Dominant land vertebrates during the MesozoicDisplay a trend towards bipedalism – 2 footed locomotionForelimbs tend to be reduced and hindlimbs are drawn under the body to become the major weight bearing and locomotor appendages
Skull is diapsidThere is an additional fenestra – antorbital fenestra – large mandibular foramen opening in the skull in front of the eye that distinguishes archosaurs
THECODONT Gave rise to all later archosaurs Named because their teeth are set in deep sockets Stem archosaurs
DINOSAURS! One of the most successful groups of animals (in terms of longevity) that have ever lived, evolved into many diverse sizes and shapes, with many equally diverse modes of living. Contains two major groups of dinosaurs: the Ornithischia, or "bird-hipped" dinosaurs, and the Saurischia, or "lizard-hipped" dinosaurs.
SAURISCHIAReptilian pelvisSwift predatory carnivoresThe three bones of the pelvis – ilium, ischium, pubis– radiate outward from the center of the pelvis
ORNITHISCHIANS Pelvis similar of that of birds Herbivores. Lack teeth Some had horny beaks Some small unidentified bipedal ornithischian is thought to have given rise to birds The ischium and part of the pubis lie parallel and project backward toward the tail
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