''Hesperonyx'' (meaning "western claw") is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus of

dryomorpha Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively sm ...

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively sm ...

dinosaur from the

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

Lourinhã Formation The Lourinhã Formation () is a fossil-rich geological formation in western Portugal, named for the municipality of Lourinhã. The formation is mostly Late Jurassic in age (Kimmeridgian/Tithonian), with the top of the formation extending into the ...

of Portugal. The genus contains a single species, ''Hesperonyx martinhotomasorum'', known from bones of the fore- and hindlimbs.

Discovery and naming

The ''Hesperonyx''

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen, ML 2700, was discovered in 2021 in sediments of the Lourinhã Formation (Porto Novo Member) along the beach at Porto Dinheiro. The specimen consists of bones from the left forelimb (a hand

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or Arthro ...

, ulnare, and partial

metacarpal In human anatomy, the metacarpal bones or metacarpus, also known as the "palm bones", are the appendicular bones that form the intermediate part of the hand between the phalanges (fingers) and the carpal bones ( wrist bones), which articulate ...

) and hindlimb (the

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

fibula The fibula (: fibulae or fibulas) or calf bone is a leg bone on the lateral side of the tibia, to which it is connected above and below. It is the smaller of the two bones and, in proportion to its length, the most slender of all the long bones. ...

, most of

metatarsal The metatarsal bones or metatarsus (: metatarsi) are a group of five long bones in the midfoot, located between the tarsal bones (which form the heel and the ankle) and the phalanges ( toes). Lacking individual names, the metatarsal bones are ...

s I–IV, remains of five

phalanges The phalanges (: phalanx ) are digit (anatomy), digital bones in the hands and foot, feet of most vertebrates. In primates, the Thumb, thumbs and Hallux, big toes have two phalanges while the other Digit (anatomy), digits have three phalanges. ...

, and three toe claws). 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 In Greek mythology, Hesperus (; ) is the Evening Star, the planet Venus in the evening. A son of the dawn goddess Eos ( Roman Aurora), he is the half-brother of her other son, Phosphorus (also called Eosphorus; the "Morning Star"). Hesperus' Rom ...

" (or the "Evening Star"), after the

Greek god In ancient Greece, deities were regarded as immortal, anthropomorphic, and powerful. They were conceived of as individual persons, rather than abstract concepts or notions, and were described as being similar to humans in appearance, albeit larg ...

whose name also references the western direction—referencing the holotype locality in the west region of Portugal—with the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

suffix "-onyx", meaning "claw". The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, "''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. (2024) included ''Hesperonyx'' in two

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

, recovering it in contrasting locations within the

Dryomorpha Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively sm ...

. In their parsimony analyses (both with equal and implied weighting), ''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

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

s below: Topology 1: Parsimony analysis (equal weighting) Topology 2: Bayesian analysis

Paleoenvironment

The Lourinhã Formation is one of the major fossiliferous formations of Portugal, preserving many species of dinosaurs, some of which are also known from the contemporaneous

Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...

of North America. ''Hesperonyx'' is the third named iguanodontian known from this formation, after ''

Draconyx ''Draconyx'' (meaning "dragon claw") is a genus of dinosaur from the Late Jurassic. It was an Ornithopoda, ornithopod which lived in what is now Portugal and was a herbivore. It was found in the Lourinhã Formation in 1991, and described by Oct� ...

'' and '' Eousdryosaurus''.

References

{{taxonbar, from1=Q124975016 Ornithopoda Dinosaur genera Kimmeridgian dinosaurs Lourinhã Formation Taxa named by Octávio Mateus Fossil taxa described in 2024 Dinosaurs of Portugal