Istiorachis macarthurae

Istiorachis is an extinct genus of iguanodontian ornithopod dinosaur from the Early Cretaceous Wessex Formation of the Isle of Wight, England. The genus contains a single species, Istiorachis macarthurae, known from a partial postcranial skeleton including several vertebrae, incomplete ribs, and part of the pelvis. Its vertebral neural spines are notably elongated, giving the animal a 'sail-backed' appearance.