The story of Ekmowechashara, the last primate to live in North America before Homo sapiens and the Clovisians, reads like a spaghetti western. A mysterious loner with gray hair defies adversity to survive on the American plains.
However, this story unfolded about 30 million years ago, just after the Eocene-Oligocene transition, during which large-scale cooling and drying occurred in North America and the continent became warmer. It has become inhospitable for primates who love water.
Today, paleontologists from the University of Kansas and the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing reveal the long-standing story of Ekmowechashala, based on fossilized teeth and jaws discovered both in Nebraska and China. We published evidence that sheds light on this in the journal Human Evolution. .
To do so, the researchers first needed to reconstruct its family tree, a task aided by the discovery of Ekmowechashala’s even more ancient Chinese “sister taxon,” which led the team to Paleophodites ( (or “Ancient Wanderer”). Fossil discoveries in China have solved the mystery of Ekmowechashala’s presence in North America, showing that it was an immigrant rather than a product of local evolution.
“This project focuses on highly distinctive primate fossils that have been known to paleontologists since the 1960s,” said lead author, KU’s Institute of Biodiversity and Museum of Natural History paleontology. said Kathleen Last, a doctoral candidate. “Due to its unique morphology and expression solely through the remains of its teeth, its place in the mammalian evolutionary tree is a subject of controversy and debate. There is widespread consensus towards its classification as a primate. However, the timing and appearance of this phenomenon is such that the inclusion of a primate in the North American fossil record is extremely unusual. Its sudden appearance in the Great Plains fossil record comes more than 4 million years after its extinction.
In the 1990s, Dr. Rust’s advisor and co-author Chris Beard (KU Foundation Distinguished Professor and Senior Curator of Vertebrate Paleontology) discovered the Ecmomo, known in North America, from the Nadu Formation of the Baishi Basin in Guangxi, China. They collected fossils that closely resembled Wechashara materials. . By then, Ekumowechashala had become notoriously mysterious among North American paleontologists.
“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. “It didn’t take long and we had to do all kinds of detailed analysis. We knew what it was. We still have by far the best upper jaws in our collection here at KU. There are several important fossils, including one that is a molar.” “Ekumowechashala is known from North America. Its upper molars are very distinctive and look very similar to those in China. This proved to be a deal breaker because of the
Beard connected the Ekumowechashara and its cousins, the Chinese paleophodites, in a phylogenetic tree, and left Rust with the morphological analyzes to establish evolutionary relationships.
During the course of his research, Rust was able to draw conclusions about how Ekumowetshaala was discovered in Nebraska, millions of years after its fellow primates went extinct in the continent’s fossil record. is completed.
“We collected a significant amount of morphological data to create evolutionary trees using phylogenetic reconstruction software and algorithms,” Rust said. “This evolutionary genealogy suggests a close evolutionary relationship between the Ekumowechashala of North America and the paleophodites of China, which Chris and his colleagues discovered in the 1990s. The results of our analysis suggest that This clearly supports this hypothesis.”
University researchers say the discovery is not only exciting because it uncovers a new species of primate from late Eocene China, but also because it sheds light on the origin story of Ekmowetshashala. said. According to their research, Ekmowechashala was not a descendant of an older North American primate that somehow survived in colder, drier environments that wiped out other North American primates. Rather, their ancestors crossed the Belin region millions of years later, anticipating the route taken by the first Native Americans at a much later date.
“Our analysis dispels the idea that Ekumowechashala is a relic or survivor of early North American primates,” Rust said. “Rather, it was an introduced species that evolved in Asia and migrated to North America, probably via Beringia, during a surprisingly cool period.”
Species like Ekmowechashala, which suddenly appear in the fossil record long after their relatives have gone extinct, are called “Lazarus taxa,” after the Biblical figure who rose from the dead.
“In paleontology, the ‘Lazarus effect’ is when evidence of an apparently extinct animal is found in the fossil record, but after a long hiatus it reappears out of nowhere,” Professor Beard said. Told. “This is a grand pattern of evolution seen in the North American primate fossil record. The first primates came to North America at the beginning of the Eocene epoch, about 56 million years ago, and they continued to grow over more than 20 million years. They flourished on this continent. But about 34 million years ago, near the boundary between the Eocene and Oligocene periods, they became extinct as the climate became colder and drier. Millions of years later, Ekmowechashara appeared like a drifting gunslinger in a western movie, but it was just a flash.As far as the long evolutionary trajectory is concerned, Clovis With the arrival of humans in North America, the third chapter of primate life on this continent began. Like Ekmowetshashala, North American humans are a prime example of this. It’s the Lazarus effect.”
Rust and Beard were joined on this work by co-authors Xijun Ni of the Chinese Academy of Sciences in Beijing and scientific illustrator Kristen Tietjen of the KU Biodiversity Institute and Museum of Natural History.
According to Rust, the story of Ekumowechashala deserves people’s attention. That’s because this story takes place during a time of profound environmental and climate change, similar to ours, caused by human activity.
“It’s important to understand how past biota responded to such changes,” she says. “In such situations, organisms typically either retreat and adapt to more hospitable areas with available resources or face extinction. About 34 million years ago, all primates in North America North America lacked the conditions necessary for survival.” It emphasizes the importance of available resources. ”
This research is also part of a larger story, Rust said, representing an early chapter in our own evolutionary journey that ultimately led to our own species.
“Understanding this story is not only humbling, but also helps us understand the depth and complexity of the dynamic planet we live on,” she said. “This allows us to grasp the complex workings of nature, the evolutionary forces that give rise to life, and the influence of environmental factors.”