Alamosaurus
Alamosaurus (; meaning "Ojo Alamo lizard") is a genus of titanosaurian sauropod dinosaurs, containing a single known species, Alamosaurus sanjuanensis, from the late Cretaceous Period of what is now southern North America. Isolated vertebrae and limb bones indicate that it reached sizes comparable to "Argentinosaurus" and "Puertasaurus", which would make it the largest dinosaur known from North America. Its fossils have been recovered from a variety of rock formations spanning the Maastrichtian age of the late Cretaceous period. Specimens of a juvenile "Alamosaurus sanjuanensis" have been recovered from only a few meters below the Cretaceous-Paleogene boundary in Texas, making it among the last surviving non-avian dinosaur species.
Paleontology in the United States
Early in the 20th century major finds continued, such as the Ice Age mammals of the La Brea Tar Pits. Mid-to-late twentieth-century discoveries in the United States triggered the Dinosaur Renaissance as the discovery of the bird-like "Deinonychus" overturned misguided notions of dinosaurs as plodding lizard-like animals, highlighting their sophisticated physiology and apparent relationship with birds. Other notable finds in the United States include "Maiasaura", which provided early evidence for parental care in dinosaurs and ""Seismosaurus"", the largest known dinosaur.