Skeletal elements of "Alamosaurus" are among the most common Late Cretaceous dinosaur fossils found in the United States Southwest and are now used to define the fauna of that time and place, known as the ""Alamosaurus" fauna". In the south of Late Cretaceous North America, the transition from the Edmontonian to the Lancian faunal stages is even more dramatic than it was in the north. Thomas M. Lehman describes it as "the abrupt reemergence of a fauna with a superficially 'Jurassic' aspect." These faunas are dominated by "Alamosaurus" and feature abundant "Quetzalcoatlus" in Texas. The "Alamosaurus"-"Quetzalcoatlus" association probably represent semi-arid inland plains.