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.
Giraffatitan
Between 1914 and the 1990s, "Giraffatitan" was claimed to be the largest dinosaur known, (ignoring the possibly larger but lost "Amphicoelias") and thus the largest land animal in history. In the later part of the twentieth century several giant titanosaurians found appear to have surpassed "Giraffatitan" in terms of sheer mass. However, "Giraffatitan" and "Brachiosaurus" are still the largest brachiosaurid sauropods known from relatively complete material.