Tetanurae

Tetanurae, or "stiff tails", is a clade that includes most theropod dinosaurs, as well as birds. Tetanurans (or tetanurines) first appear during the early or middle Jurassic Period.

Definition
Tetanurae meaning "stiff tails", was named by Jacques Gauthier on cladistic grounds in 1986 for a large group of theropod dinosaurs. Gauthier's paper was the first serious application of the science of cladistics to vertebrate paleontology.

Tetanurae are defined as all theropods more closely related to modern birds than to Ceratosaurus (e.g. Padian et al., 1999). Gauthier considered it to consist of Carnosauria and Coelurosauria, although many of what he considered carnosaurs have been regarded as coelurosaurs or basal tetanurans by subsequent workers (but see Rauhut, 2003). Paul Sereno (1999) named Neotetanurae for the node joining Carnosauria (his Allosauroidea) and Coelurosauria, excluding other tetanurans such as megalosauroids. Padian et al. (1999) gave a synonymous definition for Gregory Paul's (1988) Avetheropoda, but this definition was published slightly later.

Range
It is not entirely clear where the origins of Tetanurae are. Cryolophosaurus has been claimed as the first true member of the group (although this identification has been disputed and Cryolophosaurus now appears to be closer to the dilophosaurids). Even if Cryolophosaurus was a tetanuran, this leaves no true tetanuran fossils from the Triassic, when the group should have originated based on the presence of coelophysoids (if the old definition of Ceratosauria is used). This gives heavier validity to the more recent view of tetanurans and ceratosaurs sharing a common ancestor and forming a clade of advanced theropods together.

Large, predatory spinosaurids and allosaurids flourished during the Late Jurassic and Early Cretaceous, especially in Gondwana, but seem to have died out before the end of the Cretaceous, possibly due to competition from abelisaurid ceratosaurs and tyrannosaurid coelurosaurs. The diverse coelurosaurs persisted until the end of the Mesozoic Era, when all except for crown clade avians died out. Modern birds are the only living representatives of the clade Tetanurae.