Ammosaurus This may (or may not) have been the same dinosaur as Anchisaurus.

Ampelosaurus One of the best-known of the armored titanosaurs.

Amphicoelias Could it have been the biggest dinosaur that ever lived?

Amurosaurus The most complete hadrosaur to be discovered in Russia.

Anabisetia The best-attested South American ornithopod.

Anatosaurus This dinosaur is now known as either Anatotitan or Edmontosaurus.

Anatotitan This hadrosaur's name means "giant duck."