page_title: Dilophosaurus
section_title: Classification
hierarchical_section_title: Dilophosaurus / Classification
caption_attribution_description: English: Dracovenator on display at the Royal Ontario Museum.
context_page_description: Dilophosaurus is a genus of theropod dinosaurs that lived in what is now North America during the Early Jurassic, about 193 million years ago. Three skeletons were discovered in northern Arizona in 1940, and the two best preserved were collected in 1942. The most complete specimen became the holotype of a new species in the genus Megalosaurus, named M. wetherilli by Samuel P. Welles in 1954. Welles found a larger skeleton belonging to the same species in 1964. Realizing it bore crests on its skull, he assigned the species to the new genus Dilophosaurus in 1970, as Dilophosaurus wetherilli. The genus name means "two-crested lizard", and the species name honors John Wetherill, a Navajo councilor. Further specimens have since been found, including an infant. Footprints have also been attributed to the animal, including resting traces. Another species, Dilophosaurus sinensis from China, was named in 1993, but was later found to belong to the genus Sinosaurus.
  At about 7 m in length, with a weight of about 400 kg, Dilophosaurus was one of the earliest large predatory dinosaurs and the largest known land-animal in North America at the time.
context_section_description: Welles thought Dilophosaurus a megalosaur in 1954, but revised his opinion in 1970 after discovering that it had crests. By 1974, Welles and the American paleontologist Robert A. Long found Dilophosaurus to be a ceratosauroid. In 1984 Welles found that Dilophosaurus exhibited features of both Coelurosauria and Carnosauria, the two main groups into which theropods had hitherto been divided, based on body size, and he suggested this division was inaccurate. He found Dilophosaurus to be closest to those theropods that were usually placed in the family Halticosauridae, particularly Liliensternus.
  In 1988, American paleontologist Gregory S. Paul classified the halticosaurs as a subfamily of the family Coelophysidae, and suggested that Dilophosaurus could have been a direct descendant of Coelophysis. Paul also considered the possibility that spinosaurs were late-surviving dilophosaurs, based on similarity of the kinked snout, nostril position, and slender teeth of Baryonyx. In 1994, American paleontologist Thomas R. Holtz placed Dilophosaurus in the group Coelophysoidea, along with but separate from the Coelophysidae. He placed the Coelophysoidea in the group Ceratosauria. In 2000 the American paleontologist James H. Madsen and Welles divided Ceratosauria into the families Ceratosauridae and Dilophosauridae, with Dilophosaurus as the sole member of the latter family.
  Lamanna and colleagues pointed out in 1998 that since Dilophosaurus was discovered to have had crests on its skull, other similarly crested theropods have been discovered (including Sinosaurus), and that this feature is, therefore, not unique to the genus, and of limited use for determining interrelationships within their group.  Australian paleontologist Adam M. Yates described the new genus Dracovenator from South Africa in 2005, and found it closely related to Dilophosaurus and Zupaysaurus. His cladistic analysis suggested they did not belong in the Coelophysoidea, but rather in the Neotheropoda, a more derived (or "advanced") group. He proposed that if Dilophosaurus was more derived than the Coelophysoidea, the features it shared with this group may have been inherited from basal (or "primitive") theropods, indicating that theropods may have passed through a "coelophysoid stage" in their early evolution.
  In 2007, American paleontologist Nathan D. Smith and colleagues found the crested theropod Cryolophosaurus to be the sister species of Dilophosaurus, and grouped them with Dracovenator and Sinosaurus. This clade was more derived than the Coelophysoidea, but more basal than the Ceratosauria, thereby placing basal theropods in a ladder-like arrangement. In 2012, Carrano and colleagues found that the group of crested theropods proposed by Smith and colleagues was based on features that relate to the presence of such crests, but that the features of the rest of the skeleton were less consistent. They instead found that Dilophosaurus was a coelophysoid, with Cryolophosaurus and Sinosaurus being more derived, as basal members of the group Tetanurae.
  Belgian paleontologist Christophe Hendrickx and colleagues defined the Dilophosauridae to include Dilophosaurus and Dracovenator in 2015, and noted that while  general uncertainty exists about the placement of this group, it appears to be slightly more derived than the Coelophysoidea, and the sister group to the Averostra. The Dilophosauridae share features with the Coelophysoidea such as the subnarial gap and the front teeth of the maxilla pointing forwards, while features shared with Averostra include a fenestra at the front of the maxilla and a reduced number of teeth in the maxilla. They suggested that the cranial crests of Cryolophosaurus and Sinosaurus had either evolved convergently, or were a feature inherited from a common ancestor. The following cladogram is based on that published by Hendrickx and colleagues, itself based on earlier studies:
  In 2019, Swiss paleontologists Marion Zahner and Winand Brinkmann found the members of the Dilophosauridae to be successive basal sister taxa of the Averostra rather than 
caption: Skull bones of Dracovenator, which may be the closest relative of Dilophosaurus (onto whose skull the bones are plotted), ROM
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