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.
|Mounted skeleton of Coelophysis bauri, Cleveland Museum of Natural History|
Despite their very early occurrence in the fossil record, coelophysoids have a number of derived features that separate them from primitive (basal) theropods. Among the most prominent of these derived features (apomorphies) is the way the upper jaw bones are connected (the premaxilla-maxilla articulation), which is flexible with a deep gap between the teeth in the two bones. A major source of disagreement among theropod experts is whether or not coelophysoids shared a more recent common ancestor with Ceratosauria (sensu stricto) than the ceratosaurs did with other theropods. Most recent analyses indicate the latter, that Coelophysoidea does not form a natural group with the ceratosaurians. Similarly, while Dilophosaurus and similar theropods have traditionally been classified as coelophysoids, several studies published in the late 2000s suggested that they may actually be more closely related to the tetanurans.
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.Ceratosauria
Ceratosaurs are members of a group of theropod dinosaurs defined as all theropods sharing a more recent common ancestry with Ceratosaurus than with birds. Ceratosaurs are believed to have diverged from the rest of Theropoda by the early Jurassic, however, the oldest confirmed discovered specimens date to the Late Jurassic. According to the majority of the latest research, Ceratosauria includes the Late Jurassic to Late Cretaceous theropods Ceratosaurus, Elaphrosaurus, and Abelisaurus, found primarily (though not exclusively) 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.Ceratosauria derives its names from the type species, Ceratosaurus nasicornis, described by O.C. Marsh in 1884. A moderately large predator from the Late Jurassic, Ceratosaurus nasicornis, was the first ceratosaur to be discovered. Ceratosaurs are generally moderately large in size, with some exceptions like the larger Carnotaurus and the significantly smaller noasaurs. The major defining characteristics of Ceratosauria include a robust skull with increased ornamentation or height and a shortening of the arms. Both of these characteristics are generally accentuated in later members of the group, such as the abelisaurs, whereas more basal species such as C. nasicornis appear more similar to other basal theropods. The highly fragmented nature of the ceratosaur fossil record, means that the characteristics, relationships, and early history of Ceratosauria remain mysterious and highly debated.Coelophysidae
Coelophysidae is a family of primitive carnivorous theropod dinosaurs. Most species were relatively small in size. The family flourished in the Late Triassic and Early Jurassic periods, and has been found on numerous continents. Many members of Coelophysidae are characterized by long, slender skulls and light skeletons built for speed. One member, Coelophysis, displays the earliest known furcula in a dinosaur.Under cladistic analysis, Coelophysidae was first defined by Paul Sereno in 1998 as the most recent common ancestor of Coelophysis bauri and Procompsognathus triassicus, and all of that common ancestor's descendants. However, Tykoski (2005) has advocated for the definition to change to include the additional taxa of "Syntarsus" kayentakatae and Segisaurus halli. Coelophysidae is part of the superfamily Coelophysoidea, which in turn is a subset of the larger Neotheropoda clade. As part of Coelophysoidea, Coelophysidae is often placed as sister to the Dilophosauridae family, however, the monophyly of this clade has often been disputed. The older term "Podokesauridae", named 14 years prior to Coelophysidae (which would normally grant it priority), is now usually ignored, since its type specimen was destroyed in a fire and can no longer be compared to new finds.Coelophysis rhodesiensis
Coelophysis rhodesiensis is an extinct species of coelophysid theropod dinosaur that lived approximately 188 million years ago during the early part of the Jurassic Period in what is now Africa. The species was a small to medium-sized, lightly built, ground-dwelling, bipedal carnivore, that could grow up to 3 m (9.8 ft) long. It was formerly called Syntarsus, but that name was already taken by a beetle, and was subsequently given the name Megapnosaurus by Ivie, Ślipiński & Węgrzynowicz, in 2001, though many subsequent studies have classified it in the genus Coelophysis.Dilophosauridae
Dilophosauridae is a family of medium to large sized theropod dinosaurs. The name Dilophosauridae is derived from Greek, with “di” meaning “two,” “lophos” meaning “crest,” “sauros” meaning “lizard,” and “idae” meaning “family”. While the name suggests that all dilophosaurids have two crests, this is not applicable to all dilophosaurids. The Dilophosauridae is anchored by the genus Dilophosaurus, and therefore the name comes from the distinctive two crests of the genus.Dolichosuchus
Dolichosuchus (meaning "long crocodile") is the name given to a genus of dinosaur from the Triassic. It was originally classified in the disused family Hallopodidae, but has since been reclassified as a coelophysoid. A single fossil (consisting of a single lower leg bone, or tibia) was found in Germany. Since only one bone was discovered, the genus is considered a nomen dubium. Some scientists have noted that the tibia closely resembles those of Liliensternus and Dilophosaurus.The type species is D. cristatus, described by Huene in 1932. The bone was recovered from the Lower or Middle Stubensandstein formation.Dracoraptor
Dracoraptor is a genus of carnivorous neotheropod dinosaur from the Hettangian age of the Early Jurassic period of Wales.Eodromaeus
Eodromaeus (meaning "dawn runner") was a genus of basal theropod dinosaur known from the Late Triassic (Carnian) Valle de la Luna Member of the Ischigualasto Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina. It has been cited by Sereno as resembling a supposed common ancestor to all dinosaurs, the "Eve" of the dinosaurs.Gojirasaurus
Gojirasaurus (meaning "Godzilla lizard") is a dubious genus of coelophysoid theropod dinosaur named after the giant monster movie character Gojira (the Japanese name for the monster Godzilla).Gravisauria
Gravisauria is a clade of sauropod dinosaurs consisting of some genera, Vulcanodontidae and Eusauropoda.Lepidus praecisio
Lepidus is a genus of extinct coelophysoidean theropod from the Upper Triassic of the United States. It lived in the Otis Chalk localities of the Dockum Group in Texas, around 223 million years ago.Lophostropheus
Lophostropheus (pron.:" LOAF-oh-STRO-fee-us") is an extinct genus of coelophysoid theropod dinosaur that lived approximately 200 million years ago during the boundary between the Late Triassic Period and the Early Jurassic Period, in what is now Normandy, France. Lophostropheus is one of the few dinosaurs that may have survived the Triassic–Jurassic extinction event.
Lophostropheus was a small to medium-sized, moderately-built, ground-dwelling, bipedal carnivore, that could grow up to 3 m (9.8 ft) long. Over the years it had been incorrectly classified as Halticosaurus and Liliensternus, but was later recognized as a new genus and was reassigned to Lophostropheus in 2007.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.Notatesseraeraptor
Notatesseraeraptor ("feature mosaic tile thief"; from the Latin "nota", feature; "tesserae", tiles used to make a mosaic, in reference to the mixture of features normally found on dilophosaurids and coelophysoids; and "raptor", thief) is a genus of carnivorous theropod dinosaur that lived during the Late Triassic of what is now Switzerland. It was an early member of Neotheropoda with affinities to Dilophosaurus and Averostra. The new genus and species Notatesseraeraptor frickensis was named by Marion Zahner and colleagues in 2019.Since 1961, at the clay pit of Gruhalde, exploited by Tonwerke Keller, numerous fossils of Plateosaurus have been found. At a somewhat higher layer, in the spring of 2006, amateur paleontologist Michael Fisher discovered the postcranial skeleton of a small theropod. In 2009, the skull was secured. The fossils were unearthed and prepared by Ben Pabst and team. Initially the skeleton was provisionally referred to Coelophysidae. In 2008, parts of the postcranial skeleton were described in a master's thesis by Jasmina Christine Hugi. Lui Unterassner described the shoulder girdle and stomach content in his thesis of 2009, while Marion Zahner dedicated a thesis to the skull in 2014.In 2019, the type species Notatesseraeraptor frickensis gen. et sp. nov. was named and described by Marion Zahner and Winand Brinkmann. The generic name combines the Latin nota, "trait", tesserae, "mosaic tiles", and raptor, "predator". It refers to it being a carnivorous species showing a mix of traits of the Dilophosauridae and Coelophysoidea. The specific name refers to a provenance from the municipality of Frick in the Aargau. It represents the first Mesozoic theropod named from Switzerland.Podokesaurus
Podokesaurus ("swift-footed lizard") was a small carnivorous dinosaur that lived during the Pliensbachian–Toarcian stages of the Early Jurassic Period, and as such is one of the earliest known dinosaurs to inhabit the eastern United States.Powellvenator
Powellvenator is an extinct genus of coelophysoid theropod dinosaur that lived during the latter part of the Triassic Period in what is now northwestern Argentina. Fossils of the dinosaur were found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin. The type species, Powellvenator podocitus, was named by Martin Ezcurra in 2017.Sarcosaurus
Sarcosaurus (meaning "flesh lizard") is a genus of theropod dinosaur, roughly 3.5 metres (11 ft) long. It lived during the Sinemurian stage of the Early Jurassic, about 194 million years ago. Sarcosaurus is one of the earliest known Jurassic theropods, and one of only a handful of theropod genera from this time period.Theropoda
Theropoda ( or , from Greek θηρίον "wild beast" and πούς, ποδός "foot") or theropods () are a dinosaur suborder that is characterized by hollow bones and three-toed limbs. They are generally classed as a group of saurischian dinosaurs, although a 2017 paper has instead placed them in the proposed clade Ornithoscelida as the closest relatives of the Ornithischia. Theropods were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores, omnivores, piscivores, and insectivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago (Ma) and included the sole large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by about 10,500 living species.