(CN) — Researchers at the University of Colorado in Boulder identified three new species of prehistoric mammals through fossils that enhance scientific understanding of how quickly mammals evolved after the extinction of the dinosaurs.
The bones of the creatures were part of the archive at the University of Colorado Museum of Natural History in Boulder. Unearthed in the Great Divide Basin by paleontologists and geologists beginning in the late 1990s, the collection waited years to be examined by experts.
The researchers published their findings Tuesday in the Journal of Systematic Paleontology.
Madelaine Atteberry, the lead author of the study, began examining the fossils as a project for her graduate program at the university. The research entailed comparing the fossilized teeth and jaws discovered in the Great Divide Basin to specimens already identified and collected at the museum.
“It was hours in front of a microscope comparing tooth to tooth and making measurements,” Atteberry said in an interview.
When it comes to identifying a new species, seemingly minute details like the height of one molar or the number of cusps on another can help lead researchers to a discovery. Eventually, this intensive review of the fossils resulted in the identification of the three new prehistoric mammal species of prehistoric mammals, each with a unique set of dental features.
Atteberry said she named the largest of the newly discovered species Beornus honeyi after Beorn, a character in J.R.R. Tolkien’s “The Hobbit.” Atteberry said the character “is known for his very large size among regular-sized people.” The species Beornus honeyi was approximately the size of a modern housecat — not the largest mammal ever discovered from this time period, but larger than many of the mouse and rat-sized mammal species already known to scientists.
“Compared to the other very small animals that were living at the time, this guy was pretty big,” Atteberry said.
The researchers are interested in what the size of the Beornus honeyi and the discovery of all three new species suggest about the period immediately after the non-avian dinosaurs were wiped out 66 million years ago.
Though mammals co-existed with the dinosaurs, the mammals that survived the mass extinction and lived for the subsequent few hundred thousand years in the western interior of North America were generally thought to be lacking in diversity.
“What we’re finding in the Great Divide Basin is that’s not entirely the story,” said Jaelyn Eberle, a vertebrate paleontologist and professor of geologic studies who co-wrote the study. “There were more kinds of mammals appearing on the scene shortly after the dinosaurs went extinct than we initially thought.”
Atteberry and Eberle said there is much more to be learned about the ecology that allowed prehistoric mammals to diversify faster than previously estimated.
“There’s certainly more to be discovered about this locality, and from there, more to be learned about this period of time in general in the western interior of North America,” said Atteberry.
Eberle agreed. “Some of the interesting new work that I look forward to… is figuring out how [the species] were operating in the earliest Paleocene, in this world that’s devoid of non-avian dinosaurs. We’re not entirely sure what they were doing, how they were living in their environment, what they were feeding on. There’s a lot of unanswered questions, but that’s the fun part of this.”
The collection Atteberry and Eberle used contains more than 400 fossils from the Great Divide Basin, some of which have not yet been identified. They think there are likely more new species to be discovered that can help piece together the puzzle.
“It’s cool to me that the story of the earliest Paleocene mammals is far from complete,” said Eberle. “I really predict that there are more new species hiding out in this collection that we just haven’t had a chance to look at yet, so if anything, we’re just at the tip of the iceberg.”
Eberle also thinks other scientists could have opportunities to discover new species as well using museum archives.
“Many museums have been collecting for decades, over a century in many cases,” said Eberle. “There’s a lot to be discovered by scientists studying materials that are within natural history collections. This is a prime example of what could be in your collection.”
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