Allosaurus is an extinct genus of large carnosaurian theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic period. The name "Allosaurus" means "different lizard", alluding to its unique concave vertebrae. It is derived from the Greek words ἄλλος and σαῦρος. The first fossil remains that could definitively be ascribed to this genus were described in 1877 by famed paleontologist Othniel Charles Marsh. As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles.
Ceratosaurus was a carnivorous theropod dinosaur that lived in the Late Jurassic period. The genus was first described in 1884 by American paleontologist Othniel Charles Marsh based on a nearly complete skeleton discovered in Garden Park, Colorado, in rocks belonging to the Morrison Formation. The type species is Ceratosaurus nasicornis.
Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with Ceratosaurus than with birds. The oldest known ceratosaur, Saltriovenator, dates to the earliest part of the Jurassic, around 199 million years ago. Ceratosauria includes three major clades: Ceratosauridae, Noasauridae, and Abelisauridae, found primarily in the Southern Hemisphere. Originally, Ceratosauria included the above dinosaurs plus the Late Triassic to Early Jurassic Coelophysoidea and Dilophosauridae, implying a much earlier divergence of ceratosaurs from other theropods. However, most recent studies have shown that coelophysoids and dilophosaurids do not form a natural group with other ceratosaurs, and are excluded from this group.
Tetanurae is a clade that includes most theropod dinosaurs, including megalosauroids, allosauroids, tyrannosauroids, ornithomimosaurs, compsognathids and maniraptorans. Tetanurans are defined as all theropods more closely related to modern birds than to Ceratosaurus and contain the majority of predatory dinosaur diversity. Tetanurae likely diverged from its sister group, Ceratosauria, during the late Triassic. Tetanurae first appeared in the fossil record by the Early Jurassic about 190 mya and by the Middle Jurassic had become globally distributed.
Torvosaurus is a genus of large megalosaurine theropod dinosaur that lived approximately 165 to 148 million years ago during the Callovian to Tithonian ages of the late Middle and Late Jurassic period in what is now Colorado, Portugal, Germany, and possibly England, Spain, Tanzania, and Uruguay. It contains two currently recognized species, Torvosaurus tanneri and Torvosaurus gurneyi, plus a third unnamed species from Germany.
Carcharodontosauridae is a group of carnivorous theropod dinosaurs. In 1931, Ernst Stromer named Carcharodontosauridae as a family, which, in modern paleontology, indicates a clade within Carnosauria. Carcharodontosaurids include some of the largest land predators ever known: Giganotosaurus, Mapusaurus, Carcharodontosaurus, and Tyrannotitan all rivaled Tyrannosaurus in size. Estimates give a maximum weight of 8–10 metric tons for the largest carcharodontosaurids, while the smallest carcharodontosaurids were estimated to have weighed at least 500 kilograms (1,100 lb).
Rugops is a monospecific genus of basal abelisaurid theropod dinosaur from Niger that lived during the Late Cretaceous period in what is now the Echkar Formation. The type and only species, Rugops primus, is known only from a partial skull. It was named and described in 2004 by Paul Sereno, Jeffery Wilson and Jack Conrad. Rugops has an estimated length of 4.4–5.3 metres and weight of 410 kilograms. The top of its skull bears several pits which correlates with overlaying scale and the front of the snout would have had an armour-like dermis.
Abelisauridae is a family of ceratosaurian theropod dinosaurs. Abelisaurids thrived during the Cretaceous period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are found on the modern continents of Africa and South America, as well as on the Indian subcontinent and the island of Madagascar. Isolated teeth were found in the Late Jurassic of Portugal, and the Late Cretaceous genera Tarascosaurus and Arcovenator have been described in France. Abelisaurids first appear in the fossil record of the early middle Jurassic period, and at least three genera survived until the end of the Mesozoic era 66 million years ago.
Allosauridae is a family of medium to large bipedal, carnivorous allosauroid theropod dinosaurs from the Late Jurassic. Allosauridae is a fairly old taxonomic group, having been first named by the American paleontologist Othniel Charles Marsh in 1878. Allosaurids are characterized by an astragalus with a restriction of the ascending process to the lateral part of the bone, a larger medial than lateral condyle, and a horizontal groove across the face of the condyles.
Deltadromeus is a genus of theropod dinosaur from Northern Africa. It had long, unusually slender hind limbs for its size, suggesting that it was a swift runner. The skull is not known. One fossil specimen of a single species has been described, found in the Kem Kem Beds, which date to the mid-Cretaceous Period, about 95 million years ago. It may be a junior synonym of the contemporary Bahariasaurus. The classification of Deltadromeus has been in flux since its original description. In 2016, a South American theropod known as Gualicho shinyae was found to possess many similarities with Deltadromeus. Depending on the phylogenetic position of Gualicho, Deltadromeus may have been a neovenatorid carnosaur, a tyrannosauroid, or a basal coelurosaur if its close relation to Gualicho is legitimate. Other studies have considered it a ceratosaurian, more specifically a member of the family Noasauridae.
Megalosauridae is a monophyletic family of carnivorous theropod dinosaurs within the group Megalosauroidea. Appearing in the Middle Jurassic, megalosaurids were among the first major radiation of large theropod dinosaurs. They were a relatively primitive group of basal tetanurans containing two main subfamilies, Megalosaurinae and Afrovenatorinae, along with the basal genus Eustreptospondylus, an unresolved taxon which differs from both subfamilies.
Abelisauroidea is a diverse superfamily of ceratosaurian dinosaurs, typically regarded as a Cretaceous group, though the earliest abelisaurid remains are known from the Middle Jurassic of Argentina and possibly Madagascar. Possible Abelisauridae remains were also discovered in Late Jurassic Tendaguru Beds in Tanzania.
Elaphrosaurus is a genus of ceratosaurian theropod dinosaur that lived approximately 154 to 150 million years ago during the Late Jurassic Period in what is now Tanzania in Africa. Elaphrosaurus was a medium-sized but lightly built member of the group that could grow up to 6.2 m (20 ft) long. Morphologically, this dinosaur is significant in two ways. Firstly, it has a relatively long body but is very shallow-chested for a theropod of its size. Secondly, it has very short hindlimbs in comparison with its body. Phylogenetic analyses indicate that this genus is likely a ceratosaur. Earlier suggestions that it is a late surviving coelophysoid have been examined but generally dismissed. Elaphrosaurus is currently believed to be a very close relative of Limusaurus, an unusual beaked ceratosaurian which may have been either herbivorous or omnivorous.
Saurophaganax, also known as Allosaurus maximus or Saurophagus maximus, is a genus of large allosaurid dinosaur from the Morrison Formation of Late Jurassic Oklahoma, United States. Some paleontologists consider it to be a junior synonym and species of Allosaurus. Saurophaganax represents a very large Morrison allosaurid characterized by horizontal laminae at the bases of the dorsal neural spines above the transverse processes, and "meat-chopper" chevrons. It was the largest terrestrial carnivore of North America during the Late Jurassic, reaching 10.5 metres (34 ft) in length and 2.7–3.8 metric tons in body mass.
Genyodectes is a genus of ceratosaurian theropod dinosaur from the Lower Cretaceous (Aptian) of South America. The holotype material was collected from the Cerro Barcino Formation, Cañadón Grande, Departamento Paso de Indios in the Chubut Province of Argentina and consists of an incomplete snout, including the premaxillae, portions of both maxillas, the right and left dentary, many teeth, a fragment of the left splenial, and parts of the supradentaries. These elements are generally poorly preserved and some are in articulation. The premaxilla of Genyodectes possesses relatively large and protruding teeth, similar to those of Ceratosaurus. The specific name, serus, means "late". In 2016 it was estimated to be 6.25 meters in length and 790 kg in weight.
Limusaurus is a genus of theropod dinosaur that lived in what is now China during the Late Jurassic, around 161 to 157 million years ago. The type and only species Limusaurus inextricabilis was described in 2009 from specimens found in the Upper Shishugou Formation in the Junggar Basin of China. The genus name consists of the Latin words for "mud" and "lizard", and the species name means "impossible to extricate", both referring to these specimens possibly dying after being mired. Limusaurus was a small, slender animal, about 1.7 m in length and 15 kg (33 lb) in weight, which had a long neck and legs but very small forelimbs. It underwent a drastic morphological transformation as it aged: while juveniles were toothed, these teeth were completely lost and replaced by a beak with age. Several of these features were convergently similar to the later ornithomimid theropods as well as the earlier non-dinosaurian shuvosaurids.
Ostafrikasaurus is a genus of theropod dinosaur from the Late Jurassic period of what is now Lindi Region, Tanzania. It is known only from fossil teeth discovered sometime between 1909 and 1912, during an expedition to the Tendaguru Formation by the Natural History Museum of Berlin. Eight teeth were originally attributed to the dubious dinosaur genus Labrosaurus, and later to Ceratosaurus, both known from the North American Morrison Formation. Subsequent studies attributed two of these teeth to a spinosaurid dinosaur, and in 2012, Ostafrikasaurus crassiserratus was named by French palaeontologist Eric Buffetaut, with one tooth as the holotype, and the other referred to the same species. The generic name comes from the German word for German East Africa, the former name of the colony in which the fossils were found, while the specific name comes from the Latin words for "thick" and "serrated", in reference to the form of the animal's teeth.
Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.
This timeline of ceratosaur research is a chronological listing of events in the history of paleontology focused on the ceratosaurs, a group of relatively primitive, often horned, predatory theropod dinosaurs that became the apex predators of the southern hemisphere during the Late Cretaceous. The nature and taxonomic composition of the Ceratosauria has been controversial since the group was first distinguished in the late 19th century. In 1884 Othniel Charles Marsh described the new genus and species Ceratosaurus nasicornis from the Late Jurassic Morrison Formation of the western United States. He felt that it belonged in a new family that he called the Ceratosauridae. He created the new taxon Ceratosauria to include both the Ceratosauridae and the ostrich-like ornithomimids. The idea of the Ceratosauria was soon contested, however. Later that same decade both Lydekker and Marsh's hated rival Edward Drinker Cope argued that the taxon was invalid.
