The Agrosaurus was first discovered in Australia. The information on this dinosaur is very inconclusive due to a major error in which the fossils for this, already named dinosaur, is thought to be actually from a Thecodontosaurus, or a creature from its family. Theocodotosaurus was a newer member of the sauropdomorph group, which did have a lot of common with the Agrosaurus.

There has not been a full fossil body found either. Its rumored that in 1844, a few members of the British ship HMS fly found and collected a claw, a tibia, and a few other low profile fossils. The fossils were purchased by the British Museum of natural history, but not studied until 1891.

In 1981 the fossil was being prepared by Harry Seeley identified the dinosaur.

In 1991 a man named Ralph Molnar mentioned the Agrosaurus and the Massospondylus were very simular. Not only that, but also the Anchisaurus as well.