New Isle of Wight iguanodontian Istiorachis macarthurae with a sail

A newly identified iguanodontian dinosaur from the Isle of Wight has added a striking feature to the island’s ancient menagerie: a pronounced sail running along its back and tail. The species, named Istiorachis macarthurae, lived about 125 million years ago during the Early Cretaceous and was named in honor of Dame Ellen MacArthur, a famed Isle of Wight sailor who set a solo record for circumnavigating the globe in 2005. The discovery was made by Jeremy Lockwood, a retired general practitioner who is pursuing a PhD with the University of Portsmouth and the Natural History Museum, by reexamining fossils housed at the Dinosaur Isle Museum.

Although the skeleton is not as complete as some finds, its unusually long neural spines stood out upon closer inspection. Researchers concluded that the sail-like structure would have given the animal a prominent back profile, and likely extended along the tail as well. Lockwood explained that the spines were not merely tall but unusually exaggerated for an iguanodontian, a pattern compatible with visual signaling used in displays to attract mates or deter rivals. “Evolution sometimes seems to favour the extravagant over the practical,” he...