A study, led by Chinzorig Tsogtbaatar of the North Carolina Museum of Natural Sciences and colleagues, shows that ostrich-like dinosaurs called ornithomimosaurs grew to spectacular size in ancient eastern North America during the Late Cretaceous, about 85 million years.
The creature would have weighed more than 800 kilos and would have moved through what is now Mississippi, United States. And it is known that some of the largest dinosaurs that existed on the planet, stomped on the current Mississippi.
North America was home to great dinosaurs
During the Late Cretaceous, what was North America was separated into two landmasses by the ocean. To the west, we had Laramidia , while to the east was Appalachia, which is where these nearly one-ton giant ostriches once lived.
“Continental separation had appreciable consequences for the evolution of North American dinosaurs, with distinct lineages evolving in isolation on each land mass. Although the Appalachian vertebrate fossil record suggests a distinct and diverse fauna, most part of this record is based on relatively poorly preserved and often isolated specimens, compared to the more extensive record of Laramidian species,” the authors explain in their paper published in the journal PloS One.
The recovered ornithomimosaur specimens were studied by a research team led by Chinzorig Tsogtbaatar of the North Carolina Museum of Natural Science and discovered in the Santonian Eutaw Formation of Mississippi.
One of the largest ornithomimosaurs known
By comparing the proportions of these fossils and the growth patterns within the bones, paleontologists determined that the fossils likely represent two different species of ornithomimosaurs , one relatively small and one very large.
“Ornithomimosaurs, the so-called bird-mimicking dinosaurs, were superficially ostrich-shaped with small heads, long arms and strong legs,” the experts clarify. “The new fossils, including the leg bones, are about 85 million years old, making them a rare glimpse into a poorly understood interval of North American dinosaur evolution .”
The fossils “suggest the presence of two taxa of different body sizes, including one of the largest ornithomimosaurs known anywhere in the world” .
The researchers hope to further investigate why such different animals adapted so well to their shared environment. And it is that, these species that cohabited were of very different sizes and some were very, very large.
“The coexistence of medium- and large-bodied ornithomimosaur taxa during the Santonian of Late Cretaceous North America not only suggests broader evidence for multiple species of ornithomimosaur dinosaurs co-inhabiting Late Cretaceous Laurasian ecosystems, but also provides key information on the diversity and distribution of North American ornithomimosaurs from the Appalachian landmass,” the scientists said.
Referencia: C. Tsogtbaatar et al. 2022. Large-bodied ornithomimosaurs inhabited Appalachia during the Late Cretaceous of North America. PLoS ONE 17 (10)