The composite term Gojirasaurus is derived from the name of the giant Japanese movie monster "Gojira" (Godzilla) and the Greek word "sauros" (σαυρος) meaning "lizard"; thus, "Godzilla lizard". In addition, a theropod dinosaur with the name Godzillasaurus exists in the Heisei era of Godzilla films, and in that continuity is explained to be the unmutated form of Godzilla. "Gojira" was selected as a reference to the great size of this theropod, which exceeded that of its Triassic counterparts. The specific name quayi, is a reference to Quay County, New Mexico, where the holotype specimen was discovered. Gojirasaurus was described and named by Kenneth Carpenter in 1997 and the type species is Gojirasaurus quayi.
Gojirasaurus is one of the largest meat-eating dinosaurs known from the Triassic Period, almost the size of its relative, the large coelophysoid Dilophosaurus. The size of its tibia was 469 mm, which was comparable to that of Liliensternus (409 mm) and Dilophosaurus (555 mm), suggesting that it was a large triassic dinosaur, estimated to be about 5.5 m (18 ft) long, which can be extrapolated to a weight of approximately 150–200 kg (330–440 lb). Carpenter (1997) pointed to features of the pelvis and ankle suggesting that this was an immature individual, and could therefore have grown to even a larger size in maturity. Specimen NMMNH P-4666, which consists of only a pubis, was referred to this genus by Hunt in 1994.
In 1994 Adrian Hunt, in his unpublished thesis, described and named this material "Revueltoraptor lucasi" which is now considered a nomen nudum. Carpenter officially described and named UCM 47221, Gojirasaurus quayi in 1997 and classified it as a coelophysoid. The original remains attributed to this dinosaur included a serrated tooth, a cervical rib, two anterior dorsal ribs, one posterior dorsal rib, a right scapula, two gastralia, four vertebrae, one anterior chevron, a right pubis, a left tibia, and one metatarsal. Tykoski and Rowe (2004) and later Carrano et al. (2005) agreed that Gojirasaurus is more derived than Dilophosaurus However, later study by Nesbitt et al. (2007) showed that the vertebrae actually belonged to the rauisuchian Shuvosaurus, and the pubis and tibia belonged to another coelophysoid, indistinguishable from the contemporary Coelophysis, making the status of Gojirasaurus as a valid genus dubious.
A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism or group.
According to Nesbitt et al. (2007), Gojirasaurus can be distinguished based on the fact that its tibia is more robust than that of its relative Coelophysis. Mortimer (2012) has proposed that the observed difference in the leg bone might be just size-related, and not a true apomorphy. Rauhut (2003) attempted to diagnose this genus based on the fact that the mid/posterior dorsal vertebrae had taller neural spines than those observed in other coelophysoids. However, the reassignment of the dorsal vertebrae on which the diagnosis was based would render it invalid.
The only known specimen of Gojirasaurus was discovered in the Cooper Canyon Formation of the Dockum Group near Revuelto Creek, Quay County, in New Mexico. This genus was discovered in 1981, in gray carbonaceous mudstone deposited during the Norian stage of the Late Triassic, which based on magnetostratigraphy, was approximately 228 to 208 million years ago. This specimen is housed in the collection of the University of Colorado Museum, in Boulder, Colorado. Gojirasaurus's assignment to the Coelophysoidea, would suggest that it was a bipedal, terrestrial, actively mobile carnivore. Contemporaries of Gojirasaurus included the pseudosuchian Shuvosaurus, and the phytosaur Rutiodon.
The Anchisauria were a clade of sauropodomorph dinosaurs that lived during the Late Triassic and Early Jurassic. The name Anchisauria was first used by Galton and Upchurch in the second edition of The Dinosauria. Galton and Upchurch assigned two families of dinosaurs to the Anchisauria: the Anchisauridae and the Melanorosauridae. The more common prosauropods Plateosaurus and Massospondylus were placed in the sister clade Plateosauria.
However, recent research indicates that Anchisaurus is closer to sauropods than traditional prosauropods; thus, Anchisauria would also include Sauropoda.The following cladogram simplified after an analysis presented by Blair McPhee and colleagues in 2014.Averostra
Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.Avetheropoda
Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.Cerapoda
Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.Coelophysoidea
Coelophysoidea were common dinosaurs of the Late Triassic and Early Jurassic periods. They were widespread geographically, probably living on all continents. Coelophysoids were all slender, carnivorous forms with a superficial similarity to the coelurosaurs, with which they were formerly classified, and some species had delicate cranial crests. Sizes range from about 1 to 6 m in length. It is unknown what kind of external covering coelophysoids had, and various artists have portrayed them as either scaly or feathered. Some species may have lived in packs, as inferred from sites where numerous individuals have been found together.
Examples of coelophysoids include Coelophysis, Procompsognathus and Liliensternus. Most dinosaurs formerly referred to as being in the dubious taxon "Podokesauridae" are now classified as coelophysoids.Dinosauriformes
Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.Haya griva
Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.Jeholosauridae
Jeholosaurids were herbivorous neornithischian dinosaurs from the Cretaceous Period (Aptian - Santonian, with a possible Campanian record) of Asia. The family was first proposed by Han et al. in 2012. The jeholosaurids were defined as those ornithischians more closely related to Jeholosaurus shangyuanensis than to Hypsilophodon foxii, Iguanodon bernissartensis, Protoceratops andrewsi, Pachycephalosaurus wyomingensis, or Thescelosaurus neglectus. The Jeholosauridae includes the type genus Jeholosaurus and Yueosaurus.Jingshanosaurus
Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.Melanorosauridae
The Melanorosauridae were a family of sauropodomorph dinosaurs which lived during the Late Triassic and Early Jurassic. The name Melanorosauridae was first coined by Friedrich von Huene in 1929. Huene assigned several families of dinosaurs to the infraorder "Prosauropoda": the Anchisauridae, the Plateosauridae, the Thecodontosauridae, and the Melanorosauridae. Since then, these families have undergone numerous revisions. Galton and Upchurch (2004) considered Camelotia, Lessemsaurus, and Melanorosaurus members of the family Melanorosauridae. A more recent study by Yates (2007) indicates that the melanorosaurids were instead early sauropods.Neotheropoda
Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra.Norian
The Norian is a division of the Triassic geological period. It has the rank of an age (geochronology) or stage (chronostratigraphy). The Norian lasted from ~227 to 208.5 million years ago. It was preceded by the Carnian and succeeded by the Rhaetian.Orionides
Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.Orodrominae
Orodrominae is a subfamily of parksosaurid dinosaurs from the Cretaceous of North America and Asia.Riojasauridae
Riojasauridae is a family of sauropod-like dinosaurs from the Upper Triassic. It is known primarily from the genera Riojasaurus and Eucnemesaurus. Sites containing Riojasauridae include the Lower Elliot Formation of Orange Free State, South Africa (where fossils of Eucnemesaurus have been found), and Ischigualasto, in La Rioja Province, Argentina ( where fossils of Riojasaurus have been recovered).Unaysauridae
Unaysauridae is a family of basal sauropodomorphs from the Late Triassic of India and Brazil.Xixiposaurus
Xixiposaurus is a genus of prosauropod dinosaur which existed in what is now Lower Lufeng Formation, China during the lower Jurassic period. It was first named by Sekiya Toru in 2010 and the type species is Xixiposaurus suni.Yueosaurus
Yueosaurus is an extinct genus of basal ornithopod dinosaur known from Zhejiang Province, China.