North Horn Formation

Utah's North Horn Formation: Alamosaurus Fauna Assemblage. 

The North Horn Formation in Utah captures a faunal assemblage from the very end of the Cretaceous. While Utah has a strong record of dinosaurs from the Jurassic all the way through to the Campanian Stage of the Cretaceous, the Maastrichtian stage is not as well represented. Known fauna (as depicted here) include Torosaurus, Alamosaurus, Tyrannosaurus (shown here as a juvenile), the large lizard Polyglyphanodon, and small mammals. The Edmontosaurs are speculative, and based on DeCourten. Might have been more accurate to have displayed Kritosaurus, which is also assumed but not known.