The near lizard, Anchisaurus (1865)
Phylum : Chordata
Class : Reptilia
Order : Saurischia
Suborder : Sauropodomorpha
Genus : Anchisaurus
Species : A. polyzelus
Sauropodomorph remains were first discovered in North America in 1818, when some large bones were discovered by Mr. Solomon Ellsworth while excavating a well in East Windsor, Connecticut. At the time of their discovery the bones were assumed to be those of a human, but the presence of tail bones quickly falsified that idea and they are now recognized as those of an indeterminate sauropodomorph, possibly more closely related to the plateosaurian prosauropods. In 1857 the type specimen of Anchisaurus polyzelus, which is housed at the Amherst College Museum of Natural History, was found by William Smith in Springfield, Massachusetts during blasting for a well at the Springfield Armory. Unfortunately, both the East Windsor and Springfield specimens were severely damaged due to the blasting at the construction sites where they were found, and many of the bones were either accidentally thrown away by the workmen or kept by interested onlookers. Thus these dinosaurs were only known from incomplete remains. Luckily, in 1884 nearly complete specimens were found in Manchester, Connecticut and served as the templates from which O.C. Marsh restored the skeleton. The Manchester specimens are now considered conspecific with Anchisaurus polyzelus. The East Windsor and Manchester specimens are housed at the Peabody Museum of Natural History at Yale University.
Digesting plant matter is a much more intensive biochemical process than digesting meat. This herbivore swallowed gastroliths (gizzard stones) to help break down the food in its stomach. Herbivorous dinosaurs needed a huge gut. Since this had to be positioned in front of the pelvis, balancing on two legs became increasingly difficult, as dinosaurs became larger and they gradually evolved into the quadrupedal position that characterizes the later sauropods such as Diplodocus. Prosauropods represented a middle phase between the earliest bipedal herbivores and the later giant sauropods. Although it was not itself a prosauropod, Anchisaurus was mostly typical of this group, which flourished briefly during the late Triassic and early Jurassic. Anchisaurus teeth, used to rip food, were shaped like spoons. It had fewer and more widely spaced teeth than true prosauropods, and as Peter Galton and Michael Cluver observed, narrower feet.Anchisaurus would have spent most of its time on four legs but could have reared up on its hind legs to reach higher plants.
On the other hand, some paleontologists believe Anchisaurus may also have eaten meat, as it was in the transition between these two ultimately distinct groups. The teeth were blunt but with file-like edges, suggesting mostly plant matter was eaten and the jaw hinge was arranged in a way not entirely suited for tearing meat. Nevertheless, there is still some debate. The thumb had a large claw and the large eyes were not entirely on the side.
As a quadrupedal/bipedal crossover, Anchisaurus had to have multi-purpose front legs. As ‘hands’, they could be turned inwards and be used for grasping. It had a simple reversible first ‘finger’, similar to a ‘thumb’. As feet, the five toes could be placed flat against the floor and were strong at the ankle. This unspecialized design is typical of the early dinosaurs.