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.
History of paleontology in the United States
By the beginning of the 19th, their fossil footprints definitely had. Later in the century as more dinosaur fossils were uncovered eminent paleontologists Edward Drinker Cope and Othniel Charles Marsh were embroiled in a bitter rivalry to collect the most fossils and name the most new prehistoric species. Early in the 20th century major finds continued, like the Ice Age mammals of the La Brea Tar Pits, the Oligocene bonebeds of South Dakota, and the Triassic bonebeds of New Mexico. 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, cemented their sophisticated physiology and relationship with birds. Other notable finds include "Maiasaura", which provided early evidence for parental care in dinosaurs and ""Seismosaurus"" the largest known dinosaur.