Deinocheirus mirificus

Deinocheirus mirificus, a genus of large ornithomimosaurian theropod dinosaurs from the Late Cretaceous period approximately 70 million years ago, was first discovered in Mongolia’s Nemegt Formation in 1965, initially known only from its massive forelimbs measuring about 2.4 meters in length, leading to its name meaning “terrible hand”; however, subsequent discoveries revealed a more complete picture of this unique dinosaur, which measured over 10 meters in length and weighed around 6.5 tonnes, featuring a combination of distinctive characteristics such as a long, toothless skull with a duck-like beak, a sail-like structure formed by elongated neural spines on its back, and large, blunt claws on its forelimbs, suggesting adaptations for omnivorous feeding habits that included both plant material and fish, as evidenced by gastroliths and fish remains found in association with its fossils, positioning Deinocheirus as a highly specialized member of the ornithomimosaur clade, with a body plan and ecological niche that distinguish it from other theropods of its time; the discovery of more complete specimens in the early 2010s, including two individuals that had been partially collected by fossil poachers but later recovered and studied by scientists, provided significant insights into the anatomy and ecology of Deinocheirus, revealing that it possessed a unique combination of features not seen in other dinosaurs, such as a large, humped back supported by tall neural spines, a broad, duck-like bill, and a bulky body supported by relatively short, robust legs, indicating that, unlike other ornithomimosaurs which were built for speed, Deinocheirus was not adapted for fast running, and its physical characteristics suggest it led a different lifestyle, possibly foraging in aquatic environments for a variety of food sources; the presence of gastroliths—stones swallowed to aid digestion—along with fish remains in the stomach region of one specimen, indicates that Deinocheirus had an omnivorous diet, consuming both plants and animals, which is further supported by the structure of its beak and jaws, adapted for cropping vegetation and possibly foraging in water; the discovery of Deinocheirus has significantly expanded our understanding of the diversity and ecological roles of theropod dinosaurs, demonstrating that they occupied a wider range of niches than previously thought, and highlighting the complex evolutionary history of this group during the Late Cretaceous period.