Creature of the Week #14: Nothronychus

marco_polo

Nothronychus (meaning "sloth-like claw) was a genus of dinosaurs that lived during the Mid Cretaceous aproximately 90 million years ago. A relatively recent discovery, the type species was discovered in 2001 in the Zuni Basin along New Mexico's border with Arizona.





Nothronychus has been classified in the group Therizinosauria, a visually striking group of herbivorous theropods renowned for their unusual combination of features including a beak, long neck, short tail, and long hand claws. Previously only known from discoveries in China and Mongolia, Nothronychus was the first therizinosaur to be discovered on the American continent.

A more primative relative dinosaur Falcarius utahensis (which was our creature F), was discovered in Utah in 2005. These discovers show that Therizinosauria belong firmly in the theropod group of dinosaurs which includes carnivorous dinosaurs like Tyrannosaurus and Allosarus, but the therizinosaurs later evolved into fully fledged plant-eaters.

Like all theorpods Nothronychus was bipedal but walked much more upright than its carnivore ancestors. Two species are currently known Nothronychus graffami , described in 2009, weighed about a tonne, was 4.5-6 m (15-20 ft) long and stood 3-3.6 m (10-12 ft) tall, while Nothronychus mckinleyi was only very slightly smaller.

The most distinctive features of Nothronychus are a small head with leaf-shaped teeth for shredding vegetation, and a long, thin neck. Nothronychus had a large abdomen, stout back legs and a relatively short tail. Like other therizinosaurs, Nothronychus had long arms with highly dexterous hands and 10 cm bent claws on each of its fingers. While no feathers were preserved other therizinosaur discovery indicate Nothronychus most likely also had a downy coat of feathers. Its preferred habitat was swampy forrests.


Short video clip from the series When Dinosaurs roamed America here

Some further reading:

http://www.azgs.state.az.us/Summer_07.pdf

Galvasean

For anyone interested we ran a story on Nothronychus here (other therizinosaurs discussed too).

Galvasean

Oh and if anyone is wondering who the cute little guy in the background is, that's Zuniceratops, a small relative of the more famous Triceratops. And by small, I mean the size of a Toyota Yarris. :P