A new dryosaurid ornithopod (Dinosauria, Ornithischia) from the Late Jurassic of Portugal

ABSTRACTA new dryosaurid ornithopod, <i>Eousdryosaurus nanohallucis</i>, gen. et sp. nov., is described here based on a single specimen from the Late Jurassic Alcobaça Formation of Portugal. <i>Eousdryosaurus nanohallucis</i> is distinguished from all other dryosaurids by eight autapomorphic features and an unique combination of characters, some of which are also shared by other dryosaurids. <i>Eousdryosaurus</i> is linked with Dryosauridae, because the fourth trochanter is proximally placed and widely separated from the scar for the insertion of the M. caudifemoralis longus, which is restricted to the medial surface of the femoral shaft. Phylogenetic analysis nests <i>Eousdryosaurus</i> in an unresolved polytomy at the base of Dryosauridae together with <i>Callovosaurus</i>, <i>Dryosaurus</i>, and <i>Kangnasaurus</i>. The complete pes of <i>Eousdryosaurus</i>, which has a phalangeal formula of 1-3-4-5-0, supports the putative autapomorphic reduction of the dryosaurid pes that also occurs in parallel in more derived ornithopods.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP