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a herbivorous titanosaurian sauropod dinosaur from the latest Cretaceous of North America.
Alamosaurus sanjuanensis
Pronunciation: AL-a-mo-SOR-us
Meaning: Ojo Alamo lizard
Author/s: Gilmore (1922)
Synonyms: None known
First Discovery: New Mexico, USA
Chart Position: 99

Alamosaurus sanjuanensis

When J.B Reeside discovered Alamosaurus in 1921, it was North America's first Late Cretaceous-aged sauropod dinosaur. Funnily enough, a hip bone and shoulder blade made Alamosaurus North America's best-represented titanosaurian sauropod too, mainly because the land of the free has yet to yield another. But, despite laying claim to a steady stream of fossils since then, the most attention has been drawn through a misinterpretation of its name (see etymology).

After a 2011 review of two enormous vertebrae (SMP VP-1850, collected in 2004 and SMP VP-2104, collected in 2006) from "Willow Wash", and a 30% complete femur (collected in 2003) from "De-na-zin" Wash, Alamosaurus gained some real notoriety by catapulting itself into the big league of dinosaurs. Pound-for-pound, it is genuinely comparable to the likes of Puertasaurus, Futalognkosaurus, and the mighty Argentinosaurus. In fact, the new specimens are so much bigger than the original fossils it seems likely that all studies prior to 2011 had been based on the study of unreliable juveniles. But at least we can now add Alamosaurus to the ever increasing ranks of confirmed armoured titanosaurs.

On June 15th 1937, George B. Pearce discovered a partial Alamosaurus skeleton on the southwest toe of Utah's North Horn Mountain that was catalogued as USNM 15660, and in 2009 Michael Brett-Surman realised that a single armour plate, bearing an identical catalogue number, was hidden away in the Smithsonian. Based on style and hand, it seems likely that the same person created both hand-written labels, and probably at the same time, suggesting the armour and skeleton represent one individual.

Alamosaurus lived in North America in the dying days of the dinosaurs (but never ventured north of Central Utah) and shared its yard with Tyrannosaurus rex. So it's quite fitting that its remains were eventually discovered in Texas, where General Custer also made his last stand.

(Ojo Alamo Lizard from San Juan)Etymology
Contrary to popular assertions, the name Alamosaurus has nothing to do with the Alamo in San Antonio, Texas, or the battle that was fought there. It was named for the Ojo Alamo formation in New Mexico, which took its name from the Ojo Alamo trading post. The trading post itself was named after a species of cottonwood tree or "poplar" (known as "Alamo" in Spanish) that grew beside a nearby spring.
The species epithet, sanjuanensis, is a reference to San Juan, the county in which it was discovered. "Ensis" is a genus of edible saltwater clam (known as "razors" in England and "spoots" in Scotland), and also means "sword" in Latin, but when used as a Latin suffix for a place name it means "pertaining to", "originating in", or just "from". Genus name and epithet were coined by Smithsonian paleontologist Charles W. Gilmore in 1922.
The first fossils Alamosaurus were discovered at Barrel Spring Arroyo in the Naashoibito Member of the Ojo Alamo Formation (thought by some to be the Upper Kirtland Formation), San Juan Basin, New Mexico, by geologist John B. Reeside jr. of the US Geological Survey in June 1921. For many moon paleontologists were convinced that the Ojo Alamo was deposited just before the K-Pg boundary. But even with signs pointing to a much older age than previously thought (perhaps early-mid Maastrichtian) Alamosaurus is still the last living sauropod known from anywhere. The Holotype (USNM 10486) is a shoulder blade.
Era: Mesozoic
Epoch: Late Cretaceous
Stage: Maastrichtian
Age range: 67-66 mya
Est. max. length: 34 meters
Est. max. hip height: ?
Est. max. weight: 65 tons
Diet: Herbivore
• Gilmore C.W. (August 16, 1921) "Discovery of sauropod dinosaur remains in the Upper Cretaceous of New Mexico". Science, New Series, Volume Liv., July-December 1921, P.274.
• Gilmore C.W. (1922) "A new sauropod dinosaur from the Ojo Alamo Formation of New Mexico". Smithsonian Miscellaneous Collections 72: 1-9.
• Gilmore C.W. (1946) "Osteology of Alamosaurus, a sauropod dinosaur from the Upper Cretaceous" in Reptilian fauna of the North Horn Formation of central Utah, Geological Survey professional paper: Issue 210, Part 1, Page 29.
• Palmer D. (Jan. 1999) "The Marshall llustrated Encyclopedia of Dinosaurs and Prehistoric Animals".
• Wilson J.A. (2002) "Sauropod dinosaur phylogeny: critique and cladistic analysis".
• Upchurch P, Barrett P.M, and Dodson P. (2004) "Sauropoda" in Weishampel, Dodson and Osmólska (eds.) "The Dinosauria: Second Edition".
• Fowler D.W. and Sullivan R.M. (2011) "The first giant titanosaurian sauropod from the Upper Cretaceous of North America".
• Carrano M.T. and D'Emic M.D. (2015) "Osteoderms of the Titanosaur Sauropod Dinosaur Alamosaurus sanjuanensis Gilmore, 1922".
• Ronald S. Tykoski , Anthony R. Fiorillo (2016) "An articulated cervical series of Alamosaurus sanjuanensis Gilmore, 1922 (Dinosauria, Sauropoda) from Texas: new perspective on the relationships of North America's last giant sauropod". Journal of Systematic Palaeontology. http://dx.doi.org/10.1080/14772019.2016.1183150.
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To cite this page:
Atkinson, L. "ALAMOSAURUS :: from DinoChecker's dinosaur archive".
›. Web access: 16th Dec 2017.