AMMOSAURUS

Ammosaurus major is one of the first non-sauropod sauropodomorphs known from North America and one of the few to survive into the Middle Jurassic, but it was initially assigned by O.C. Marsh to his Anchisaurus as Anchisaurus major when it's partial rear-end was discovered in the Connecticut sandstone quarry of Charles O. Wolcott in 1889. Unfortunately, the rest of it was in bits in South Manchester, stuck in a bridge that was built with blocks cut from the same quarry sometime earlier. Nevertheless, Marsh pin-pointed enough differences in what he had available to separate his new specimen from the name-bearing Anchisaurus polyzelus from Springfield Armoury in Massachusetts in 1891 and enough similarities in two more specimens from Walcott's quarry to raise Anchisaurus solus and Anchisaurus colurus the same year.

It's been all go since then, what with Anchisaurus solus (Marsh, 1891) being renamed Ammosaurus solus (Marsh 1892) and then sunk into Ammosaurus major (Galton, 1971), and Anchisaurus colurus (Marsh 1891) being renamed Yaleosaurus (Von Huene, 1932), identified as the female form of Anchisaurus polyzelus (Galton, 1971) and nominated as the Anchisaurus name-bearer in 2015 due to its infinitely better fossils (Galton, 2012). All that chopping and changing left one species each of Anchisaurus and Ammosaurus, with the latter being bolstered by fragments from Manchester Bridge that were gathered by John Ostrom after its demolition in 1969. However, most experts believe that there is only one sauropodomorph present in Connecticut/Massachusetts, and that sauropodomorph is Anchisaurus because it was named first.