Tetanurae

'' Anatomy Tetanurans have two basic skull morphologies. Body Size Basal tetanurans were the first theropods to achieve truly giant body sizes, with both megalosauroid and allosauroid taxa weighing over 1 ton. Coelurosaurian theropods are the notable exception to the pattern of body size increases. ==History of study==

History of classification Tetanurae was recognized and named by Gauthier in 1986. The earliest-discovered non-avian tetanuran is Megalosaurus. Initial cladistics studies supported the arrangement of primitive megalosaurs as serial outgroups to a clade of allosaurids, followed by the Coelurosauria. Subsequent studies have discovered that many of these basal tetanurans formed a true clade, termed Megalosauroidea or alternatively Spinosauroidea. In 2015, Hendrickx, Hartman and Mateus clarified this definition, specifying it as the least inclusive clade including Allosaurus fragilis, Megalosaurus bucklandii, and Passer domesticus. The clade name "Orionides" was first established by Matthew T. Carrano, Roger B. J. Benson and Scott D. Sampson in 2012. It is derived from Orion, the giant hunter of Greek mythology in references to the large size and carnivorism of basal orionidans. The name also refers to the alternative name for the constellation of Orion, Alektropodion, meaning "rooster foot". and was first defined as a clade by Currie and Padian in 1997, to include Allosaurus, modern birds, and other animals descended from their most recent ancestor. In 1999, Paul Sereno named another group, Neotetanurae, for the clade containing Allosauroidea and Coelurosauria, and excluding other tetanurans such as megalosauroids, but this definition was published slightly later. A monophyletic Avetheropoda is recovered in many papers; however, recent findings suggest a monophyletic Carnosauria model with allosauroids and megalosauroids as each other's closest relatives instead of Allosauroids and Coelurosaurs. The cladogram presented below follows a phylogenetic analysis published by Zanno and Makovicky in 2013. }} ==Paleobiology==

Biogeography The biogeographical history of non-avian Tetanurae spans over 110 million years and all continents. The presence of major lineages prior to the breakup of Pangaea implies wide dispersal of these clades, with later absences indicating regional extinctions or dispersal failure. The density of sampling is currently insufficient to provide a detailed analysis of biogeographical evolution for the Tetanurae. Diversity Tetanurae and Ceratosauria likely diverged during the late Triassic, more than 200 mya. By the Early Jurassic, Tetanurae fossils appear in the fossil record and reached global distribution by the Middle Jurassic. In the Late Jurassic, the fossil record demonstrates widespread presence of multiple clades within both megalosauroids and avetheropods. The Megalosauroidea contained high diversity with two Jurassic clades, Piatnitzkysauridae and Megalosauridae, as well as the Cretaceous Spinosauridae. Tetanuran evolution appears to exhibit waves of diversification, although this may be due to uneven sampling. During the Late Jurassic and Early Cretaceous, large spinosaurids and allosaurids flourished, but the latter possibly died out before the end of the Cretaceous due to the Cenomanian-Turonian boundary event, while spinosaurids are known from the Santonian. Soon afterwards the niche of terrestrial apex predator was filled by ceratosaurs and tyrannosaurids, which dominated terminal Cretaceous terrestrial ecosystems. Coelurosaurs persisted through the end of the Mesozoic Era. Modern birds are the only living representatives of the Tetanurae. ==References==