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In northern Mexico, there are no modern primate species in North America. It was only when humans arrived on the coasts of the United States and Canada today that our taxonomic order was represented on most of the continent at the time modern.
Thus, when paleontologists working in Wyoming have recently unearthed the oldest fossil evidence of a primate ever discovered, this has been quite upsetting. Could primates have evolved in North America, migrated around the world, and then disappeared from their ancestral lands? Could the arrival of humans in North America have been able to represent, in a roundabout way, our order of taxonomy returning to us?
At the moment, this seems to be the case. The fossil itself belongs to a member of the genus Teilhardina, a group of tiny primates the size of an extremely abundant mice in the Paleocene-Eocene Thermal Maximum (PETM), a brief geologic period that has occurred. produced about 55 million years ago. They are widely regarded as the oldest common ancestor of all living primates.
North America was certainly part of the ancient Teilhardina range, which can also be found in Europe and Asia, but so far the oldest known Teilhardina came from Asia. So scientists have long assumed that genus, and therefore all primates, have appeared there.
It goes without saying that the latest discovery casts this theory out of the air, reports Phys.org.
"The scientific conclusion is that we simply do not know," said Paul Morse, the lead author of the study. "The fossils we have uncovered could upset past assumptions about the origin and migration of Teilhardina, but they certainly do not offer a clearer scenario."
The Wyoming specimen was dated using a combination of factors that included a careful study of the fossilized dentition of the genus and how that dentition had been transformed between different species. The most accurate dating mechanism, however, comes from the carbon signature of fossils, which can definitively place them on a timeline within PETM, the period they lived.
It also happens that the Wyoming site where the fossil was recovered, the Bighorn Basin, is probably also the best preserved site in the world, with its demarcated geological layers that are part of the PETM.
It is interesting to note that the PETM was a remarkable period in geological and climatic history, marked by an overall temperature of 8 degrees Celsius higher than today, caused by a rapid release of carbon into the atmosphere . This is comparable to the global warming period we are seeing today, except that the amount of carbon released during PETM was modest at 0.2 gigatonnes per year (at peaks of 0.58 gigatonne) , against 10 gigatonnes a year that are rejected by humans today. During PETM, the Earth became essentially ice-free and sea level increased 220 feet.
It is astounding to think that such a period of global warming could have created the environment that allowed our primate ancestors to evolve for the first time, and that global warming in modern times, on the other hand, threatens to threaten many species. Natural global warming could have brought us in, and unnatural anthropogenic global warming could be what makes us go out.
This is a lesson that little Teilhardina could inadvertently teach us about the unstable nature of biological systems and the fragility of their evolution. If these ancient primates represented a book end for our taxonomic order, hope that modern global warming will not be the other.
"A changing planet has dramatic effects on biology, ecosystems, and evolution, and is part of the process that has produced the diversity of life we see today and mass extinctions of life. that have occurred periodically in the history of the Earth, "said Jonathan Bloch, co-researcher. author. "One of the unexpected results of global warming 56 million years ago is that it was at the origin of the group that finally drove us in. The way we go about it will shoot in the future warming scenarios is less certain. "
In relation with MNN:
Primates may have evolved into … North America?
A surprising discovery in Wyoming radically changes our theories about the distant origins of our taxonomic order.
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