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.

Neotheropods
Temporal range:
Late TriassicPresent, 220–0 Ma
Coelophysis mount NHM2
Cast of a Coelophysis bauri skeleton
House sparrow04
A house sparrow (Passer domesticus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Clade: Neotheropoda
Bakker, 1986
Subgroups
Synonyms
  • Avepoda Paul, 2002
  • Eutheropoda Novas, Haro & Canale, 2003

Classification

Neotheropoda was named by Robert T. Bakker in 1986 as a group including the relatively advanced theropod subgroups Ceratosauria and Tetanurae.[1] However, most later researchers have used it to denote a broader group. Neotheropoda was first defined as a clade by Paul Sereno in 1998 as Coelophysis plus modern birds, which includes almost all theropods except the most primitive species.[2]

The following family tree illustrates a synthesis of the relationships of the early theropod groups compiled by Hendrickx et al. in 2015.[3]

Theropoda

Herrerasauridae

Eoraptor

Eodromaeus

Tawa

Daemonosaurus

Neotheropoda

CoelophysoideaCoelophysis Jeff Martz (flipped)

Liliensternus

Zupaysaurus

DilophosauridaeDilophosaurus wetherilli (flipped)

Averostra

CeratosauriaCeratosaurus nasicornis DB

TetanuraeMeyers grosses Konversations-Lexikon - ein Nachschlagewerk des allgemeinen Wissens (1908) (Antwerpener Breiftaube).jpg

References

  1. ^ Bakker, R.T. 1986. The Dinosaur Heresies. William Morrow, New York. 481 pp.
  2. ^ Sereno, 1998. A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 210, 41-83.
  3. ^ Hendrickx, C., Hartman, S.A., & Mateus, O. (2015). An Overview of Non- Avian Theropod Discoveries and Classification. PalArch’s Journal of Vertebrate Palaeontology, 12(1): 1-73.
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.

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.

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.

Daemonosaurus

Daemonosaurus (pron.:"DAY-mow-no-SORE-us") is an extinct genus of theropod dinosaur from the Late Triassic of New Mexico. Fossils have been found from deposits in the Chinle Formation, which is latest Triassic in age. While theropods had diversified into several specialized groups by this time, Daemonosaurus is a basal theropod that lies outside the clade Neotheropoda. Daemonosaurus is unusual among early theropods in that it had a short skull and long protruding teeth.

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.

Dracovenator

Dracovenator () is a genus of dilophosaurid theropod dinosaur that lived approximately 201 to 199 million years ago during the early part of the Jurassic Period in what is now South Africa. Dracovenator was a medium-sized, moderately-built, ground-dwelling, bipedal carnivore, that could grow up to an estimated 7 m (23.0 ft) long. Its type specimen was based on only a partial skull that was recovered.

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.

Herrerasauridae

Herrerasauridae is a family of carnivorous basal saurischian dinosaurs. They are among the oldest known dinosaurs, first appearing in the fossil record around 233.23 million years ago (Late Triassic), before becoming extinct by the end of the Triassic period. Herrerasaurids were relatively small-sized dinosaurs, normally not more than 4 metres (13 ft) long. The best known representatives of this group are from South America (Brazil, Argentina), where they were first discovered in the 1960s. A nearly complete skeleton of Herrerasaurus ischigulastensis was discovered in the Ischigualasto Formation in San Juan, Argentina, in 1988. Less complete herrerasaurids have been found in North America, and they may have inhabited other continents as well.

Herrerasaurid anatomy is unusual and specialized, and they are not considered to be ancestral to any later dinosaur group. They only superficially resemble theropods and often present a mixture of very primitive and derived traits. The acetabulum is only partly open, and there are only two sacral vertebrae, the lowest number among dinosaurs. The pubic bone has a derived structure, being rotated somewhat posteriorly and folded to create a superficially tetanuran-like terminal expansion, especially prominent in H. ischigulastensis. The hand is primitive in having five metacarpals and the third finger longer than the second, but resembles those of theropods in having only three long fingers, with curved claws. Herrerasaurids also have a hinged mandible, which is also found in theropods.

Kemkemia

Kemkemia is a genus of crocodyliforms living in the Cretaceous, described from a single fossil in 1999 recovered from Morocco by an Italian team searching for fossil invertebrates.

The type species, Kemkemia auditorei, was named and described in 2009 by Italian paleontologists Andrea Cau and Simone Maganuco and is based on a single distal caudal vertebra, MSNM V6408. This vertebra measures 60.48 mm in length and 33.81 mm in height. The genus name refers to the Kem Kem Beds and the specific name honours Italian paleontological illustrator Marco Auditore. The fossil dates from the Cenomanian.

The describers, because of the general morphology of the vertebra, especially the strongly developed neural spine, originally considered it likely that K. auditorei was a theropod dinosaur belonging to the group Neoceratosauria, but in view of the limited remains cautiously assigned it to a more general Neotheropoda incertae sedis. However, the authors later discovered it to be a typical crocodyliform, rather than an unusual theropod.Kemkemia was a predator with a body length of about four to five metres and, given that the vertebra is not very robust, possibly lightly built. The species length could be extrapolated because the specimen is that of an adult. The fossil is one of the few known crocodyliform caudal vertebrae and comes from the Kem Kem Beds that have produced the fossils of very large predatory dinosaur species: Spinosaurus, Carcharodontosaurus and Deltadromeus.

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.

Liliensternus

Liliensternus is an extinct genus of basal Neotheropod dinosaur that lived approximately 210 million years ago during the latter part of the Triassic Period in what is now Germany. Liliensternus was a moderate-sized, bipedal, ground-dwelling carnivore, that could grow up to 5.15 m (16.9 ft) long. It is the best represented Triassic theropod from Europe and one of the largest known.

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.

Orionides

Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.

Tachiraptor

Tachiraptor ("thief of Táchira") is a genus of carnivorous theropod dinosaurs found in the early Jurassic period La Quinta Formation of Venezuela. It includes one species, Tachiraptor admirabilis, described from a fossilized tibia and ischium. They were small bipedal dinosaurs, with a deduced total body length of just over 1.5 m (4.9 ft). They were likely generalist predators, preying on smaller vertebrates like other dinosaurs or lizards.

Tawa hallae

Tawa (named after the Hopi word for the Puebloan sun god) is a genus of theropod dinosaur from the Late Triassic period. The fossil remains of Tawa hallae, the type and only species were found in the Hayden Quarry of Ghost Ranch, New Mexico, US. Its discovery alongside the relatives of Coelophysis and Herrerasaurus supports the hypothesis that the earliest dinosaurs arose in Gondwana during the early Late Triassic period in what is now South America, and radiated from there around the globe. The specific name honours Ruth Hall, founder of the Ghost Ranch Museum of Paleontology.

Zupaysaurus

Zupaysaurus (; "ZOO-pay-SAWR-us") is a genus of early theropod dinosaur living during the Norian stage of the Late Triassic in what is now Argentina. Fossils of the dinosaur were found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina. Although a full skeleton has not yet been discovered, Zupaysaurus can be considered a bipedal predator, up to 4 metres (13 ft) long. It may have had two parallel crests running the length of its snout.

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