tetanuran

Tetanurae is a clade of theropod dinosaurs within Theropoda, defined as all species more closely related to modern birds than to Ceratosaurus. It includes a vast majority of theropods from the Middle Jurassic onward, spanning a range of forms from large predatory dinosaurs to smaller, agile carnivores, and it ultimately includes birds as the living descendants of this group.

The name means "stiff tail" in reference to tail morphology observed in many early members of the group.

Taxonomically, Tetanurae is divided into two major lineages: Megalosauroidea and Avetheropoda. Avetheropoda further divides into Allosauroidea and Coelurosauria, with the latter comprising tyrannosauroids, ornithomimids, dromaeosaurids, troodontids, and other coelurosaurs. Within Coelurosauria, a branch leads to the lineage that culminates in modern birds.

Birds are living representatives within the broader tetanuran lineage, nested among the coelurosaurians. This places modern avians within the large, diverse radiation of theropod dinosaurs rather than outside it.

The fossil record shows tetanurans from the Early Jurassic onward, with a wide geographic distribution and a variety of body plans and ecological roles. This clade includes some of the most well-known theropods, such as allosaurids and tyrannosaurids, and it encompasses the lineage that ultimately gave rise to birds.