Deinocheirus

Deinocheirus is a genus of large ornithomimosaurian dinosaurs that lived in the Late Cretaceous period in what is now Mongolia. The name Deinocheirus, meaning "terrible hand," refers to its enormous claws, which were the first fossils discovered for this dinosaur. Initially, it was a poorly understood creature, with only these massive forelimbs and some ribs known. The extreme size and unusual anatomy of these fossils led to various speculative reconstructions over the years, including a giant theropod resembling a tyrannosaur or even a predatory dinosaur with a duck-like bill.

In 2014, the discovery of a more complete fossil, including a partial skeleton with a skull, arms, legs, and parts of the torso, revolutionized our understanding of Deinocheirus. This new evidence revealed a surprisingly different animal. Deinocheirus was a very large bipedal dinosaur, estimated to be up to 11 meters (36 feet) in length. It possessed a distinctive appearance with a large sail-like structure on its back, formed by elongated neural spines on its vertebrae, a relatively small skull with a broad, duck-like beak, and a long neck. Its arms, though large, were not primarily for predation but likely used for reaching vegetation or perhaps for display.

The diet of Deinocheirus is now understood to have been omnivorous, with evidence suggesting it consumed plants, fish, and possibly small animals. Its hindlimbs were robust and pillar-like, supporting its substantial weight. The discovery of Deinocheirus filled a significant gap in the evolutionary history of ornithomimosaurs, showing a remarkable divergence in size and form within this group of bird-like dinosaurs.