This is how the last animals in pre-human North America were able to survive on their own for so long

The last fauna to live in North America before humans arrived was A A tough cookie, as the Americans would say. By about 30 million years ago it had become colder and drier, no longer a good place for Egmovechasala. American and Chinese paleontologists are now learning more about why they lived in this mysterious isolation.

Based on fossilized teeth and jaws they found in both Nebraska and China. The researchers reconstructed evolutionary tree. The big reveal was a new Chinese sister species of Ecmovechashala, which they named Paleopodite, or ‘old wanderer’. This allowed the researchers to prove that Ecmovechashala was an immigrant and not the product of local evolution.

Unique solitude
Ekgmowechashala has been known to inhabit North America since the 1960s. “But because only its unique shape and teeth have been observed, its place in the evolutionary tree has long been debated,” says lead researcher Kathleen Rust. University of Kansas. “There was consensus on the classification as a primate, but the period to which the fossils were dated was very unusual.” Strangely, this animal appeared 4 million years after the extinction of all other animals in North America, which happened about 34 million years ago.

Normal tooth
Ekgmowechashala was a notorious enigma among American paleontologists for decades. It wasn’t until the 1990s that Professor Chris Beard found fossils in the Middle Formation in Guangxi, China, that resembled remains of Ecmovechashala from North America. “When we were there, we didn’t know we’d find an animal closely related to that strange animal from North America, but when I picked up the jaw and looked at it, I immediately thought: Wow, this is it,” explains Beard. . “It wasn’t like it took a lot of time or a lot of research, and we knew what it was. We have some very important fossils at the university, including the best-preserved molar from the upper jaw of Egmovechashala. It was very common and it was immediately obvious that it was like the molar we found in China.

On Beringlandbruck
Of course, that remains to be confirmed. An evolutionary family tree can be constructed using morphological data and phylogenetic reconstruction software. “This family tree shows that there was a close evolutionary relationship between Ecmovechashala from North America and paleopodites from China,” it said. This finally answers the question of how Ecmovechashala was able to survive on its own in North America. He’s not a descendant of an ancient North American animal that somehow managed to survive in a cold, dry climate while all of its peers went extinct. Instead, his ancestors came from China and managed to cross the Bering Land Bridge (the Bering Strait that now separates Siberia and Alaska) millions of years later. Native Americans Takes much later.

“Our analysis puts an end to the idea that Ecmovesachala was a survivor of earlier primates in North America,” Rust said. “Instead, it was a migrant that originated in Asia and moved to North America during a period of significant cooling, most likely via Beringia.”

Lazarus
Species such as Ecmovechashala, which suddenly appear in fossils long after their relatives have died out, are called Lazarus species after the biblical figure who rose from the dead. “The Lazarus effect in paleontology involves the discovery of fossils of animals that went extinct, but then appeared nowhere after a long time,” Beard explains.

“This is an evolutionary pattern that we often see in North American animal fossils. The first animals arrived in North America about 56 million years ago. They thrived on the continent for over 20 million years. But when it became colder and drier about 34 million years ago, they became extinct. Some Millions of years later, Egmovechashala suddenly appeared on the scene, albeit only relatively briefly. After Egmovechashala disappeared for more than 25 million years, the Clovis people reached North America, becoming the third episode of fauna on this continent. Like Egmovechashala, the first humans of North America are a textbook example of the Lazarus effect.

Climate change
Ekmovechashala’s story is still relevant today because, like those animals, we are in a period of great climate change. “It is important to know how previous species responded to such changes,” says the researcher. “In such situations, species typically adapt by retreating to more viable areas or becoming extinct. Around 34 million years ago, animals living in North America were unable to adapt because there were no viable conditions anywhere. This underscores the importance of available resources for our relatives to survive during severe climate change.