Anchisaurus was a prosauropod dinosaur whose fossils have been found in America’s northeastern states of Massachusetts and Connecticut within rocks dated to the beginning of the Jurassic Period, about 200-190 million years ago. Anchisaurus is one of the more well-known prosauropod dinosaurs, along with Plateosaurus of central Europe and Massospondylus of southern Africa.

Anchisaurus‘ total length cannot be conclusively ascertained because we don’t have a complete tail – only the front half of the tail was found. Estimates of the animal’s total length vary from 6 to 13 feet long, but the most common estimates which I have seen place the animal measuring somewhere between 8 to 10 feet in length.

Most reconstructions portray this animal walking quadrupedally or else rearing up on its hind legs to eat the leaves from overhanging tree branches. However, the evidence suggests that Anchisaurus was actually bipedal.

Anchisaurus polyzelus. © Jason R. Abdale (October 26, 2022).

Remains of Anchisaurus have been confined only to New England, but its native range was probably much broader than this. Fossil footprints dated to the late Triassic/early Jurassic transition which have been attributed to the theropod dinosaurs Coelophysis and Dilophosaurus (animals whose skeletal remains are known from New Mexico and Arizona) have been found in Massachusetts, Connecticut, New York, and New Jersey. If it’s true that these footprints did indeed belong to these species, then it is evidence that these animals were able to travel from the American Southwest to New England. If so, then the reverse could also be true – dinosaurs which were native to the northeastern United States, such as Anchisaurus, would have been perfectly capable of traveling overland from Connecticut to Arizona. As such, Anchisaurus was likely preyed upon by Coelophysis and Dilophosaurus.

Categories: Paleontology, Uncategorized

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3 replies

  1. What is the formation that Anchisaurus comes from? I only knew about the Kayenta Formation in early Jurassic North America, so it’s exciting to learn about another one, and possibly others.

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