An unknown species of dinosaur that populated American territory 66 to 68 million years ago has been described by American and Canadian paleontologists.
Eoneophron infernalis belongs to the family Caenagnathidae, theropod dinosaurs that closely resembled birds and lived in North America and Asia during the Late Cretaceous.
Eoneophron was estimated to have weighed about 73 kg (160 pounds) and stood about 1 meter (3 feet) tall at the hip.
Its fossilized remains were collected from outcrops of the Hell Creek Formation in South Dakota in 2014, but they were assigned to a different species.
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Eoneophron infernalis (top left), Anzu wyliei (right) and another caenagnathid dinosaur (bottom left) in the Hell Creek Formation. (Artistic illustration)
Photo: Oklahoma State University/Zubin Erik Dutta
Oklahoma State University (OSU) paleontologist Kyle Atkins-Weltman examined a small collection of bone fossils that he believes belonged to a juvenile Anzu wyliei.
The expert in vertebrate anatomy was not interested in identifying a new species. Instead, he tried to understand how Anzu's metatarsals or toe bones supported her weight.
Fossils suggested the animal was about 25% smaller than other Anzu remains. So we thought it was a juvenile Anzu. And that's what we thought until evidence showed that wasn't the case.
When he realized the fossils might not belong to Anzu, the paleontologist turned to caenagnathid experts Greg Funston of the Royal Ontario Museum and Jade Simons of the University of Toronto for help and expertise.
The researcher also reached out to Holly Woodward Ballard, a professor of anatomy at OSU, whose research is based on paleohistology, the study of fossil bone microstructures.
Thanks to newer techniques, they were able to determine that the bones of the foot and leg were structurally similar not to those of a young Anzu wyliei, but to those of a more mature specimen that could only belong to a dinosaur species unknown to science.
It was really exciting. I never thought that one day I would discover a new species of dinosaur.
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A femur of Eoneophron infernalis.
Photo: Oklahoma State University/Kyle Atkins-Weltman
This dinosaur was covered in feathers and had relatively short wings and tail. Its toothless beak makes it difficult to determine its diet, says Kyle Atkins-Weltman, lead author of the paper published in the journal PLoS ONE (New Window).
The chicken from hell
Kyle Atkins-Weltman named the new dinosaur Eoneophron infernalis, which translates to “Hell Chicken from the Pharaoh's Dawn.” This name refers to the description of the Anzu as well as his deceased beloved pet, a Nile monitor lizard named Pharaoh.
To date, paleontologists have discovered three species of caenagnathids of varying sizes that lived in the ecosystems of the Hell Creek Formation. Atkins-Weltman said this diversity supports the idea that these species were not in decline at the end of the Cretaceous.
Canadian scientists from the University of Toronto and the Royal Ontario Museum were also involved in the work.