Bactrosaurus
{{Short description|Extinct genus of dinosaurs}}
{{Automatic taxobox
| fossil_range = Late Cretaceous (Cenomanian – Santonian) {{fossilrange|96|85}}
| image = Smuggled Bactrosaurus skeleton.jpg
| image_caption = Skeleton on display at the Central Museum of Mongolian Dinosaurs, Ulaanbaatar
| taxon = Bactrosaurus
| authority = Gilmore, 1933
| type_species = {{extinct}}Bactrosaurus johnsoni
| type_species_authority = Gilmore, 1933
| subdivision_ranks = Other species
| subdivision =
| synonyms =
- "Bakesaurus" Zhou, 2005 (nomen nudum)
- Cionodon kysylkumensis? Riabinin, 1931
}}
Bactrosaurus ({{IPAc-en|ˌ|b|æ|k|t|r|ə|ˈ|s|ɔːr|ə|s}}; meaning "Club lizard," "baktron" = club + sauros = lizard) is a genus of herbivorous hadrosauroid dinosaur that lived in Asia during the Late Cretaceous, from about 96 to 85 million years ago. The position Bactrosaurus occupies in the Cretaceous makes it one of the earliest known hadrosauroids, and although it is not known from a full skeleton, Bactrosaurus is one of the best known of these early hadrosauroids, making its discovery a significant finding.
Discovery
The first Bactrosaurus remains recovered from the Iren Dabasu Formation in the Gobi Desert of China were composed 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 fossils were described in 1933 by Charles W. Gilmore, who named the new animal Bactrosaurus, or "club lizard", in reference to the large club-shaped neural spines projecting from some of the vertebrae.{{cite journal|last1=Gilmore|first1=C. W.|year=1933|title=On the dinosaurian fauna of the Iren Dabasu Formation|journal=Bulletin of the American Museum of Natural History|volume=67|issue=2|pages=23–78|hdl=2246/355}} The Iren Dabasu Formation has been dated to the Cenomanian stage, around 95.8 ± 6.2 million years ago.{{cite journal|last1=Guo|first1=Z. X.|last2=Shi|first2=Y. P.|last3=Yang|first3=Y. T.|last4=Jiang|first4=S. Q.|last5=Li|first5=L. B.|last6=Zhao|first6=Z. G.|title=Inversion of the Erlian Basin (NE China) in the early Late Cretaceous: Implications for the collision of the Okhotomorsk Block with East Asia|date=2018|journal=Journal of Asian Earth Sciences|volume=154|pages=49–66|doi=10.1016/j.jseaes.2017.12.007|bibcode=2018JAESc.154...49G|url=http://icpms.ustc.edu.cn/laicpms/publications/2018-GuoZX-JAES.pdf|access-date=2020-05-02|archive-date=2020-09-19|archive-url=https://web.archive.org/web/20200919173817/http://icpms.ustc.edu.cn/laicpms/publications/2018-GuoZX-JAES.pdf|url-status=dead}}
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)."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}}.
"Bakesaurus" is an informal name based on a maxilla from the Majiacun Formation of China assigned to Bactrosaurus in 2001.{{cite journal|last=Li|first=Z.|year=2001|title=Distribution, burying and classification of dinosaur fossils in Upper Cretaceous strata at Meipu Town, Yunxian County of Hubei Province|journal=Hubei Geology & Mineral Resources|volume=15|issue=4|pages=25–31}} The nomen nudum was created and pictured in a Chinese-language book by Zhou (2005){{cite book|last=Zhou|first=S.Q.D.|year=2005|title=The Dinosaur Egg Fossils in Nanyang, China|publisher=China University of Geosciences Press|pages=1–145|isbn=978-7-562-52033-7}} and first surfaced on the Internet during February 2006 when it was mentioned on the Dinosaur Mailing List by Jerry D. Harris.Harris, Jerry D., 2006. [http://dml.cmnh.org/2006Feb/msg00285.html "New Dinosaurs?"] {{Webarchive|url=https://web.archive.org/web/20160222180319/http://dml.cmnh.org/2006Feb/msg00285.html |date=2016-02-22 }}
Description
File:Bactrosaurus Museum of Ancient Life.jpg]]
A typical Bactrosaurus would have been {{convert|6|-|6.5|m|ft|abbr=on}} long and weighed {{convert|1.2|MT|ST}}.{{cite book|last1=Paul|first1=G. S.|title=The Princeton Field Guide to Dinosaurs|publisher=Princeton University Press|year=2016|isbn=9780691167664|edition=2nd|location=Princeton, New Jersey|pages=151−152}}{{cite journal|last=Prieto-Marquez|first=A.|year=2011|title=Cranial and appendicular ontogeny of Bactrosaurus johnsoni, a hadrosauroid dinosaur from the Late Cretaceous of northern China|journal=Palaeontology|volume=54|issue=4|pages=773−792|doi=10.1111/j.1475-4983.2011.01053.x|doi-access=|bibcode=2011Palgy..54..773P }} 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. It shows features intermediate between those of the two main hadrosaurid groups.{{cite book |editor=Palmer, D.|year=1999 |title= The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals|publisher= Marshall Editions|location=London|page= 146|isbn= 1-84028-152-9}} Its femur measured {{convert|80|cm|ft}} long.
Bactrosaurus was originally thought to be a lambeosaurine hadrosaurid, supposedly the oldest and most primitive known, and its crestless head was seen as an anomaly. A 1990 popular book suggested that it had an incompletely preserved crest, but recent studies place Bactrosaurus as a more basal hadrosauromorph.{{Cite journal|last1=Prieto-Márquez|first1=Albert|last2=Carrera Farias|first2=Miguel|date=2021|title=A new late-surviving early diverging Ibero-Armorican duck-billed dinosaur and the role of the Late Cretaceous European Archipelago in hadrosauroid biogeography|url=http://www.app.pan.pl/article/item/app008212020.html|journal=Acta Palaeontologica Polonica|volume=66|doi=10.4202/app.00821.2020|doi-access=free}} Basal members do not preserve hollow crests, so Bactrosaurus itself is likely to be crestless.
Paleobiology
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|last1=Rothschild|first1=B. M.|last2=Tanke|first2=D. H.|last3=Helbling II|first3=M.|last4=Martin|first4=L. D.|date=2003|title=Epidemiologic study of tumors in dinosaurs|journal=Naturwissenschaften|volume=90|issue=11|pages=495–500|doi=10.1007/s00114-003-0473-9|pmid=14610645|bibcode=2003NW.....90..495R|s2cid=13247222|url=http://doc.rero.ch/record/13884/files/PAL_E816.pdf }}
See also
References
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Category:Late Cretaceous dinosaurs
Category:Fossil taxa described in 1933