A long-handed new ornithomimid dinosaur from the Campanian (Upper Cretaceous) Cerro del Pueblo Formation, Coahuila, Mexico

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.