Nothronychus

*Nothronychus mckinleyi*

***Nothronychus*** (nahth-ROH-nye-KUSS) was a large member of the theropods known as the therizinosaurs. It lived during the Cretaceous Period around 91 million years ago in what is now the Southern United States.

## Discovery

In 2001, an expedition team led by Jim Kirkland and Doug Wolfe into the Zuni district in New Mexico revealed a new type of strange theropod dinosaur. They named it *Nothronychus* *mckinleyi*, after its huge, 1-foot (0.3-meter), sloth-like claws. The *mckinleyi* part of its name comes from Bobby McKinley, whose land is where this important find came from. A few years later another, a more complete specimen of *Nothronychus* was discovered in the Tropic Shale in Utah. *Nothronychus* is a significant find in the fossil record because it's the first evidence that therizinosaurs lived in North America, since all previous ones had been found in Asia.

## Description

   *Nothronychus* is built much like other therizinosaurs, like *Therizinosaurus*. It had a long neck to help it reach into the tops of trees and a small head to help pick out specific branches. It grew to be about 6 meters (20 feet) long, 3.4 meters (12 feet) tall, and one ton in weight. It had very long arms with long, impressive-looking sharp claws. Although these claws looked menacing, they were actually designed to get a grip on branches and bring them closer to the small head of this gluttonous herbivore. However, when threatened, they would make potentially deadly weapons. *Nothronychus* walked around on two thick, muscular hind legs, but it likely couldn't move fast. It had a short, but stocky tail that probably helped keep it balanced on its back legs. Most scientists also believe that *Nothronychus* and other therizinosaurs had downy feathers and potbellies, since they were herbivores. It may seem odd to think about, but *Nothronychus* and its relatives actually evolved from the raptor-like theropods, such as *Velociraptor*. Scientists aren't exactly sure when it occurred, but most speculate it was sometime during the early Cretaceous Period.

## JPInstitute.com Description

Nothronychus was a very strange looking plant-eater that evolved from a meat-eating dinosaur family. The discovery of Nothronychus has caused a lot of discussion among scientists. Before its discovery, this family of dinosaurs was known only from Asia.

It is closely related to Therizinosaurus, an Asian relative that was slightly larger. It may have had feathers as others in its family have been discovered with the remains of protofeathers in their fossils. This dinosaur has helped paint a picture of what life was like in the middle Cretaceous period in North America, a time period for which very few fossils have been discovered.

While the claws were very long, they were not very curved. In cross section they were also quite thin. One theory is that these claws were used to help it strip leaves from branches as well as being a formidable defensive weapon. Therizinosaurs had fairly long necks, small heads, and teeth that would have been used to eat plants.

## Links

http://web.archive.org/web/20040806083539fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_nothr.html
https://web.archive.org/web/20080705172048/http://kids.yahoo.com/dinosaurs/370--Nothronychus