Nothronychus

Nothronychus is an unusual herbivorous theropod from the Late Cretaceous of New Mexico and Utah. Before its description in 2001, therizinosauroids were known almost exclusively from Asian fossil beds. Measuring roughly five metres in length and tipping the scales at around a tonne, this pot-bellied giant resembled an oversized ground sloth. It possessed a small skull with peg-like teeth, a long, flexible neck, and stocky hind limbs designed for supporting bulk rather than speed. Its most iconic features were the massive, curved sickle claws on its three-fingered hands, which reached up to thirty centimetres in length. Rather than using these talons to kill prey, Nothronychus employed them like grappling hooks to draw foliage-rich tree branches down to its mouth, and possibly to deter terrestrial predators like tyrannosauroids.

It was the first well-preserved therizinosaurid discovered in the Americas, confirming their presence outside Asia.

Where and when

Nothronychus lived in the Late Cretaceous, from 93.9 to 91 million years ago (Turonian age). Its remains come from United States, in the Moreno Hill Formation.

The numbers

Length 4.9 m (estimates run from 4.5 to 5.3 m). Mass about 980 kg. Hip height about 2 m. That is 2.9 human-lengths, or 0.44 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Nothronychus with a bus Place on the timeline