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.
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.
DescriptionNothronychus 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.
In the Land Before Time