Theropoda ( or , from Greek wild beast and foot) or Theropods () are a group of saurischian dinosaurs. Theropods were ancestrally carnivorous, although a number of theropod groups evolved herbivory, omnivory, piscivory, and insectivory. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago (Ma) and included the sole large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by 10,000 living species.