Tetanurae

Tetanurans Temporal range: Early Jurassic–Present, 201–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Six tetanurans (top left to bottom right): Monolophosaurus in combat with the stegosaur Tuojiangosaurus, Allosaurus, Deinocheirus, Spinosaurus, Sciurumimus, and an emu
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Clade:	Neotheropoda
Clade:	Averostra
Clade:	Tetanurae Gauthier, 1986
Subgroups
†Chilesaurus? †Chuandongocoelurus? †Cryolophosaurus? †Dandakosaurus? †Kayentavenator †Kaijiangosaurus †Monolophosaurus †Pandoravenator †Sinosaurus? †Vectaerovenator Orionides Carrano et al., 2012 †Megalosauroidea? (possibly paraphyletic) Avetheropoda Paul, 1988 †Carnosauria Coelurosauria Tetanurans of uncertain affinity †Altispinax †Chilantaisaurus †Cruxicheiros †Datanglong †Gasosaurus †Juravenator †Lourinhanosaurus †Scipionyx †Sciurumimus †Siamotyrannus †Siats †Ulughbegsaurus †Megaraptora †Piatnitzkysauridae
Synonyms
Avetheropoda? Paul, 1988 Avipoda Novas, 1992 Neotetanurae? Sereno, 1999 Orionides? Carrano et al., 2012

Tetanurae (/ˌtɛtəˈnjuːriː/ or "stiff tails") is a clade that includes most theropod dinosaurs, including megalosauroids, allosauroids, and coelurosaurs (which includes tyrannosauroids, ornithomimosaurs, compsognathids and maniraptorans, the latter including living birds).^[1] Tetanurans are defined as all theropods more closely related to modern birds than to Ceratosaurus and contain the majority of predatory dinosaur diversity.^[2] Tetanurae likely diverged from its sister group, Ceratosauria, during the late Triassic.^[3] Tetanurae first appeared in the fossil record by the Early Jurassic about 190 mya and by the Middle Jurassic had become globally distributed.^[2]

The group was named by Jacques Gauthier in 1986 and originally had two main subgroups: Carnosauria and Coelurosauria, the clade containing birds and related dinosaurs such as compsognathids, tyrannosaurids, ornithomimosaurs, and maniraptorans.^[4] The original Carnosauria was a polyphyletic group including any large carnivorous theropod.^[5] Many of Gauthier's carnosaurs, such as tyrannosaurids, have since been re-classified as coelurosaurs or primitive tetanurans.^[2] Carnosauria has been reclassified as a group containing allosaurids that split from the Coelurosauria at the Neotetanurae/Avetheropoda node.^[2] Members of Megalosauroidea are believed to represent basal tetanurans, but recent discoveries have shown that they might be members of Carnosauria expanding Carnosauria back to its original meaning.^[2] It is however agreed that Megalosauroids, Allosauroids and Coelurosaurians are all members of the Orionides, a subset within Tetanurae that contains dinosaurs more derived than animals such as Chuandongcoelurus and Kayentavenator.

Tetanuran evolution was characterized by parallel diversification of multiple lineages, repeatedly attaining large body size and similar locomotor morphology.^[2] Cryolophosaurus has been claimed as the first true member of the group, but subsequent studies have disagreed on whether it is a dilophosaurid or tetanuran.^[2][6] Arcucci and Coria (2003) classified Zupaysaurus as an early tetanuran,^[7] but it was later placed as a sister taxon to the clade containing dilophosaurids, ceratosaurs, and tetanurans.^[8]

Shared tetanuran features include a ribcage indicating a sophisticated air-sac-ventilated lung system similar to that in modern birds.^[5][9] This character would have been accompanied by an advanced circulatory system.^[5][9] Other tetanuran characterizing features include the absence of the fourth digit of the hand, placement of the maxillary teeth anterior to the orbit, a strap-like scapula, maxillary fenestrae, and stiffened tails.^[3][5][9] During the Late Jurassic and Early Cretaceous, large spinosaurids and allosaurs flourished but possibly died out in the northern hemisphere before the end of the Cretaceous, and were replaced as apex predators by tyrannosauroid coelurosaurs.^[10] At least in South America, carcharodontosaurid allosaurs may have persisted until the end of the Mesozoic Era, and died out at the same time as the non-avian coelurosaurs.^[11][12]