Astrodon

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Astrodon

Fossil

Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Order:	Saurischia
Suborder:	Sauropodomorpha
Infraorder:	Sauropoda
Family:	Titanosauriformes
Genus:	Astrodon
Species:	A. johnstoni

Binomial name

Astrodon johnstoni
Leidy, 1865

Astrodon was a genus of large herbivorous dinosaur, related to Brachiosaurus, that lived in what is now the eastern United States during the Early Cretaceous period. Palynomorphs have been used to date the Arundel to the Aptian, which is 121-112 million years ago. Adults are estimated to have been more than 30 feet (9.1 m) high and 50 (15.2 m) to 60 (18.3 m) feet long.

[edit] Discovery and species

Two teeth were found in the Arundel Formation near Bladensburg, Maryland and named Astrodon in 1859 by Christopher Johnston. However, Johnston did not attach a specific epithet, so Joseph Leidy is credited with naming Astrodon johnstoni (the type species) in 1865. If Johnston had attached a scientific epithet, it would have been the second dinosaur identified in the United States.

In 1888, O.C. Marsh named some bones from the Arundel found near Muirkirk, Maryland Pleurocoelus nanus and P. altus. However, in 1921 Charles W. Gilmore argued that the name Astrodon had priority, a position that Carpenter and Tidwell (2005) accepted in the first in-depth description of this dinosaur. Interestingly, the majority of the bones of Astrodon are of juveniles. Astrodon is sometimes considered a synonym of Pleurocoelus, but the jury is still out on which name is correct. Carpenter and Tidwell therefore consider the two species named by Marsh, nanus and altus, as different growth stages of Astrodon johnsoni.^[1]

In 1998, Astrodon johnstoni was named the state dinosaur of Maryland.

[edit] References

^ Carpenter, Kenneth and Tidwell, Virginia (2005). "Reassessment of the Early Cretaceous Sauropod Astrodon johnsoni Leidy 1865 (Titanosauriformes)", in Carpenter, Kenneth and Tidswell, Virginia (ed.): Thunder Lizards: The Sauropodomorph Dinosaurs. Indiana University Press, 38–77. ISBN 978-0-253-34542-4.