Paul Barrett

Abstract The armoured ankylosaurian dinosaurs are best known from Late Cretaceous Northern Hemisphere ecosystems, but their early evolution in the Early–Middle Jurassic is shrouded in mystery due to a poor fossil record1,2. Spicomellus afer was suggested to be the world’s oldest ankylosaur and the first from Africa, but was based on only a single partial rib from the Middle Jurassic of Morocco3.

Abstract Ornithopod dinosaurs evolved numerous craniodental innovations related to herbivory. Nonetheless, the relationship between occlusion, tooth wear rate, and tooth replacement rate has been neglected. Here, we reconstruct tooth wear rates by measuring tooth replacement rates and tooth wear volumes, and document their dental microwear.

Description Morphotype B crowns (37 in total) are grouped together by the machine learning analysis but show considerable variation in denticle size differences between carinae, hence might encompass several different subgroups with broadly similar morphology. Tooth crowns are ziphodont, slightly larger than morphotype A (CH ranging from 1.66 mm to 19 mm) and have a straight to concave distal margin.