The strange fate of Ekgmowechashala, the last of the American apes
The primate populated North America long before the arrival of Homo sapiens.
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Ekgmowechashala, the last primate to populate North America before humans. (Artistic illustration)
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The very existence of Ekgmowechashala was rather enigmatic. Paleontologists knew that the small, very singular animal weighing around 2 kg and looking like a lemur had been the last monkey to populate the territory corresponding to today's American Great Plains, but the evolution of the species remained poorly understood. Its place among primates has even been debated.
Due to its unique morphology and the fact that it is represented only by dental remains, its place in mammalian evolution has been the subject of debate, but consensus has leaning in favor of its classification as a primate, explains in a press release paleontologist Kathleen Rust, of the Biodiversity Institute at the University of Kansas, and lead author of the work published in theJournal of Human Evolution(New window) (in English).
The first North American primates appeared about 56 million years ago and thrived on the continent for more than 20 million years. They then all disappeared 34 million years ago, when the planet became colder and drier, making the continent inhospitable to these usually heat-loving animals.
Or, Ekgmowechashalaappears in the fossil record of the Great Plains more than 4 million years after the extinction of all other North American ape species.
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Fossilized teeth of Ekgmowechashala
To try to understand what may seem like an anomaly, the Chinese-American team of paleontologists wanted to reconstruct the family tree ofEkgmowechashala. To do this, Kathleen Rust and her colleagues from the University of Kansas and the Beijing Institute of Vertebrate Paleontology analyzed fossilized teeth and jaws unearthed in Nebraska in the 1960s and other eerily similar fossils discovered in the 1990s in the Guangxi region of China.
We assembled a large body of morphological data to create an evolutionary tree that shows a close relationship between Ekgmowechashala from North America and fossils from China.
A quote from Kathleen Rust, University of Kansas
Thus, according to paleontologists, the presence of Ekgmowechashala in North America would not be the result of the evolution of an older primate that adapted to the cooler, drier conditions that led to the extinction of other primates on the continent.
According to Kathleen Rust, the ancestors ofEkgmowechashala would rather have come from a species that arrived from Asia via the Bering Strait millions of years later, according to certain scenarios similar to that of the arrival of the first humans.
In addition, the simultaneous presence ofEkgmowechashalain Oregon and the Great Plains indicates that the last nonhuman primates became extinct in North America about 26 million years ago, the study authors note.
Species like Ekgmowechashala, which suddenly appear in the fossil record long after their parents have disappeared, are called Lazarus taxa, in reference to the character biblical who was raised from the dead by Jesus.
Following the disappearance ofEkgmowechashala, no primate species populated the North American continent for more than 25 million years, until the arrival of the first Homo sapiens.
The arrival of humans in North America marked the third chapter in the history of primates on this continent. Like Ekgmowechashala, humans in North America are a prime example of the Lazarus Effect.
A quote from Chris Beard, professor emeritus at the University of Kansas
Paleontologist Kathleen Rust believes that the history ofEkgmowechashala deserves to be told because it took place in an era marked by profound environmental and climatic changes, like ours, due to ;human activity.
It is essential to understand how extinct species responded to such changes. In such situations, organisms usually adapt by retreating to more hospitable regions with resources, or they face extinction.
A quote from Kathleen Rust, University of Kansas< /blockquote>
This is precisely what happened about 34 million years ago, when all North American primate species were unable to adapt to survive. /p>
North America did not have the conditions necessary for their survival. This highlights the importance of resource accessibility for our non-human primate relatives (bonobos, chimpanzees and gorillas) in times of radical climate change, adds Kathleen Rust.
Understanding this narrative not only humbles us, but also helps us appreciate the depth and complexity of the dynamic planet we inhabit.
A quote by Kathleen Rust, University of Kansas
It allows us to grasp the complex workings of nature, the power of evolution in evolution ;appearance of life and the influence of environmental factors, notes the American paleontologist.