Hypselospinus — an Early Cretaceous iguanodontian dinosaur

Discovery and naming

The species was first described in 1889 by the British palaeontologist Richard Lydekker, who assigned the material to Iguanodon. The specific name honoured the geologist William Henry Fitton. Later workers examined the anatomy in more detail and identified traits that justified erection or resurrection of a separate genus; the name Hypselospinus refers to the relatively high neural spines on some dorsal vertebrae.

Anatomy and distinguishing features

Known elements include parts of the vertebral column, limb bones and portions of the pelvis. Hypselospinus is notable for taller-than-usual dorsal neural spines compared with many iguanodontians, a generally lighter limb build and proportions that suggest a combination of bipedal and quadrupedal capabilities. Dentition and jaw structure indicate processing of plant material, consistent with a bulk-feeding herbivore that possessed tooth batteries capable of grinding vegetation.

Palaeoenvironment and behaviour

Fossils come from Wealden Group sediments deposited in fluvial, floodplain and lacustrine settings. The environment supported diverse plant communities and a range of dinosaurs, including other ornithopods, stegosaurs and theropods. Hypselospinus likely fed on low-growing vegetation and may have adopted a facultatively quadrupedal stance when feeding or moving slowly, switching to bipedal locomotion for faster travel.

Classification and significance

Within Ornithopoda, Hypselospinus is placed among iguanodontian-grade ornithopods, a group that shows transitional features between basal bipedal ornithopods and the later, more derived hadrosaurids. Its recognition as distinct from Iguanodon highlights the diversity of Early Cretaceous European ornithopods and informs studies of their evolution. For broader context on ornithopod evolution see general summaries here and taxonomic reviews here.