| Duriavenator Temporal range: Bajocian
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| Reconstruction of the skull with holotype elements shown in white | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Megalosauridae |
| Subfamily: | †Megalosaurinae |
| Genus: | †Duriavenator Benson, 2008 |
| Species: | †D. hesperis
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| Binomial name | |
| †Duriavenator hesperis (Waldman, 1974)
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| Synonyms | |
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Duriavenator is a genus of theropod dinosaur that lived in what is now England during the Middle Jurassic, about 168 million years ago. In 1882, upper and lower jaw bones of a dinosaur were collected near Sherborne in Dorset, and Richard Owen considered the fossils to belong to the species Megalosaurus bucklandii, the first named non-bird dinosaur. By 1964, the specimen was recognised as belonging to a different species, and in 1974 it was described as a new species of Megalosaurus, M. hesperis; the specific name means 'the West' or 'western'. Later researchers questioned whether the species belonged to Megalosaurus, in which many fragmentary theropods from around the world had historically been placed. After examining the taxonomic issues surrounding Megalosaurus, Roger B. J. Benson moved M. hesperis to its own genus in 2008, Duriavenator; this name means "Dorset hunter".
Estimated to have been 5–7 m (16–23 ft) long and weighed 1 t (2,200 lb), Duriavenator has been described as a medium-sized theropod. Duriavenator is distinct in features of the maxilla, the main bone of the upper jaw; it has a deep groove on the upper surface of the jugal process with numerous pneumatic (air-filled) foramina (openings), and small foramina on the lower part of the surface that connected with the premaxilla, the front bone of the upper jaw. It had about four teeth in the premaxilla, about 14–16 in the maxilla behind, and about 14–15 in the dentary of the lower jaw. While its classification was long uncertain, phylogenetic analyses in 2010 and onwards have shown it to be among the oldest tetanuran theropods (a diverse group that includes modern birds), and to belong in the family Megalosauridae. The long teeth at the front of the lower jaw may have been used for plucking and grasping during feeding. Duriavenator is known from the Upper Inferior Oolite Formation which is Bajocian in age, a stage in the Middle Jurassic.