Nothronychus

Filed under Cretaceous dinosaurs · Types of Dinosaurs editorial team

Order: Saurischia · Suborder: Theropoda · Infraorder: Therizinosauria · Family: Therizinosauridae

Nothronychus, whose name translates to "slothful claw," was a large therizinosaur that lived during the Late Cretaceous period in what is now North America. Reaching an estimated 15 to 20 feet in length, it belonged to the family Therizinosauridae — a group of dinosaurs long known primarily from Asia. Its discovery was therefore significant, confirming that therizinosaurs had spread far beyond their Asian origins and establishing Nothronychus as one of the first members of this peculiar lineage found on the North American continent.

Despite being a theropod — a group that includes many well-known predators — Nothronychus was entirely herbivorous. Its body was pot-bellied and broad, built to house the lengthy digestive system typical of plant-eaters. A long neck supported a small head equipped with leaf-shaped teeth suited to processing vegetation, while its large hands bore long, prominent claws that were most likely used to draw branches and foliage toward its mouth rather than for any predatory purpose.

Slow-moving and distinctive in appearance, Nothronychus offered paleontologists a clearer picture of how profoundly therizinosaurs had diverged from the carnivorous lifestyle ancestral to theropods. Its anatomy stands as a striking example of how dramatically dinosaur body plans could shift in adaptation to different ecological roles.

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Reference background: Natural History Museum, London — Dinosaurs; Smithsonian National Museum of Natural History — Dinosaurs; American Museum of Natural History — Dinosaurs & Fossils. Figures are typical published ranges; taxonomy follows the source era and modern consensus is noted where it differs. See our sources & fact-check policy.

Related dinosaurs

Other dinosaurs from the Therizinosauridae family.