any member of the dinosaur subgroup, Theropoda, that includes all the flesh-eating dinosaurs. Theropods were the most diverse group of saurischian (“lizard-hipped”) dinosaurs, ranging from the crow-sized Microraptor to the huge Tyrannosaurus rex (tyrannosaur), which weighed six tons or more.

Three major theropod groups are generally recognized. Ceratosaurs (dinosaur) were the first and ranged in size from the small Coelophysis to Ceratosaurus, which approached Allosaurus in size. Succeeding the early ceratosaurs were the tetanurans, comprising the carnosaurs (carnosaur) (including Allosaurus) and the coelurosaurs (a larger group that includes Tyrannosaurus (tyrannosaur), dromaeosaurs (dromaeosaur), and Ornithomimus, among others). Coelurosaurs and carnosaurs both had many hollow bones and sharp, recurved teeth along the entire length of their jaws.

Theropod remains have been recovered from all continents except Antarctica and from the Late Triassic (Triassic Period) through the Late Cretaceous periods (Cretaceous Period) (from 227 million to 65 million years ago).