Kataigidodon venetus: New Cynodont Species Unearthed in Arizona
Paleontologists have uncovered a previously unknown species of cynodont that lived during the Triassic period in what is now Arizona, the United States.
They first appeared in the Late Permian period, approximately 260 million years ago, but diversified dramatically in the Triassic period.
They include the direct ancestors of mammals, and so might yield clues about how modern mammals came to be as successful as they are.
Scientifically named Kataigidodon venetus, the newly-identified cynodont species lived some 220 million years ago.
“This discovery sheds light on the geography and environment during the early evolution of mammals,” said lead author Ben Kligman, a doctoral student in the Department of Geosciences at Virginia Tech.
“It also adds to evidence that humid climates played an important role in the early evolution of mammals and their closest relatives.”
“Kataigidodon venetus was living alongside dinosauromorphs and possibly early dinosaurs related to Coelophysis, and the cynodont was possibly prey of these early dinosaurs and other predators like crocodylomorphs, small coyote-like quadrupedal predators related to living crocodiles.”
The two fossil lower jaws of Kataigidodon venetus were found in the Chinle Formation in the Petrified Forest National Park in Arizona.
“Finding a fossil that is part of Cynodontia, which includes close cousins of mammals as well as true mammals, from Triassic rocks is an extremely rare event in North America,” Kligman said.
Because only the lower jaws of Kataigidodon venetus were discovered and are quite small — 1.3 cm (0.5 inches), Kligman and colleagues only have a semi-picture of how the creature looked, roughly 9 cm (3.5 inches) in total body size, minus the tail.
Along with the jawbone fossils, they found incisor, canine, and complex-postcanine teeth, similar to modern day mammals.
“Given the pointed shape of its teeth and small body size, it likely fed on a diet of insects,” Kligman said.
About 220 million years ago, modern day Arizona and Texas were located close to the equator, near the center of the supercontinent Pangaea.
Kataigidodon venetus would have been living in a lush tropical forest ecosystem.
“It likely would have looked like a small rat or mouse,” Kligman said.
“If you were to see it in person you would think it is a mammal.”
A paper on the discovery was published in the journal Biology Letters.
Ben T. Kligman et al. 2020. A new non-mammalian eucynodont from the Chinle Formation (Triassic: Norian), and implications for the early Mesozoic equatorial cynodont record. Biol. Lett 16 (11): 20200631; doi: 10.1098/rsbl.2020.0631