Mexidracon longimanus was an ornithomimid dinosaur that lived during the late Cretaceous, about 72 million years ago, in what is now northern Mexico.
It was a fairly small ornithomimid at around 2.5-3m long (~8-10′), and its leg proportions suggest it was less specialized for fast running than some of its other relatives. But its most unique feature was its hands, with extremely elongated metacarpal bones – giving it palms that were longer than its upper arm!
It’s unclear what the function of these unusual limbs was. Possibly they gave Mexidracon extra reach to hook its claws onto foliage and pull it within reach of its head, in a similar manner to ground sloths, chalicotheres, and therizinosaurs.
References:
- Nicholles, E. L. “Structure and function of the pectoral girdle and forelimb of Struthiomimus altus (Theropoda: Ornithomimidae).” Palaeontology 28 (1985): 619-628. https://www.palass.org/publications/palaeontology-journal/archive/28/4/article_pp643-677
- Serrano-Brañas, Claudia Inés, et al. “A long-handed new ornithomimid dinosaur from the Campanian (Upper Cretaceous) Cerro del Pueblo Formation, Coahuila, Mexico.” Cretaceous Research (2025): 106087. https://doi.org/10.1016/j.cretres.2025.106087
- Wikipedia contributors. “Mexidracon” Wikipedia, 05 Apr. 2025, https://en.wikipedia.org/wiki/Mexidracon
- Yirka, Bob. “New genus and species within Ornithomimidae dinosaur family identified in Mexico” Phys.org, 03 Feb. 2025, https://phys.org/news/2025-02-genus-species-ornithomimidae-dinosaur-family.html