The Tangled History of Connecticut’s Anchisaurus

East Coast dinosaurs are relatively rare finds, often because the geological formations in which they rest have been built over. Dinosaurs surely remain to be found under parking lots, housing developments and city streets, and one of the now-lost dinosaur quarries is located in Manchester, Connecticut.

During the 19th century the remains of several sauropodomorph dinosaurs were found in the Nutmeg State. These were the long-necked, small-headed precursors of the later, gigantic sauropod dinosaurs. Most of these were finds were very fragmentary, but in the late 1880s three partial skeletons were found at Wolcott's Quarry in Manchester. (This site has since been filled in.) Because this locality was not far from Yale, the famous paleontologist O.C. Marsh got the duty of describing the specimens.

Paleontologist Adam Yates, in his recent reanalysis of these dinosaurs, recounted the taxonomic tangle Marsh created. Despite the fact that all three specimens came from the same Early Jurassic-age quarry, Marsh attributed each fragmentary skeleton to a different species. Marsh named the first specimen Anchisaurus major (1889), the second was named Anchisaurus colurus (1891), and the third was given the title Anchisaurus solus (1892), although these names were not stable. Marsh renamed the first specimen Ammosaurus in 1891, the second specimen was renamed Yaleosaurus by Friedrich von Huene in 1932, and von Huene also transferred the third specimen to another species of Ammosaurus. What a mess!

Debates over the right name for these dinosaurs continued for decades and even reached into the early 21st century. Paleontologists eventually agreed that all the specimens belonged to just one species, but should that species be Ammosaurus or Anchisaurus? Yates makes a convincing argument that Anchisaurus polyzelus is the dinosaur's proper name.

About two decades prior to the Wolcott Quarry finds, the partial skeleton of a sauropodomorph dinosaur was found in Springfield, Massachusetts. It was given the name Megadactylus polzelus, but was changed to Amphisaurus by Marsh in 1882 and finally Anchisaurus in 1885 since both of the previously-used names were occupied. Obviously Anchisaurus and the Wolcott Quarry skeletons were the same general type of dinosaur, but a lack of distinguishing characteristics in the overlapping portions of the skeletons prevented paleontologists from grouping them all under the same name.

After looking at the skeletons again, however, Yates found peculiar features of the hip blade and part of the fused vertebrae which make up the hip. These features unite all the New England specimens, and this means that the older name—Anchisaurus—gets preference over Marsh's "Ammosaurus" for the Wolcott skeletons. After nearly a century and a half of uncertainty, we can now say that Anchisaurus polyzelus is the proper name for these dinosaurs.

References:

YATES, A. (2010). A revision of the problematic sauropodomorph dinosaurs from Manchester, Connecticut and the status of Anchisaurus Marsh Palaeontology, 53 (4), 739-752 DOI: 10.1111/j.1475-4983.2010.00952.x

Riley Black | | READ MORE

Riley Black is the author of The Last Days of the Dinosaurs and many other books. She is a science correspondent for Smithsonian magazine covering fossils and natural history, and she writes about the prehistoric past for a variety of publications.