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
The next year, 1979, two hikers found a series of gigantic articulated vertebrae fossils near San Ysidro. They reported the remains to David Gilette of the New Mexico Museum of Natural History. Gillette led an expedition into the region and used cutting edge technology to locate the remains while they were still entombed in sandstone. The team excavated a massive quarry and gradually recovered a significant portion of the rear half of a diplodocid sauropod dinosaur. In 1991 this dinosaur was formally described as the new genus "Seismosaurus" and estimated to be the longest dinosaur known to science at long.