Megalosauroidea

Megalosauroidea is a clade of carnivorous theropod dinosaurs within the broader clade Tetanurae. The group, named after Megalosaurus, includes Megalosauridae and related genera, but its exact membership varies among phylogenetic studies. As a result, Megalosauroidea is often described as a basal or early-diverging lineage of tetanurans rather than a tightly defined family.

Fossils attributed to Megalosauroidea range from the Middle Jurassic to the Early Cretaceous (approximately 168 to 120 million years ago). Specimens have been found in Europe, Africa, and North America, indicating a wide geographic distribution for early megalosauroids.

The best-known and type genus is Megalosaurus, from Middle Jurassic rocks in England. Afrovenator from Africa is another frequently cited member of Megalosauroidea, and other genera such as Eustreptospondylus have been variably placed within the group, though relationships among these taxa are subject to change with new analyses.

Ecology and morphology of megalaosauroids vary. They were primarily predatory theropods, with sizes ranging from medium to large. As early tetanurans they helped illuminate the early evolutionary history of carnivorous dinosaurs and the distribution of theropod diversity prior to the rise of more derived groups.

In the scientific literature, Megalosauroidea is a source of ongoing taxonomic debate, reflecting broader uncertainties about early tetanuran relationships. Contemporary classifications often treat Megalosauroidea as a basal tetanuran clade that is separate from Allosauroidea and coelurosaur lineages.