STL Science Center

STL Science Center

25 January 2013

Starry Teeth

Big bad East Coast dinosaurs. We took a small trip to South America last week, but we are back in North America and back along the Eastern Seaboard of the United States this week; a perfect jumping off point for next week coincidentally. However, we have a specimen in front of us this week that warrants not jumping the gun. Two teeth, gathered from Maryland (it is astounding how little can be used to describe a species sometimes), were described by a man called Christopher Johnston in 1859. Johnston was reluctant to go more specific than naming a genus so it fell to Joseph Leidy in 1865 to attribute a species to the named genus and the dental remains of the animal. He named the species after Johnston and the generic name, which describes the star shaped teeth, was added to it to create an animal thenceforth known as Astrodon johnstoni. How do we know anything from those teeth? Years later O.C. Marsh was given some bone from the Arundel formation of Maryland, where the teeth had come from, and he named those bones Pleuorcoelus nanus and P. altus. Thanks to subsequent detective work in 1903 by John Bell Hatcher the teeth of Pleurocoelus were recognized as identical to those of Astrodon and, with further corroboration in 1921 by Charles Gilmore, Pleurocoelus was relegated to the history books as a younger, and therefore junior, synonym of Astrodon. I am thankful for this as Astrodon is a much more interesting name in my mind. Astrodon is a relative of Brachiosaurus and resides in the Titanosauridae clade; two distinctions that make it known that this was a big animal. How big? Approximately 9m (30ft) tall and 15 to 18m (50 to 60ft) long. I will get back to everyone on estimated weight, but meandering along the Eastern Seaboard in the Early Cretaceous, this was a large dinosaur, and, though this image does not show it to scale with anything, we can certainly get that sense:

©Dmitry Bogdanov

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