Magnosaurus (meaning 'large lizard') was a genus of theropod dinosaur from the Middle Jurassic of England.

In 1923, Friedrich von Huene named Megalosaurus nethercombensis from a partial skeleton (OUM J12143) from the Bajocian age[1] Middle Jurassic Inferior Oolite, found in the nineteenth century by W. Parker near Nethercomb, north of Sherborne, in Dorset, England.

[9][10][11] A detailed redescription by Roger Benson in 2010 concluded Magnosaurus was valid taxon, a megalosaurid megalosauroid, and at about 175 million years old the oldest certain known member of the Tetanurae.

In such cases the combinations are: Because the remains are sparse and fragmentary, most details about its anatomical features are unknown.

[10] Benson however, in 2010 gave a higher estimation of about half a tonne; the animal would have stood at over a metre at the hip.