English: Alamosaurus is a genus of titanosaurian sauropod dinosaurs from the late Cretaceous Period of what is now southern North America. It was a gigantic quadrupedal herbivore with a long neck and tail and relatively long limbs. Its body was at least partly covered in bony armor. Alamosaurus was the largest dinosaur yet discovered from North America, growing to a length of about 30 m and an approximate weight of 80 t. It is the only known sauropod to have inhabited North America after their nearly 30-million year absence from the North American fossil record, and probably represents an immigrant from South America.