Deinocheirus

What it was like

Deinocheirus was a huge, bulky ornithomimosaur with a wide, flattened bill somewhat like that of a duck-billed dinosaur, and tall spines along its back that likely formed a hump or sail. It grew to about 11 meters (36 feet) long and weighed around 6,400 kilograms (about 7 short tons), making it by far the largest animal in its family.

Its arms were unusually long and ended in blunt claws, though its legs were short for its size. Paleontologists think it ate both plants and animals: its bill suggests it fed on soft vegetation, while fish remains found with one skeleton suggest it also caught prey near water.

Its world

Deinocheirus lived about 72 to 66 million years ago, in the Late Cretaceous, in what is now Mongolia. Its fossils come from the Nemegt Formation.

It shared this floodplain habitat with the clawed Therizinosaurus, the predator Tarbosaurus, the small Alioramus, the plant eater Saurolophus, the long-necked Opisthocoelicaudia, and the small-armed Mononykus and Adasaurus.

How it was found

Kielan-Jaworowska named Deinocheirus in 1969, based only on a pair of huge arms and shoulder bones. For decades, no other remains turned up, and its full body shape stayed a mystery. Since then, paleontologists have recovered about four fossil finds, including more complete skeletons that finally showed what the rest of the animal looked like. It is considered a close relative of the smaller Garudimimus.