"Newtonsaurus" is the informal name given to an as yet undescribed genus of dinosaur from the Late Triassic. It was probably a ceratosaur, which lived in what is now the United Kingdom. The type species is "N. cambrensis", originally coined as Zanclodon cambrensis, although it has usually been referred to Megalosaurus, due to the taxonomic difficulties associated with Zanclodon. It is based on a mold of a dentary from Rhaetian-age beds in Wales (hence the species name), and is one of the relatively few dinosaurs known from the time near the Triassic-Jurassic boundary.
Paleontologists have avoided using the name since its appearance in 1999 in private publications, although "Zanclodon" cambrensis or Megalosaurus cambrensis have both been used for this taxon.