PLEUROCOELUS

In 1858, sauropod remains were discovered in the Arundel Formation near Bladensburg, Maryland, by Philip Tyson and named Astrodon—star tooth—by Christopher Johnston, a dentist, no less, but without the requisite description for officialdom. Six years later, Joseph Leidy satisfied "the code", making Astrodon a valid dinosaur, and attributing the genus to Johnston anyway. Twenty-three years after that, more sauropod fossils were found in the same formation, but this time near Muirkirk, by John Bell Hatcher, a Yale collector earning a whopping $50 per month. True to form, there was no way that O.C. Marsh was ever going to assign the second batch of remains to a previously named dinosaur, especially one that someone else had named. Nor did he allow his "assistants" to steal his thunder by publishing their own finds. So, he used them to raise a new genus with two species—Pleurocoelus nanus and Pleurocoelus altus—in 1888.

It was Hatcher himself who first questioned whether more than one sauropod lurked in the Arundel, voicing doubts in 1903, more than a decade after leaving Yale. Charles Gilmore echoed the skepticism in 1921, and Carpenter and Tidwell joined the chorus in 2005. Yet despite being named on the strength of a pair of teeth—one of which was sawed into slices—Astrodon remains diagnostic and valid. And because it was described first, its name holds priority over all Arundel sauropod material.

This posed a political problem. Texas and Maryland had adopted Pleurocoelus and Astrodon as their official state dinosaurs, respectively. But our suggestion of a good ol' bout of fisticuffs to settle the issue fell on deaf ears, and Texas finally admitted defeat. On the 19th June 2009, by a landslide margin of 7 "ayes" to 0 "nays", the designation of the Official Dinosaur of the Lone Star state was changed to Paluxysaurus jonesi, a sauropod whose "tracks and bones litter the Jones Ranch" near Glen Rose, central Texas, and spent many-a-year wrongly assigned to Pleurocoelus. Alas, it was sunk as a synonym of Sauroposeidon in 2012.

You may think that's the end of the story as far as Pleurocoelus goes. However, there's still a Pleurocoelus valdensis (Lydekker, 1890) from the Wessex Formation of England, hanging on by the skin of its teeth—quite literally, as it too is known only from teeth.