Niobrarasaurus

''Niobrarasaurus'' (meaning "Niobrara lizard") is an extinct genus of nodosaurid ankylosaur which lived during the Cretaceous 87 to 82 million years ago. Its fossils were found in the Smoky Hill Chalk Member of the Niobrara Formation, in western Kansas, which would have been near the middle of Western Interior Sea during the Late Cretaceous. It was a nodosaurid, an ankylosaur without a clubbed tail. It was closely related to ''Nodosaurus''.

The type species, ''Niobrarasaurus coleii'', was discovered and collected in 1930 by a geologist named Virgil Cole. It was originally described by Mehl in 1936 and named ''Hierosaurus coleii''. It was then re-described as a new genus by Carpenter ''et al.'' in 1995. In 2002 the type specimen was transferred to the Sternberg Museum of Natural History, Hays, Kansas. It has been estimated to be 5 meters (16 feet) in length and around 227–453 kg (500–1.000 lbs) according to Thomas Holtz. Paul gave a higher estimation of 6.5 meters (21.3 ft) and 4 tonnes (8.800 lbs).

Discovery and naming

The first remains of dinosaurs were discovered in the Niobrara Formation of Kansas by the excavations of American paleontologist Othniel Charles Marsh, who worked in the area from 1870 to 1872. The first of these dinosaur remains were collected and returned to the Yale Peabody Museum where they were named '' Hadrosaurus agilis'' by Marsh in 1872, before being given the generic name ''Claosaurus'' in 1890. An ankylosaur was then discovered in 1905 by Canadian paleontologist Charles H. Sternberg, though they were originally identified as the scutes of a turtle. These scutes, and additional material of the skeleton, were identified as the remains of an ankylosaur by American paleontologist George Wieland, who named them '' Hierosaurus sternbergii'' in 1909. The third discovery of dinosaurs in the Niobrara were found in the spring of 1930, where Virgil B. Cole excavated a large collection of bones and fragments, which were sent to the University of Missouri and accessioned as MU 650 VP. Cole wrote to American paleontologist Maurice Mehl about the finds on , where he described the discovery as a baby due to its small size. Many portions of the skeleton were articulated, and while most was weathered and broken into pieces, the ability to reassemble fragments led Mehl to believe that missing portions were scattered before burial.

The skeleton of MU 650 VP includes most of the skeleton and armor, with parts of the skull and teeth, vertebrae from the , , , and regions and their ribs, parts of the and , and bones from the and . It was discovered in Gove County, around south of Hackberry, Kansas, around above the base of the Niobrara Formation within the Smoky Hill Chalk Member. When originally described, Mehl considered the material to represent a new species of ankylosaur, giving it the name ''Hierosaurus coleii''. It was referred only tentatively to ''Hierosaurus'', as while there were both similarities and differences between the two species of the genus, until additional material of ankylosaur showing clearly that more than one genus was present within the Niobrara Formation, considering all ankylosaurs from to represent a single genus was advisable. Revisions of the ankylosaurs by American paleontologist Walter P. Coombs found ''Hierosaurus'' to be either an undiagnostic nodosaurid or a junior synonym of ''Nodosaurus'', with his 1971 thesis renaming ''H. coleii'' as "Nodosaurus coleii" as ''H. sternbergii'' was considered dubious, and his 1978 revision of ankylosaur families simply listing ''Hierosaurus'' as a synonym of ''Nodosaurus''. Coombs and Polish paleontologist Teresa Maryańska then considered ''Hierosaurus coleii'' to be a junior synonym of ''Nodosaurus textilis'' in 1990, with ''H. sternbergii'' as a dubious taxon. American paleontologist Kenneth Carpenter and colleagues reviewed ''Hierosaurus'' in 1995, finding the type species ''H. sternbergii'' to be a dubious taxon based on inadequate material. As ''H. coleii'' was diagnostic, and lacked any features unique to it and ''Nodosaurus'', Carpenter and colleagues named the new genus ''Niobrarasaurus'' for the species, with the genus named after the Niobrara Formation it was found in.

See also

* Timeline of ankylosaur research

References

* Carpenter, K. and Everhart, M. J. 2007. Skull of the ankylosaur ''Niobrarasaurus coleii'' (Ankylosauria: Nodosauridae) from the Smoky Hill Chalk (Coniacian) of western Kansas. Transactions of the Kansas Academy of Science, 110(1/2): 1-9
* Cole, V. B. 2007. Field notes regarding the 1930 discovery of the type specimen of ''Niobrarasaurus coleii'', Gove County, Kansas. Transactions of the Kansas Academy of Science 110(1/2): 132–134.
* Everhart, M. J. 2004. Notice of the transfer of the holotype specimen of ''Niobrarasaurus coleii'' (Ankylosauria; Nodosauridae) to the Sternberg Museum of Natural History. Transactions of the Kansas Academy of Science 107(3-4): 173–174.
* Everhart, M. J. and S. A. Hamm. 2005. A new nodosaur specimen (Dinosauria: Nodosauridae) from the Smoky Hill Chalk (Upper Cretaceous) of western Kansas. Transactions of the Kansas Academy of Science 108(1/2): 15–21.
* Liggett, G. A. 2005. A review of the dinosaurs from Kansas. Kansas Academy of Science. Transactions 108(1/2): 1–14.
* Mehl, M. G. 1931. Aquatic dinosaur from the Niobrara of western Kansas. Bulletin of the Geological Society of America 42: 326–327.

External links

''Niobrarasaurus''
from the Oceans of Kansas website

{{Taxonbar, from=Q137591

Nodosauridae
Dinosaur genera
Coniacian dinosaurs
Taxa named by Kenneth Carpenter
Taxa named by David B. Weishampel
Fossil taxa described in 1995
Dinosaurs of the United States