Nothronychus

Artistic reconstruction of Nothronychus mckinleyi

• North America

• N. graffami Zanno and Others, 2009

Nothronychus is a dinosaur genus from the group of Therizinosauria. The species N. mckinleyi, was described in 2001 by James Kirkland and Douglas G. Wolfe according to findings in the Zuni Basin on the border between New Mexico and Arizona.

These findings are from rocks that belong to the " Morono Hill Formation", which on the early Late Cretaceous (middle Turonian ) be dated. A second, described as N. graffami 2009 copy was in the shale Tropical ( Tropic Shale ) formation found in Utah, which is dated to the early Turonian, between half and one million years before N. mckinleyi.

The name Nothronychus means as much as " lazy claw ".

Description

Nothronychus one of the Coelurosauria, the theropod group of carnivores, including the famous Tyrannosaurus heard. However Nothronychus is assigned to the subgroup of the Maniraptora. These theropods evolved into omnivores, and in the case of Nothronychus and his family even herbivores. He walked more upright on two legs as its carnivorous ancestors. N. graffami weighed about a ton, was 4.5 to 6 m long and 3 to 3.6 m high. N. mckinleyi was only a little smaller.

A reconstruction of 40 to 50 % of its skeleton, from two different species, allowed the scientists to describe its leaf-shaped teeth with rounded roots, a long neck, long arms with deft hands and 10 cm long, curved claws on his fingers, a large, big belly, stocky hind legs and a relatively short tail. N. mckinleyi differed from N. graffami is that it was built less robust, and in some details of the vertebrae and with a more curved forearm bones ( ulna )

Discovery and species

The first fossil that you were then assigned Nothronychus later discovered by a team of paleontologists in the Zuni Basin in New Mexico. A ilium ( hip bone ) of a Therizinosauriers was first identified erroneously as part of a newly discovered ceratopsian, the Zuniceratops. On closer inspection, then the true nature of the bone was found, however, and soon were also found more bones. Led by the paleontologist Jim Kirkland and Doug Wolfe team from New Mexico, published this Fund on August 22, 2001 in the Journal of Vertebrate Paleontology as a species Nothronychus mckinleyi. However, this name was already on 19 June 2001, in a column of RE Molnar published in the Arizona Republic.

A second, more fully preserved Therizinosaurier was found in 2000 by Merle Graffam, a resident of the city of Big Water in Arizona, in the shale Tropical ( Tropic Shale ) Formation of Utah. The area around Big Water was the target of several expeditions by teams of the Museum of Northern Arizona, as it was known for rich deposits of marine fossils, especially of plesiosaurs. In the late Cretaceous period was in this region, a shallow sea, the Western Interior Seaway, were obtained from the numerous marine reservoirs. The first discovery of Graffam (a large isolated aufgefundener toe bones ) surprised the scientists, because it was clear that it was a part of a terrestrial dinosaur, not a plesiosaur. The site had but have located some 100 kilometers from the Cretaceous shoreline. An excavation by a team from the Museum of Northern Arizona ( MNA) came across more parts of the skeleton against which the researchers realized that it was a Therizinosaurier. This was the first specimen of this dinosaur group that was found on the American continent. All previous Therizinosaurier fossils came from Mongolia and China.

The specimen found in Utah and examined by the team of MNA was, even though it has a more vigorous construction and is about half a million years older, found to be close relative of N. mckinleyi. This older specimen was first mentioned publicly in two rounds of talks on the occasion of the 54th meeting of the Rocky Mountain Geological Society of America, 2002. It was then referred to an issue of the online magazine Arizona Geology as one that differs from N. mckinleyi species, but not named. The species was named on July 15, 2009 by Lindsay Zanno and their colleagues in the journal Proceedings of the Royal Society B with respect to the discoverer Merle Graffam, as the new way Nothronychus graffami and classified. A reconstructed skeleton of N. graffami is exhibited in the Museum of Northern Arizona since September 2007.