Dinosaurs / Cretaceous / Alamosaurus
Alamosaurus
Cretaceous AL-ah-moh-SAWR-us, “Ojo Alamo lizard”
Alamosaurus was a colossal titanosaur and the final sauropod known to have walked North America prior to the mass extinction sixty-six million years ago. Named after New Mexico's Ojo Alamo Formation rather than the famous historical mission, fossils of this behemoth are also well documented in Texas and Utah. Fully grown individuals were immense, reaching up to thirty metres in length and tipping the scales at around forty to fifty tonnes, rivalling giant South American forms. Alamosaurus arrived in southern North America late in the Cretaceous, likely dispersing from South America across an island chain. With columnar legs, broad hips, and tough osteoderm-studded skin, it dominated its arid floodplain environment, easily out-bulking its contemporary predator Tyrannosaurus rex.
It was the only known sauropod living in North America at the very end of the Cretaceous period.
Where and when
Alamosaurus lived in the Late Cretaceous, from 70 to 66 million years ago (Maastrichtian age). Its remains come from United States, in the Ojo Alamo Formation.
The numbers
Length 30 m (estimates run from 28 to 32 m). Mass about 42 t. Hip height about 6.5 m. That is 17.6 human-lengths, or 2.68 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.