An international team of paleontologists has found a specimen of a previously unknown species of mammal from the early Paleocene, about 65 million years ago.
An artistic life reconstruction of Kimbetopsalis simmonsae. Image credit: Thomas E. Williamson et al / Unsplash / Sci-News.com.
The newly discovered mammal, Kimbetopsalis simmonsae, comes from fossil-rich beds of the Nacimiento Formation, New Mexico.
According to the UK and American paleontologists who studied this new mammal, it was a member of a group of extinct small, furry mammals called the multituberculates.
These rodent-like creatures, which originated some 100 million years before the dinosaurs were killed off, were distinctive in having strange and complex teeth (‘multituberculate’ refers to the multiple rows of cusps found on the animals’ teeth). Their sharp incisors and molars with lots of cusps were suited to their diet of plants and leaves.
The group survived the events that led to the demise of dinosaurs, and spread through what is now Asia and North America.
These mammals finally died out about 35 million years ago, when they were replaced by emerging rodents.
Kimbetopsalis simmonsae was about the size of a beaver and may have been an evolutionary ancestor of the bigger-sized multituberculate mammal Taeniolabis taoensis (weighed up to 100 kg).
The species description was published in the Zoological Journal of the Linnean Society by Dr Thomas Williamson of the New Mexico Museum of Natural History and Science and co-authors.
The Kimbetopsalis simmonsae teeth found by the team included incisors (left) and molars (right). Image credit: Thomas E. Williamson et al.
“Finding this new mammal was a pleasant surprise,” Dr Williamson said.
“It helps fill an important gap in the record of this group of mammals. It’s interesting that this odd, now extinct group, was among the few to survive the mass extinction and thrive in the aftermath. It may be because they were among the few mammals that were already well-suited to eating plants when the extinction came,” he said.
“This new species helps to show just how fast they were evolving to take advantage of conditions in the post-extinction world.”
“We could think of Kimbetopsalis simmonsae as a primeval beaver, which lived only a few hundred thousand years after the asteroid impact that killed the dinosaurs,” said co-author Dr Steve Brusatte of the University of Edinburgh, UK.
“The asteroid caused apocalyptic environmental change, but it seems like mammals began to recover pretty quickly afterwards.”
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Thomas E. Williamson et al. A new taeniolabidoid multituberculate (Mammalia) from the middle Puercan of the Nacimiento Formation, New Mexico, and a revision of taeniolabidoid systematics and phylogeny. Zoological Journal of the Linnean Society, published online October 5, 2015; doi: 10.1111/zoj.12336
