The last primate to live in North America before humans arrived was a tough cookie, as the Americans would say. About 30 million years ago it had become cold and dry, no longer a nice place for the Ekgmowechashala. American and Chinese paleontologists have now learned more about why this mysterious loner lived there.
Based on fossil teeth and jaws they found in both Nebraska and China, the researchers reconstructed the evolutionary tree. The big revelation was a new Chinese sister species of Ekgmowechashala, which they named Palaeophodite, or ‘old wanderer’. This allowed the researchers to demonstrate that Ekgmowechashala was an immigrant and not a product of local evolution.
Unique loner
The Ekgmowechashala has been known to live in North America since the 1960s. “But because of its unique shape and because only teeth were found, its place on the evolutionary tree was a subject of debate for a long time,” says lead researcher Kathleen Rust of the University of Kansas. “There was consensus toward its classification as a primate, but the period from which the fossils dated was quite unusual.” Strangely enough, the animal appeared more than 4 million years after all other primates in North America had gone extinct, which happened about 34 million years ago.
Typical tooth
The Ekgmowechashala was a notorious enigma among American paleontologists for decades. Until the 1990s, Professor Chris Beard found fossils in the Nadu Formation in Guangxi, China, that closely resembled the remains of the Ekgmowechashala from North America. “When we were there, we had no idea we would find an animal so closely related to that bizarre primate from North America, but when I picked up the jaw and looked at it, I immediately thought: wow, this is it ” explains Beard. “It’s not like it took a lot of time or a lot of research, we knew what it was. We have some crucial fossils here at the University, including by far the best preserved molar from the upper jaw of the Ekgmowechashala. And it is so typical and looked so much like the molar we found in China that it was immediately clear.”
Over the Beringlandbrug
Of course, that still had to be confirmed. An evolutionary family tree could be developed using morphological data and phylogenetic reconstruction software. “This family tree shows that there was a close evolutionary relationship between the North American Ekgmowechashala and the Palaeophodites from China,” it said. This finally answers the question of how the Ekgmowechashala managed to survive on its own in North America. He is not a descendant of an older North American primate, which somehow managed to survive in the colder, dry climate while its peers all went extinct. Instead, his ancestors came from China and millions of years later managed to cross the Bering Land Bridge (now the Bering Strait, which divides Siberia and Alaska), the same route as the Native Americans would also take much later.
“Our analysis puts an end to the idea that Ekgmowechashala is a survivor of earlier primates in North America,” Rust said. “Instead, it is an immigrant that originated in Asia and moved to North America during a noticeably cold period, most likely via Beringia.”
Lazarus
Species like Ekgmowechashala that suddenly appear in fossils long after their relatives have gone extinct are called Lazarus species, after the Biblical figure who rose from the dead. “The Lazarus effect in paleontology involves finding fossils of animals that went extinct, but then appear seemingly out of nowhere after a long absence,” Beard explains.
“This is an evolutionary pattern that we often see in the fossils of North American primates. The first primates came to North America about 56 million years ago. They thrived on the continent for more than 20 million years. But when it became colder and drier, about 34 million years ago, they became extinct. A few million years later, Ekgmowechashala suddenly appeared on the scene, albeit only for a relatively short time. After Ekgmowechashala had disappeared for more than 25 million years, the Clovis people reached North America, becoming the third chapter of primates on this continent. Like Ekgmowechashala, the first humans in North America were a textbook example of the Lazarus effect.”
Climate change
The story of Ekgmowechashala is still relevant today, because, like those primates, we are in a period of major climate change. “It is important to know how previous species responded to such shifts,” says the researcher. “In such situations, organisms normally adapt by retreating to more viable areas or becoming extinct. About 34 million years ago, primates in North America could not adapt because there were no habitable conditions anywhere. This underlines the importance of available resources for our relatives to survive during drastic climate change.”
