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Paleontologists have discovered a previously unknown species of cynodont that lived during the Triassic period in what is now Arizona, in the United States.
The impression of an artist Kataigidodon venetus. Image credit: Ben Kligman / Hannah R. Kligman.
Cynodonts (clade Cynodontia), which literally means dog teeth, were one of the most diverse and successful groups of therapsids.
They first appeared in the late Permian, about 260 million years ago, but they diversified considerably in the Triassic period.
They include the direct ancestors of mammals and thus could provide clues as to how modern mammals have been as successful as they are.
Scientific name Kataigidodon venetus, the newly identified species cynodont lived about 220 million years ago.
“This discovery sheds light on geography and the environment during early mammalian evolution,” said lead author Ben Kligman, a doctoral student in Virginia Tech’s Department of Geosciences.
“It also adds to the evidence that humid climates played an important role in the early evolution of mammals and their closest relatives.”
“Kataigidodon venetus lived alongside dinosauromorphs and possibly the first dinosaurs related to Coelophysis, and the cynodon was likely prey to these early dinosaurs and other predators such as crocodiles, small quadrupedal coyote-like predators related to living crocodiles. “
The two lower jaws fossils 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 and true mammals, from the Triassic rocks is an extremely rare occurrence in North America,” Kligman said.
“Prior to this discovery, the only other unmistakable late Triassic fossil of western North America was the 1990 discovery of a cranium of Adelobasileus cromptoni in Texas “.
Because only the lower jaws of Kataigidodon venetus have been discovered and are quite small – 1.3 cm (0.5 in), Kligman and colleagues only have a half-image of what the creature looked like, about 9 cm (3.5 in) in total body size, minus tail.
Together with the jaw fossils, they found complex incisor, canine and post-canine teeth, similar to modern mammals.
“Given the pointed shape of his teeth and small body size, he probably ate a diet of insects,” Kligman said.
About 220 million years ago, modern Arizona and Texas were located near the equator, near the center of the supercontinent Pangea.
Kataigidodon venetus he would have lived in a lush tropical forest ecosystem.
“It probably would have looked like a little rat or mouse,” Kligman said.
“If you saw him in person, you’d think he’s a mammal.”
A paper on the discovery was published in the journal Biology letters.
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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
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