Currently, humans are the only primates that live in North America. But he discovered that 30 million years ago, the last bastion of non-Homo sapiens primates on this continent was a small, skinny primate. And researchers have finally been able to piece together the history of its survival.
New research published in human evolution journal The paper reveals how a primate species called Ekmowetshala came to North America after all other primates went extinct, possibly millions of years ago.
Ekmowechashara is a species that has been known for decades, with fossil records first discovered in the 1960s, researchers said. However, the story of this ancient primate has been shrouded in mystery for many years.
“Because of its unique morphology and expressed only by tooth remains, its place in the evolutionary tree of mammals has been the subject of controversy and debate,” says the University of Kansas Biodiversity Institute and Museum of Natural History. says Kathleen Last, a doctoral candidate in paleontology. is the lead author of the study, said in a press release.
“The prevailing opinion is to classify it as a primate. However, the timing and appearance of this primate in the North American fossil record is extremely unusual. It suddenly appeared in the Great Plains fossil record more than 4 million years after the extinction of North American primates.”
Primates arrived in North America about 56 million years ago, but after the transition from the Eocene to the Oligocene epoch 34 million years ago, North America became much colder and drier, making the continent once more common. North America is no longer the best habitat for roaming primates.
“Millions of years later, Ekumowechashala will appear like a wandering gunslinger in a Western movie, but it’s just a blip in the long evolutionary trajectory,” Rust said.
This is a phenomenon known as the “Lazarus effect,” in which a species that appears extinct in one region suddenly reappears in the fossil record millions of years later.
Researchers have been searching for a definitive answer to the origin of this primate for years. Did some primates survive the Eocene-Oligocene transition and evolve into Ekmowechashala, or did the primates come from somewhere else entirely?
To put the pieces of the Ekmowechashala puzzle together, Rust examined fossilized teeth and jaws found in the US state of Nebraska, as well as fossils collected decades ago in China.
Co-author Chris Beard, senior curator of vertebrate paleontology at the University of Kansas and Rust’s doctoral advisor, first collected fossils in the 1990s from the Nadu Formation of the Baishi Basin in China’s Guangxi Zhuang Autonomous Region. Was.
When he first found the fossil, he immediately noticed that it resembled Ekmowechashala.
“When we were working there, we never expected to find a relative of this strange North American primate, but as soon as we literally lifted our jaws and looked at it, we were like, ‘Wow. I thought, ‘This is it,”’ Beard said in the release. “It didn’t take a long time and we had to do all kinds of detailed analysis. We knew what it was. We have a collection here at KU that includes Ecmowe, which is known in North America. There are several important fossil remains, including by far the best Chashara upper molars to date. The upper molars are very distinctive and very similar to those from China. , this turned out to be the deal breaker.”
However, a more in-depth analysis was needed, and that’s where Rust comes in.
Ekmowechashala fossils have been reported from three regions in the western United States: South Dakota, Oregon, and Nebraska. For this analysis, Rust examined fossils from Nebraska, which constitute the oldest known North American record of Ekmowechashala, to provide a better comparison with older Chinese fossils.
Rust’s analysis of these fossils revealed similarities in the teeth and jaws of the Nebraska and China fossils, revealing an evolutionary relationship and an important bridge in the history of Ekumowechashala. say the researchers.
The apparent identification of an older “sister taxon” to Ekmowechashala, native to China, suggests that this is where Ekumowechashala first developed. This species, discovered in China, was named Palaeophodites, meaning “ancient wanderer.”
“We collected a significant amount of morphological data to create evolutionary trees using phylogenetic reconstruction software and algorithms,” Rust said. “This evolutionary genealogy suggests that there is a close evolutionary relationship between the North American Ekumowechashala and the Chinese paleophodites, which Chris and his colleagues discovered in the 1990s. Our analysis clearly supports this hypothesis.”
This fossil footprint suggests that Ekmowetshashala, like many of the inhabitants of North America today, were immigrants.
“(It) evolved in Asia and migrated to North America, probably via Beringia, during a surprisingly cool period,” Rust said.
It’s unclear exactly how long the Ekumowechashara existed, but fossils of this primate date from about 29.5 million to 27.8 million years ago, suggesting that the species is at least 200 million years old. It is suggested that it lasted for many years.
Rust said this new study sheds light on primate evolution during a time of major environmental upheaval in North America.
“It’s important to understand how past biota responded to such changes,” she says. “About 34 million years ago, all primates in North America were unable to adapt and survive. North America lacked the conditions necessary for survival. This meant that in an era of dramatic climate change, , highlighting the importance of accessible resources for nonhuman primate relatives.
“Understanding this story is not only humbling, but also helps us understand the depth and complexity of the dynamic planet we live on. You can understand the forces of evolution and the influence of environmental factors.”
