Ostrich-Like Dinosaurs in Ancient North America Grew to Enormous Sizes, Becoming One of the Largest in the World

A recent scientific study has uncovered new ornithomimosaur fossils from the Late Cretaceous Eutaw Formation in Mississippi. As per SciTech Daily, these ostrich-like dinosaurs were commonly referred to as "bird-mimic" dinosaurs and inhabited the ancient landmass of Appalachia in eastern North America.

The researchers identified two distinct species within the fossils: a small one and an exceptionally large one, weighing over 1,760 pounds (800 kilograms). These findings provide valuable insights into the little-known dinosaur ecosystems of eastern North America during the Late Cretaceous period and shed light on the evolution of ornithomimosaurs.

New Fossils of Ornithomimosaur Dinosaurs Found in Mississippi

In a recent study, titled "Large-Bodied Ornithomimosaurs Inhabited Appalachia During the Late Cretaceous of North America" published in the open-access journal PLOS ONE, it has been revealed that ostrich-like dinosaurs known as ornithomimosaurs attained enormous sizes in ancient eastern North America.

The North American continent was separated into two landmasses during the Late Cretaceous Period: Laramidia in the west and Appalachia in the east. However, the scarcity of fossils from the Appalachia region has resulted in a limited understanding of the ancient ecosystems that existed there.

Tsogtbaatar and colleagues have described newly discovered fossils of ornithomimosaurs from the Late Cretaceous Eutaw Formation in Mississippi to address this knowledge gap.

Ornithomimosaurs are also known as "bird-mimic" dinosaurs because of their superficial resemblance to ostriches, characterized by small heads, long arms, and robust legs. The newly found fossils, which include foot bones, are approximately 85 million years old, providing a rare glimpse into a poorly understood period of North American dinosaur evolution.

By analyzing the proportions of these fossils and examining growth patterns within the bones, the researchers concluded that the fossils likely belong to two distinct species of ornithomimosaurs-one relatively small and the other remarkably large. The 1,760-pound larger species is still undergoing growth at the time of its death. This discovery places it among the largest known ornithomimosaurs.

Ostrich-like Dinosaurs Cohabited With Other Species in the Late Cretaceous Period

The fossil record of Laramidia, a landmass during the Cretaceous period, contains numerous dinosaur specimens and a wide range of dinosaur species, Discover Magazine reported. However, in comparison, fossils from the Appalachian region are relatively scarce, leaving the extent of dinosaur diversity in this landmass largely unknown.

Researchers identified multiple species of ornithomimosaur dinosaurs that inhabited the Appalachian landmass simultaneously, with some of these species attaining significant sizes. These findings align with broader patterns observed in other dinosaur groups across North America and Asia. Nonetheless, further research is needed to fully understand the underlying reasons for these widespread patterns across the two continents.

The authors of the study emphasize that the presence of both medium- and large-bodied ornithomimosaur species during the Late Cretaceous Santonian epoch not only provides crucial information regarding the diversity and distribution of North American ornithomimosaurs in the Appalachian landmass but also suggests a broader occurrence of multiple cohabiting species of ornithomimosaurian dinosaurs in Late Cretaceous ecosystems across Laurasia.

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