Paleontologists have reclassified a decades-old fossil from England’s Isle of Wight as a previously unknown dinosaur, Istiorachis macarthurae, the Natural History Museum in London announced. The herbivore, which lived about 125 million years ago, is distinguished by a series of elongated neural spines that formed a sail along its back. Retired physician and University of Portsmouth doctoral researcher Jeremy Lockwood led the re-examination of the partial skeleton, first unearthed nearly 40 years ago and long thought to belong to one of two known iguanodontian species from the island. Detailed comparisons published in the journal Papers in Palaeontology on 21 August confirmed the fossil’s unique anatomy, prompting its designation as a new species. The animal, named after British solo sailor Ellen MacArthur, is estimated to have stood two metres tall and weighed roughly a metric tonne. Researchers suggest the dramatic sail may have evolved through sexual selection, serving to attract mates or deter rivals, rather than for thermoregulation. The find adds a third iguanodontian species to the Isle of Wight’s Early Cretaceous fauna, underscoring the region’s biodiversity and offering fresh insight into how larger, quadrupedal plant-eaters were adapting their skeletal structures during this period.