Article: The armoured dinosaur Polacanthus foxi, from the Lower Cretaceous of the Isle of Wight

A new specimen of the Lower Cretaceous nodosaurid ankylosaur Polacanthus foxi was found in the Wealden formation of the Isle of Wight in 1979. Three types of presacral spine are now recognized and new dermal elements of unknown position were found. Cranial and cervical fragments are described for the first time, including an axis formerly identified by Seeley, 1876, as ?lguanodon. The sacrum shows a widening of the neural canal, as in Stegosaurus and others, and the tail plates differ from those of the holotype. The systematic status of P. foxi is reviewed, and comparisons are made with other contemporary nodosaurid taxa as far as possible. The genus Polacanthus appears to be valid despite suggested synonymy with Hylaeosaurus, it may, however, have closer affinities with comtemporary taxa of the New World, notably Hoplitosaurus. Polacanthus appears to have a greater geological range than Hylaeosaurus.