Infraorder5 species
Ankylosauria
Heavily armored quadrupedal ornithischians protected by osteoderms and tail clubs.
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Modern vertebrate paleontology categorizes dinosaurs through cladistics—grouping organisms based on shared derived anatomical characteristics (synapomorphies) rather than arbitrary phenotypic resemblances.
Ancestrally defined by a forward-pointing pubis bone. Saurischians encompass the bipedal, primarily carnivorous Theropoda (including modern avian descendants) and the gargantuan, long-necked herbivorous Sauropodomorpha.
Characterized by a pelvis where the pubis points backward parallel to the ischium, and the unique predentary bone in the lower jaw. Completely herbivorous, giving rise to armored, horned, and duck-billed lineages.
Heavily armored quadrupedal ornithischians protected by osteoderms and tail clubs.
Ornithischian dinosaurs characterized by beaks, rostral bones, facial horns, and elaborate neck frills.
Beaked, bipedal and facultatively quadrupedal herbivores with complex multi-layered dental batteries.
Bipedal ornithischians with extremely thickened skull domes reinforced by dense cortical bone.
Herbivorous saurischians characterized by elongated necks, columnar limbs, and enormous body volumes.
Quadrupedal herbivores distinguished by two rows of alternating dorsal plates and caudal tail spikes (thagomizers).
Bipedal saurischian dinosaurs, historically dominated by carnivores and including the avian lineage.