Hesperonyx
Hesperonyx is an extinct genus of dryomorphan ornithopod dinosaur from the Late Jurassic Lourinhã Formation of Portugal. The genus contains a single species, Hesperonyx martinhotomasorum, known from bones of the fore- and hindlimbs.
Discovery and naming
The Hesperonyx holotype specimen, Museu [da Lourinhã|ML] 2700, was discovered in 2021 in sediments of the Lourinhã Formation along the beach at Porto Dinheiro. The specimen consists of bones from the left forelimb and hindlimb.In 2024, Rotatori et al. described Hesperonyx martinhotomasorum as a new genus and species of ornithopod dinosaurs based on these fossil remains. The generic name, "Hesperonyx", combines "Hesperus", after the Greek god whose name also references the western direction—referencing the holotype locality in the west region of Portugal—with the Greek suffix "-onyx", meaning "claw". The specific name, "martinhotomasorum", combines the last names of Micael Martinho and Carla Alexandra Tomás, honoring their efforts in fossil curation and preparation at the Museu da Lourinhã.
Description
Hesperonyx is estimated as being long.Classification
Rotatori et al. included Hesperonyx in two phylogenetic analyses, recovering it in contrasting locations within the Dryomorpha. In their parsimony analyses, Hesperonyx was placed as a basal member of the clade of non-dryosaurid dryomorphans. However, in their Bayesian analysis, Hesperonyx was recovered as a basal member of the Dryosauridae. More precise affinities could not be concluded due to the paucity of remains. Their results are displayed in the cladograms below:Topology 1: Parsimony analysis
Topology 2: Bayesian analysis