Nothronychus a North American therizinosaurid by Fred Bervoets
by Fred Bervoets
Two, possible four new dinosaurs discoverd in New Mexico
Two new dinosaur species have been unearthed in New Mexico, United States. One of the species (40 to 50 % complete) is a member of the theropod class of meat-eating dinosaurs that includes Tyrannosaurus and Allosaurus, but it apparently evolved into a plant-eater is named Nothronychus (sloth-like claw) and is of Cenomanian-Turonian, Late Cretaceous age.
Nothronychus belongs to a group of dinosaurs called therizinosaurs which are known from the Americas and China and Mongolia. According to paleontologists Jim Kirkland and Doug Wolfe, who announced the discovery, Nothronychus lived in a swampy forest similar to the bayous of Louisiana and weighed about a ton, was 4.5 to 6 mter (15 to 20 feet) long and stood 3 to 3.6 mter (10 to 12 feet) tall. The other species is a not yet been named coelurosaur.
Both fossils were dicovered about a half mile apart near New Mexico\\\'s border with Arizona in an area dubbed the Zuni Basin on the acient shores of the inland sea that once split North America. During this period sealevels were up 300 meter higher than today. Nothronychus was bipedal and walked more upright than its carnivore cousins, had a long, thin neck, long arms, dexterous hands, four-inch curved claws on its fingers, a large abdomen, a small head with a mouth full of leaf-shaped teeth designed for shredding vegetation, a relatively short tail and stout back legs.
The as yet unnamed coelurosaur was a bit more than 2.1 meter (7 feet) long and 0.91 meter (3 feet) tall. The scientists uncuvered 40 percent to 60 percent of a composite skeleton formed from two individuals.
According the paleontologist Kirkland possible two other new dinosaur species, an armored herbivore and a \\\"duck-billed\\\" plant-eater, both measuring about 20 feet in length, as well as a small mammal from the same site are being studied. Gillette and Albright described earlier another therizinosaurid from North America.
A nearly articulated, heavily encrusted therizinosaurid skeleton discovered in the Upper Cretaceous, late-early Turonian Tropic Shale of southern Utah, USA. This skeleton to date includes ribs, sacrum, paired right and left hindlimb elements (ilia, pubes, ischia, femora, tibiae, fibulae, astragali), seven metatarsals, ten pedal phalanges and fragments of others, caudal vertebrae, and chevrons.
The highly unusual opisthopubic pelvis, tetradactyl pes, and other synapomorphies indicate assignment to this family, but generic determination must await completion of the excavation. The tibia length (approximately 63 cm) is approximately 90% the femur length (approximately 70 cm), and metatarsal IV length (23 cm) is approximately 33% the femur length, proportions similar to those described for other therizinosaurs.