A very strange dinosaur has been uncovered, studied and explained by scientists. The dinosaur is from Mongolia about 70 million years ago.

“Deinocheirus is a totally bizarre dinosaur,” explains Phil Currie, professor and Canada Research Chair in Dinosaur Paleobiology at the University of Alberta. At 11 meters long and with an estimated weight of 6.4 tons, Deinocheirus was a behemoth to be sure—but hardly the giant tyrannosaur its massive arms may have suggested. Rather, the apparently disproportionately large forearms were more likely used for digging and gathering plants in freshwater habitats, or for fishing. Among its other unusual attributes are tall dorsal spines, truncated hoof-like claws on the feet to prevent sinking into muddy ground, and bulky hind legs that indicate it was a slow mover.

“Although the arms have been known since 1965 and have always aroused speculation because of their enormous size and sharp, recurving claws, we were completely unprepared for how strange this dinosaur looks,” says Currie. “It almost appears to be a chimera, with its ornithomimid-like arms, its tyrannosaurid-like legs, its Spinosaurus-like vertebral spines, its sauropod-like hips, and its hadrosaur-like duckbill and foot-hooves.”

Currie notes that Deinocheirus is a descendant of ostrich-like dinosaurs that were only slightly larger than humans, so its evolution into a giant, multi-tonne creature is almost certainly responsible for most of its unusual characteristics. “Its great size probably gave it some protection from the tyrannosaurid Tarbosaurus, which appears to have been relatively common in that part of Mongolia some 70 million years ago,” says Currie. To feed its great bulk, Deinocheirus was apparently an omnivore that ingested both plants and fish, as evident from fish remains found in its stomach contents.

“The study of this specimen has shown that even in dinosaurs like Deinocheirus, an animal that has been known for almost half a century, we can still learn surprising things about their anatomy,” says Currie. “Furthermore, it underlines the fact that even today, dinosaurs are still relatively poorly known. The fact that Deinocheirus is from the Nemegt Formation of Mongolia, one of the richest and most diverse dinosaur faunas known, hints that there are probably thousands of dinosaurs that we still do not know about from the majority of dinosaur localities in the world.”

Including poached dinosaur bones (stealing bones has long been a problem to the advancement of science) with the existing bones available to scientists allowed the new understanding of this amazing dinosaur. The now near-complete Deinocheirus specimen has been returned to its home for further study in the Mongolia Centre for Paleontology.

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