Tyrannosauroidea (meaning 'tyrant Lizard forms') is a superfamily of Coelurosaurian Theropod Dinosaurs that includes the family Tyrannosaurids as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent beginning in the Middle Jurassic period. By the end of the Cretaceous period, Tyrannosauroids were the dominant large predators in the Northern Hemisphere, culminating in the gigantic Tyrannosaurus itself. Fossils of Tyrannosauroids have been recovered on what are now the continents of North America, Europe, Asia, and supposedly South America and Australia. They completely died out in the Cretaceous-Paleogene Extinction Event.
Tyrannosauroids were bipedal carnivores, as were most non-Avian Theropods, and were characterized by numerous skeletal features, especially of the skull and pelvis. Early in their existence, Tyrannosauroids were small predators with long, three-fingered forelimbs. Late Cretaceous genera became much larger, including some of the largest land-based predators ever to exist, but most of these later genera had proportionately small forelimbs with only two digits. Primitive feathers have been identified in fossils of two species, and may have been present in all other Tyrannosauroids as well. Prominent bony crests in a variety of shapes and sizes on the skulls of many Tyrannosauroids may have served display functions.