Discovery and namingEdit
The first known fossil remains are a single pair of massive forelimbs and the remains of some ribs and vertebrae. They were found on 9 July 1965 during a Polish-Mongolian expedition to the Gobi by Professor Zofia Kielan-Jaworowska at the Altan Ula III site in Ömnögovi Province. The find was reported by her in 1966. Deinocheirus was named by Halszka Osmólska and Ewa Roniewicz in 1970. The type species and only named species is Deinocheirus mirificus. The generic name is derived from Greek δεινός, deinos, "terrible", "horrible", and χείρ, cheir, "hand". The specific name is Latin for 'unusual', 'peculiar'.
The holotype specimen, ZPal MgD-I/6, was discovered on the desert surface in sandstone dating to the early Maastrichtian. It consists of a partial, disarticulated skeleton, most parts of which had already weathered away at the moment of discovery. Both forelimbs excluding the right claws, the complete shoulder girdle, centra of three dorsal vertebrae, five ribs, gastralia and two ceratobranchialia, supporting neck bones, could still be recovered. Additional fossils, including fragments of gastralia (belly ribs) belonging to the same specimen, were later found by teams re-examining the original fossil site. Some of these bones contained bite marks made by the contemporary tyrannosaurid species Tarbosaurus bataar, and showed evidence consistent with scavenging. The possibility that the carcass was scavenged by tyrannosaurs may explain why the specimen was preserved in a scattered, disassociated state. Two new specimens of Deinocheirus have been recently discovered and are awaiting publication. One specimen is larger even than the holotype, having a humerus 998 mm long. The other specimen is smaller, and the two together provide a nearly complete skeleton. The skull and foot bones were stolen by looters, but have recently been repatriated to Mongolia.