Ostrich-like dinosaurs from Mississippi are among the world’s largest at over 800 kilograms

Date:

Share post:

Ostrich-like dinosaurs called ornithomimosaurs grew to enormous sizes in ancient eastern North America, according to a study published in the open-access journal PLOS ONE by Chinzorig Tsogtbaatar of the North Carolina Museum of Natural Sciences and colleagues.

During the Late Cretaceous Period, North America was split by a seaway into two landmasses: Laramidia to the west and Appalachia to the east. But fossils from Appalachia are rare, and therefore ancient ecosystems from this region are poorly understood. In this study, Chinzorig and colleagues describe new fossils of ornithomimosaur dinosaurs from the Late Cretaceous Eutaw Formation of Mississippi.

Ornithomimosaurs, the so-called “bird-mimic” dinosaurs, were superficially ostrich-shaped with small heads, long arms, and strong legs. The new fossils, including foot bones, are around 85 million years old, making them a rare glimpse into a poorly known interval of North American dinosaur evolution

Paleohistological transverse sections of select elements of (A) large- and (B) medium-bodied individuals of the Eutaw ornithomimosaurs, and (C) relative body-size of the Eutaw ornithomimosaurs within known ornithomimosaur taxa through a geological time [Credit: Tsogtbaatar et al., 2022]

By comparing the proportions of these fossils and the patterns of growth within the bones, the authors determined that the fossils likely represent two different species of ornithomimosaurs, one relatively small and one very large. They estimate the larger species to have weighed over 800 kg, and the individual examined was likely still growing when it died. This makes it among the largest ornithomimosaurs known.

These fossils provide valuable insights into the otherwise poorly understood dinosaur ecosystems of Late Cretaceous eastern North America. They also shed light on ornithomimosaur evolution; giant body sizes and multiple species living side-by-side are recurring trends for these dinosaurs across North America and Asia. Further study will hopefully elucidate the reasons behind the success of these life strategies.

The authors add: “The co-existence of medium- and large-bodied ornithomimosaur taxa during the Late Cretaceous Santonian of North America does not only provide key information on 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.”

Source: Public Library of Science [October 19, 2022]

ADVERTISEMENT

spot_img

Related articles

Early land plant microfossils from the lower Silurian of southern Xinjiang, China

The Middle Ordovician-early Silurian is the key period for the origin and early evolution of morphological innovations of...

New old world vulture found from the Late Miocene of China

Neogene fossils of Old World vultures (Aegypiinae and Gypaetinae) are known from Africa, Eurasia, and North America. The...

Giant marine reptiles at 2,800 meters above sea level

More than 30 years ago, researchers from the University of Zurich discovered vertebrae, ribs and a tooth in...

‘A bad time to be alive’: Study links ocean deoxygenation to ancient die-off

In a new study, Stanford researchers have strongly bolstered the theory that a lack of oxygen in Earth's...

Australian fossil reveals new plant species

Antoine Champreux, a PhD student in the Global Ecology Lab at Flinders University, has catalogued the discovery of...

Blue colour tones in fossilized prehistoric feathers

Examining fossilised pigments, scientists from the University of Bristol have uncovered new insights into blue colour tones in...

Linyi Lagerstätte: A new window on Cambrian fauna evolution

A research team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS)...

Life on land and tropical overheating 250 million years ago

One of the key effects of the end-Permian mass extinction, 252 million years ago, was rapid heating of...