Bactrosaurus

Taxobox
name = "Bactrosaurus"
fossil_range = Late Cretaceous


image_width = 250px
image_caption = "Bactrosaurus" skeleton.
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Ornithischia
subordo = Ornithopoda
infraordo = Iguanodontia
superfamilia = Hadrosauroidea
familia = Hadrosauridae
subfamilia = Lambeosaurinae
genus = "Bactrosaurus"
species = "B. johnsoni"
binomial = "Bactrosaurus johnsoni"
binomial_authority = Gilmore, 1933

"Bactrosaurus" (pronEng|ˌbæktrəˈsɔrəs) meaning "Bactrian lizard," "Bactria" + "sauros" = lizard)) was a herbivorous dinosaur that lived in east Asia during the late Cretaceous, 97 - 85 mya. The position "Bactrosaurus" occupies in the Cretaceous makes it one of the earliest known hadrosaurs, and although it is not known from a full skeleton, "Bactrosaurus" is one of the best known of these early hadrosaurs, making its discovery a significant finding."Bactrosaurus." In: Dodson, Peter & Britt, Brooks & Carpenter, Kenneth & Forster, Catherine A. & Gillette, David D. & Norell, Mark A. & Olshevsky, George & Parrish, J. Michael & Weishampel, David B. "The Age of Dinosaurs". Publications International, LTD. p. 131. ISBN 0-7853-0443-6.]

Description

A typical "Bactrosaurus" would have been 6 m (20 ft) long and 2 m (7 ft) high when in the quadrupedal stance, and weighed 1100 - 1500 kg (2400 - 3300 lb), with an 80 cm (31 in) femur. Like many hadrosaurs, it could switch between bipedal and quadrupedal stances,Fact|date=July 2008 but unusually it had large spines protruding from the vertebrae.Fact|date=July 2008

It was an early relative of "Lambeosaurus", and shows a number of iguanodont-like features, including three stacked teeth for each visible tooth, small maxillary teeth, and an unusually powerful build for a hadrosaur.

"Bactrosaurus" was originally described as lacking a crest, which would be typical for an iguanodont, but anomalously primitive for a lambeosaurine like itself. However subsequent study of "Bactrosaurus" remains uncovered pieces of what appear to be the base of an incompletely preserved crest.

In 2003, evidence of tumors, including hemangiomas, desmoplastic fibroma, metastatic cancer, and osteoblastoma was discovered in fossilized "Bactrosaurus" skeletons. Rothschild "et al." tested dinosaur vertebrae for tumors using computerized tomography and fluoroscope screening. Several other hadrosaurids, including "Brachylophosaurus", "Gilmoreosaurus", and "Edmontosaurus", also tested positive. Although more than 10,000 fossils were examined in this manner, the tumors were limited to "Bactrosaurus" and closely-related genera. The tumors may have been caused by environmental factors or genetic propensity.cite journal| last = Rothschild| first = B.M.| authorlink = | coauthors = Tanke, D.H., Helbling II, M. and Martin, L.D.| title = Epidemiologic study of tumors in dinosaurs| journal = Naturwissenschaften| volume = 90| issue = 11| pages = 495-500| publisher = | location = | date = 2003| url = http://www.springerlink.com/content/ktqqkxcqdc620keb/ | doi = 10.1007/s00114-003-0473-9| id = | accessdate = 2008-07-25]

Discovery

The first "Bactrosaurus" remains recovered from the Gobi Desert in China and Mongolia were comprised of partial skeletons of six individual "B. johnsoni". The specimens collected appear to come from a variety of age groups, from individuals that may be hatchlings to full-sized adults. The first of these was found in the same horizon as "Archaeornithomimus".Fact|date=July 2008

No complete remains have yet to be uncovered, but "Bactrosaurus" is still better known than most of the early hadrosaurs. Known parts of the anatomy of "Bactrosaurus" include the limbs, pelvis, and most of the skull (although the crest is notably absent).

ee also

Related animals
* "Gilmoreosaurus"Contemporaries
*"Archaeornithomimus"

References

External links

* [http://www.dinodictionary.com/dinos_b.asp DinoDictionary.com on "Bactrosaurus"]
* [http://www.trieboldpaleontology.com/casts/probactrosaurus_juvenile.htm Triebold Paleontology on "Bactrosaurus"]