#ornithischians

Three Scutellosaurus lawleri waiting out the rain under an old cycadeoid (Early Jurassic Arizona, US)

results of this week's #Paleostream flocking!

this week we sketched Tapejara, Ajkaceratops, Hoplitomeryx, and Protoceratops (i procrasinated on posting whoops)

Comprehensive Dinosaur stats Henderson, D.M. (2026). "200 years of dinosaur discoveries " doi: https://doi.org/10.7717/peerj.21351

As of 2025 ... there are 1,259 reliably known dinosaur species:

428 Ornithischians

366 Sauropodomorphs

465 Theropods

Catch 'em all?

Dinosaur Spicomellus afer, of Middle Jurassic, Morocco!

Initially described and named in 2021 based on a single rib with fused osteoderms, Spicomellus afer set the paleontological community ablaze this past year when more material was found. This new material revealed that the animal would have had a unique array of spines over its body, including extremely elongated neck spines, as well as spines on its tail, making it the oldest known ankylosaur with a tail weapon. Even the original rib that was once Spicomellus’ only known fossil is unique, as its spikes are fused directly to the bone, a trait not known in any other vertebrate. Despite all this prickly, seemingly defensive weaponry, it’s more likely that Spicomellus’ long neck spines evolved for display, similar to the antlers of a deer, with defense being their secondary purpose.

Ankylosaurs are thought to have eventually taken the place of the Jurassic stegosaurs, but the discovery of Spicomellus places the rise of ankylosaurs further back in the Jurassic. In the El Mers III Formation of Middle Jurassic Morocco, Spicomellus would have actually lived alongside at least two stegosaurs: Adratiklit and Thyreosaurus. This indicates that the two major thyreophoran groups (Ankylosauria and Stegosauria) coexisted for more than 20 million years, at least in this locality. Spicomellus would have also encountered the sauropod Turiasauria. Other dinosaurs in this formation have thus far been fragmentary.

Compsognathus longipes is a small theropod known from two skeletons from the Upper Jurassic limestones of Germany and France. The reconstruction is based on a smaller, German specimen. For a long time it was considered the smallest dinosaur, but now smaller taxa are known.

Sinoceratops zhuchengensis is a centrosaurine and currently the only genus of Asian ceratopsids. It is known for partial skulls with unusual collar ornamentation from the Upper Cretaceous of China.

Maiasaura peeblesorum is a hadrosaurid known from more than 200 specimens, including nests with eggs and cubs, from Montana and Alberta. It overturned previous ideas about the parental behavior of dinosaurs.

Hypsilophodon foxii is a small ornithischian known from a variety of specimens from England. It was previously depicted as an arboreal animal, but is now known as a terrestrial, running herbivore.