. Until we fully understand what makes a primate a primate, it is difficult to know when our primate ancestors moved away from other mammals. Many primates today have traits associated with grabbing, jumping, an herbal diet, improved vision, and intelligence. However, we know from fossil records that not all of these features evolved at exactly the same time. As paleontologists, we can trace this combination of features to primates that disappeared from the oldest Eocene about 56 million years ago. But as you travel back in time to the oldest Paleocene about 66 million years ago, it is clear that our first primate relatives, such as Purgatorius, had some, but not all, of these traits. . Two important feature suites that evolved very early in the evolution of primates were skeletal traits, such as grabbing hands and feet for life in trees, and dental traits, such as specialized molars for eating leafless plant products such as fruits. . This combination of traits allowed the first relatives of our primates to separate from their competition immediately after the extinction of the dinosaurs.

Ashows the new study, purgatory they were among the first mammals to succeed in Paleodinner, appearing “shortly after the catastrophe that destroyed the non-avian dinosaurs,” Mantilla explained. “They had some adaptations that allowed them to thrive in this disaster. First, they were trees – they spent most of their time up in the trees – and second, they had teeth that allowed them to feed on fruit and insects.

These features, it would seem, allowed purgatory to “grow and become a major part of the terrestrial ecosystem within a million years of the mass extinction event,” he added.

Mammals first appeared during the late Triassic, about 300 million years ago (we have been for some time!). The fact that primates managed to thrive after the disappearance of non-avian dinosaurs is not a huge surprise. Really, mammals took over quickly once the terrible lizards disappeared, giving birth to the Mammal Age about 10 million years after the Cretaceous-Paleogene extinction event.

After living in the shadow of the dinosaurs for hundreds of thousands of years, our time has finally come.