Genasauria show derived ornithchain characteristics and the mark the evolutionary split of the ornithchia into cerapoda and thyreophora. The derived characteristics of genasauria (which are all displayed in stegosaurs ) are, they all have muscular cheeks (as indicated by the position of the tooth rows away from the sides of the face ); a snout-shaped front to the mandibles and reduction in the size of the opening on the outside of the lower jaw (the external manibular foramen).

general dinosaur anatomy

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