GEOL 104 Dinosaurs: A Natural History

Fall Semester 2006
Ornithopoda: Beaks, bills & crests


  • Name means "bird foot"; a bit odd, as their feet aren't really bird-like
  • Specialized jaws:
  • Reduced antorbital and mandibular fenestrae
  • An elongate prepubic process (a forward-projection of the pubis, also seen in ceratopsids)
  • Early ornithopods small (1 m long) bipedal animals; later forms increase in size and retain bipedality, but develop more sophisticated chewing jaws

    Ornithopods and marginocephalians are sister taxa within Ornithischia: both have gap between premaxillary and maxillary teeth and enlarged predentaries, among other features. This distinguishes them from primitive ornithischians (e.g., Pisanosaurus, Lesothosaurus) and thyreophorans.

    Many bipedal ornithischians (Lesothosaurus, Scutellosaurus, heterodontosaurids, psittacosaurids, pachycepholosaurs) were once placed in Ornithopoda, but this was mostly because of the primitive retention of a bipedal gait.

    Ornithopods include a series of primitive forms (which some have grouped into Hypsilophodontia: almost certainly a paraphyletic series) and the larger Iguanodontia



    The larger and more specialized iguanodonts form a clade, Hadrosauriformes:


    Hadrosaurids, or "duckbills": Hadrosaurids are divided into two main clades:

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    Last modified: 11 January 2007