MEANING: Horrible hand
PERIOD: Late Cretaceous
CONTINENT: Asia
Deinocheirus was an unusual ornithomimosaur. It was the largest of the clade at 12 m long, and weighing around 6 t. Though it was a bulky animal, it had many hollow bones which saved weight. The arms were among the largest of any bipedal dinosaur with large, blunt claws on its three-fingered hands. The legs were relatively short, and also bore blunt claws. Its vertebrae had tall neural spines that formed a "sail" along its back and the skull had a wide bill and a deep lower jaw, similar to those of hadrosaurs. For nearly half a century, the massive arms were all that was known of Deinocheirus, which led to some speculation and confusion among the paleontological community.
Deinocheirus 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.
Deinocheirus 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.