Hesperonyx

Say it: hess-per-ON-ix

Name means: “western claw”1

Ate: PlantsBeaked plant-eatersLate Jurassic

Hesperonyx was a small, plant-eating dinosaur that lived in what is now Portugal during the Late Jurassic. It walked on two legs and used its beak to nibble on plants. Scientists know it from just a few leg and hand bones found on a beach.1 2

Lived

152 to 149 million years ago4

Late Jurassic

Fossils found in

Porto Dinheiro Beach, Lourinhã, Portugal1 2

Food

Plants3

Length

3 to 4 m2

estimated for the holotype specimen

When did it live?

Triassic

Jurassic

Cretaceous

252 million years ago20114566, the asteroid

How big was it?

How long was it?

as long as 4 dogs nose to tailas long as 22 bananas end to end

How big was Hesperonyx compared to YOU?

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cool stuff

Fun facts

Hesperonyx lived about 152 to 149 million years ago, during the Kimmeridgian stage of the Late Jurassic.3

Its name means 'western claw' because it was found in the western region of Portugal and its fossils include a claw.1

The only known skeleton, called ML 2700, includes bones from the left forelimb and hindlimb, such as a hand claw, shin bone, and foot bones.1

Hesperonyx was a dryomorphan, a group of plant-eating dinosaurs that are close relatives of the larger iguanodonts.3

The fossils were found in 2021 during a joint field season by FCT NOVA and Museu da Lourinhã.2

It lived in a warm, seasonal climate with rivers and floodplains, alongside other dinosaurs like Draconyx and Eousdryosaurus.2

Hesperonyx had a reduced first toe (metatarsal I), which is unusual and helps scientists tell it apart from other dinosaurs.2

AI-made picture of Hesperonyx — An AI-made picture of how Hesperonyx might have looked, made by a computer from what scientists know. It is a guess: the real animal may have looked different, and nobody knows its true colours.

you asked

Most asked questions about Hesperonyx

?How big was Hesperonyx?

About 3 to 4 metres (9.8 to 13.1 feet) long, which is roughly the size of a small car.1 2

?What did Hesperonyx eat?

It was a plant-eater (herbivore) that used its beak to nibble on plants.4

?When did Hesperonyx live?

It lived about 152 to 149 million years ago, during the Kimmeridgian stage of the Late Jurassic.1 2

?Is Hesperonyx a dinosaur?

Yes, it is a dryomorphan ornithopod dinosaur, a type of plant-eating dinosaur that walked on two legs.1 4

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For dino experts

Scientific name: Hesperonyx
Named by: Rotatori et al. 20244
Group: Beaked plant-eaters
Family / clade: Dryomorpha4
Classification: Ornithischia > Ornithopoda > Iguanodontia4
Age of the rocks: 152 to 149 million years (Kimmeridgian)4
Rock formations: Lourinhã4
Countries: Portugal4
Fossil records: 1 in the Paleobiology Database4
Discovery: Hesperonyx was named in 2024 by Rotatori and colleagues. The fossils were found in 2021 on Porto Dinheiro Beach in Portugal by a team from FCT NOVA and Museu da Lourinhã.1 2
Still debated: Scientists are not sure exactly where Hesperonyx fits in the dinosaur family tree. It is definitely a dryomorphan, but its exact relationships are still debated.2

Where the facts come from

Hesperonyx (en.wikipedia.org)
An unexpected early-diverging iguanodontian dinosaur (Ornithischia, Ornithopoda) from the Upper Jura (docentes.fct.unl.pt)
PBDB Taxon (paleobiodb.org)
Hesperonyx in The Paleobiology Database (CC BY 4.0): age, places, rock formations, classification.

Every fact on this page has a number that points to its source. If we got something wrong, sorry, we are dino fans, not a science journal. Tell us at [email protected] and we will fix it.

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