When alive, Mexidracon would have been long-necked and long-legged as well as long-handed. It would also have been covered with a feathery coat. Credit: Ddinodan/Wikimedia Commons CC BY
A team of geologists, paleontologists, and climate scientists with members from institutions in Mexico, the U.S., and Spain has identified a new genus and species within the Ornithomimidae family. In their paper published in the journal Cretaceous Research, the group describes their study of the ancient ostrich-like dinosaur, and where it fits in with its family tree.
Ornithomimidae is a family of theropod dinosaurs, all of which bore some resemblance to the modern ostrich. Prior research has suggested that most were fast runners, were either herbivorous or omnivores, and existed during the Late Cretaceous Period of Laurasia, though some have reportedly been identified as being from the Lower Cretaceous Wonthaggi Formation of Australia. The researchers note that most members of the family also had small heads and long necks, forelimbs, and hindlimbs.
In 2014, a team of archaeologists and paleontologists were working at a dig site in Coahuila when they discovered the fossilized remains of a dinosaur that they were not able to identify. The remains were sent to Benemérita Escuela Normal de Coahuila, where they remained until the group on this new effort began a fresh examination.
The research team found that the remains belonged to a type of dinosaur that had not been seen before, though it was clearly a member of the Ornithomimidae family. The team was also able to show that it was from approximately 73 million years ago—they named it Mexidracon longimanus.
After conducting a phylogenetic analysis of the remains, the team was able to confirm that it was indeed a member of the Ornithomimidae family and that it formed a polytomic relationship with other members of its clade. They note that M. longimanus is clearly distinguishable from others in its family by its extremely long metacarpals, which meant it had long hands with a palm longer than its entire upper arm.
The researchers compare them to those sported by modern tree sloths, suggesting that their purpose was to allow the dinosaur to reach into shrubs, trees or bushes to pull branches or even twigs into their mouth. They also note that their hands would have been useful if the dinosaur preyed on small creatures that lived near the water’s edge.
More information:
Claudia Inés Serrano-Brañas et al, A long-handed new ornithomimid dinosaur from the Campanian (Upper Cretaceous) Cerro del Pueblo Formation, Coahuila, Mexico, Cretaceous Research (2025). DOI: 10.1016/j.cretres.2025.106087
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New genus and species within Ornithomimidae dinosaur family identified in Mexico (2025, February 3)
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