MEANING: Mexican dragon
PERIOD: Late Cretaceous
CONTINENT: North America
Mexidracon is a relatively small ornithomimid theropod dinosaur at approximately 2.5 m in length. Typical of ornithomimids, it was likely covered in feathers, and had a long neck and legs. Mexidracon is notable for its extremely lengthened metacarpals, or hand bones, not seen in other ornithomimids.
Abstract from paper: New ornithomimosaur material discovered from the Upper Cretaceous Cerro del Pueblo Formation (CdP) of Coahuila, Mexico represents a new genus and species of Ornithomimidae. The new taxon, Mexidracon longimanus sp. nov., is represented by an individual preserving axial and appendicular elements. M. longimanus is characterised by the following combination of characters: extreme lengthening of the metacarpals that are longer than the metatarsals, proximal end of metacarpal II with a narrow subtriangular outline, a pubic peduncle of the ilium with a flared, zig-zag articular margin that is wider anteriorly than posteriorly and an ischiadic peduncle that is similar in size to the pubic peduncle, a pubic boot where the distal margin of the anterior expansion is separated from the shaft by a deep notch, a femur that is slightly longer than the tibia, an arctometatarsalian pes, a metatarsal II that has a D-shaped cross-section, and a metatarsal IV longer than metatarsal II, among other features. A phylogenetic analysis places M. longimanus within Ornithomimidae forming a polytomic relationship with other members of this clade. The finding of M. longimanus adds to the increasing diversity and paleobiogeographic distribution of the group during the Campanian of southern Laramidia. The ornithomimosaur record of the CdP represents yet another instance of the coexistence of ornithomimids and deinocheirids spanning a wide range of body sizes within this clade of ‘ostrich’ dinosaurs.
Mexidracon is from the Cretaceous. The Cretaceous is a geological period that lasted from about 145 to 66 million years ago. It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period.
The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct flora and fauna, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth by the end of the Cretaceous, coincident with the decline and extinction of previously widespread gymnosperm groups.
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary (K–Pg boundary), a geologic signature associated with the mass extinction that lies between the Mesozoic and Cenozoic Eras.
Mexidracon is an ornithomimosaur. Ornithomimosaurs are omnivorous theropods from the Cretaceous Period. They mostly resemble modern-day ostriches, as fast runners with long legs and long necks. However, this group also contains the Deinocheirids, which were much bulkier and more robust. The group first appeared in the Early Cretaceous and persisted until the end of Late Cretaceous.
The skulls of ornithomimosaurs were mostly small, with large eyes, above relatively long and slender necks. The most basal members had a jaw with small teeth, while the later and more derived species had a toothless beak. The arms were long with powerful claws. Evidence of feathers is known from some specimens, and ornithomimosaurs are mostly speculated to have been covered in ostrich-like plumage.