Three extinct mammals found in Wyoming were part of the post-dinosaur revolution

Paleontologists have found a bed of ancient mammal bones amid the dry, brush-covered landscape of southern Wyoming. Three of these fossil finds belong to previously unknown species, and all of the animals at the site paint a different picture of mammal evolution following the demise of dinosaurs after a devastating asteroid strike 66 million ago. years.

The mammals at the site date back to the beginning of Puercan, that is, to the few hundred thousand years after the asteroid’s collision with Earth. The three new species are Miniconus jeanninae, Conacodon Hettingeri, and Beornus honeyi; all were in part named after the paleontologists who unearthed them, although the latter is also named after Beorn, a character from The Hobbit who can shape-turn into a bear. B. darling is the largest of the three new species, being about the size of a cat. The species were differentiated by their mandibles and teeth.

“Previous studies of North American mammalian faunas from the first ~ 320,000 years following the mass extinction event had found small mammals about the size of a rat to a mouse that were quite generalized in molar morphology. . This helped to understand that mammals still recovered and did not diversify quickly after the mass extinction, ”Madelaine Atteberry, paleontologist at the University of Colorado, said in an email. Atteberry is the principal author of a new study description of fossils, published in the Journal of Systematic Paleontology.

“However, the earliest Paleocene fauna in the Great Divide Basin in Wyoming, where our new mammal species originated, is another story,” Atteberry added. It has more diversity than we anticipate for this time period, which suggests that we can’t really generalize about mammalian recovery after dinosaur extinction. “

The fossil site was excavated by Jim Honey, Jeannine Honey and Malcolm McKenna between 2001 and 2011, after being mapped by Robert Hettinger of the U.S. Geological Investigation, whose name is attached to the recently described Conacodon Hettingeri. Now inundated Dry sandstone, the area was a floodplain during the time of these ancient mammals and was covered with intertwining streams and rivers. During the decade of work at the site, paleontologists have found more than 420 mammalian fossils. It is still unclear how so many fossils ended up in one place, although one of the team’s theories is that parts of the river would dislodge the sediment, trapping the animals (living and dead) that would eventually collapse. fossilize.

The three new finds are condylarthes, an ancient type of mammal whose descendants eventually produced modern ungulates: animals like camels, hippos, horses and rhinos. Atteberry said in a press release that the diversity of these new species shows how mammals have picked up on dinosaur extinction in stride, capitalizing on the absence of larger animals by developing new food sources and expanding into new environments.

It is likely that other species from the fossil deposits will be described – paleontologists have not yet had time to sort through the hundreds of bones that have been collected there. We even hope bigger ancient mammals, like it seems our first parents wasted no time getting bigger and bolder once their dinosaur lords have been taken care of.

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