Anchisaurus

Phylogeny: Dinosauria > Saurischia > Sauropodomorpha > Plateosauria > Massopoda > Sauropodiformes > Anchisauridae

Overview: Anchisaurus is a good example of a basal sauropodomorph, though it’s by no means the most “primitive” of the sauropodomorphs known. More derived sauropodomorph lineages, such as the true sauropods, had already emerged by its time. They were far larger, quadrupedal animals. In the case of Anchisaurus, however, it was much smaller and retained the bipedal posture of its earlier ancestors. Being smaller had its advantages. Anchisaurus likely wasn’t especially agile when compared to some other dinosaurs of its size, but it certainly was in comparison to its larger kin. Its arms being freed up also allowed for their use in defense and foraging. Basal sauropodomorphs of its ilk tended to have large hand claws, useful for manipulating branches, digging up roots and for swatting at an attacker. Food sources for this animal included horsetails, ferns, cycads and conifers. Like other basal sauropodomorphs, Anchisaurus had fairly simple teeth.

The holotype specimen of Anchisaurus, consisting of a partial skeleton, was accidentally unearthed in the mid-1850’s, in the state of Massachusetts. Later, a researcher by the name of Edward Hitchcock Jr. would study the bones. He would make a connection between these fossils and a set of fossilized tracks his own father had described in the area decades before. Hitchcock would at first describe it under the name Megadactylus. Another paleontologist, Othniel C. Marsh, pointed out that said name was already in use for another taxon, so its current generic name was officially chosen by him in 1885. Its name, meaning “near lizard”, refers to how Marsh saw it as a transitional form between later and earlier dinosaurs. Anchisaurus is today classified as a basal sauropodomorph in the clade Sauropodiformes. This made it more closely related to true sauropods than it was to dinosaurs like Plateosaurus, despite it retaining so many basal traits.