Ostrich-like dinosaurs, called ornithomimosaurs, grew to enormous sizes in ancient eastern North America, according to a study published Oct. 19, 2022 in the open-access journal. PLOS ONE by Chinzorig Tsogtbaatar of the North Carolina Museum of Natural Sciences and colleagues.
During the Late Cretaceous, North America was split into two landmasses by a seaway: Laramidia to the west and Appalachia to the east. But Appalachian fossils are rare, which is why ancient ecosystems from this region are poorly understood. In this study, Chinzorig and colleagues describe new fossils of ornithomimosaurus dinosaurs from the Late Cretaceous Eutaw Formation of Mississippi.
Ornithomimosaurs, the so-called “bird-mimicking” dinosaurs, were superficially ostrich-shaped with small heads, long arms and strong legs. The new fossils, including foot bones, are about 85 million years old, giving them a rare glimpse of a poorly known interval of North American dinosaur evolution.
By comparing the proportions of these fossils and the growth patterns in the bones, the authors determined that the fossils likely represent two different species of ornithomimosaurs, one relatively small and one very large. They estimate that the larger species weighed more than 800 kg, and the individual studied was probably still growing when it died. This makes it one of the largest known ornithomimosaurs.
These fossils provide valuable insights into the otherwise poorly understood dinosaur ecosystems of the late Cretaceous in eastern North America. They also shed light on the evolution of Ornithomimosaurus; gigantic body sizes and multiple coexisting species are recurring trends for these dinosaurs in North America and Asia. Further study will hopefully elucidate the reasons behind the success of these life strategies.
The authors add, “The coexistence of medium- and large-bodied ornithomimosaurs taxa during the Late Cretaceous Santonian of North America not only provides important information about the diversity and distribution of North American ornithomimosaurs from the Appalachian landmass, But it also suggests broader evidence of multiple cohabiting species of ornithomimosaurian dinosaurs in Late Cretaceous ecosystems of Laurasia.”
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Large ornithomimosaurs inhabited the Appalachians during the Late Cretaceous of North America, PLoS ONE (2022). DOI: 10.1371/journal.pone.0266648
Quote: Ostrich-like dinosaurs found in Mississippi are among the world’s largest ornithomimosaurs weighing more than 800 kg (2022, October 19) retrieved October 20, 2022 from https://phys.org/news/2022-10-ostrich-like -dinosaurs- mississippi-world-greatest.html
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