The Javelina Formation is a Late Cretaceous rock unit in Texas, especially well known in West Texas and Big Bend National Park, that preserves some of the last dinosaur-era life before the end-Cretaceous mass extinction. Research has refined its age and shown that its dinosaur fossils come from the upper part of the formation, very near the Cretaceous-Paleogene boundary. Its fossils include Alamosaurus, as well as reported ceratopsians, theropods, Quetzalcoatlus from related Late Cretaceous sediments in Big Bend, and turtles, fish, and plants. Plant remains indicate a woodland habitat, helping paleontologists reconstruct late Maastrichtian ecosystems in Texas shortly before the global transition.