Wang and colleagues furthermore found that Ceratosaurus and Genyodectes form a clade with the Argentinian genus Eoabelisaurus. Delcourt used the name Ceratosauridae to refer to this same clade, and suggested to define the Ceratosauridae as containing all taxa that are more closely related to Ceratosaurus than to the abelisaurid Carnotaurus. The following cladogram showing the relationships of Ceratosaurus is based on the phylogenetic analysis conducted by Diego Pol and Oliver Rauhut in 2012: A skull from the Middle Jurassic of England apparently displays a nasal horn similar to that of Ceratosaurus. In 1926, Friedrich von Huene described this skull as Proceratosaurus (meaning "before Ceratosaurus"), assuming that it was an antecedent of the Late Jurassic Ceratosaurus. Today, Proceratosaurus is considered a basal member of the Tyrannosauroidea, a much more derived clade of theropod dinosaurs; the nasal horn therefore would have had evolved independently in both genera. Oliver Rauhut and colleagues, in 2010, grouped Proceratosaurus within its own family, the Proceratosauridae. These authors also noted that the nasal horn is incompletely preserved, opening the possibility that it represented the foremost portion of a more extensive head crest, as seen in some other proceratosaurids such as Guanlong. Paleobiology Ecology and feeding Within the Morrison and Lourinhã Formation, Ceratosaurus fossils are frequently found in association with those of other large theropods, including the megalosaurid Torvosaurus and the allosaurid Allosaurus. The Garden Park locality in Colorado contained, besides Ceratosaurus, fossils attributed to Allosaurus. The Dry Mesa Quarry in Colorado, as well as the Cleveland-Lloyd Quarry and the Dinosaur National Monument in Utah, feature, respectively, the remains of at least three large theropods: Ceratosaurus, Allosaurus, and Torvosaurus. Likewise, Como Bluff and nearby localities in Wyoming contained remains of Ceratosaurus, Allosaurus, and at least one large megalosaurid. Ceratosaurus was a rare element of the theropod fauna; it is outnumbered by Allosaurus at an average rate of 7.5 to 1 in sites where they co-occur. Several studies attempted to explain how these sympatric species could have reduced direct competition. Donald Henderson, in 1998, argued that Ceratosaurus co-occurred with two separate potential species of Allosaurus, which he denoted as "morphs": a morph with a shortened snout, a high and wide skull, and short, backwards-projecting teeth, and a morph characterized by a longer snout, lower skull, and long, vertical teeth. Generally speaking, the greater the similarity between sympatric species regarding their morphology, physiology, and behavior, the more intense competition between