GEOL 104 Dinosaurs: A Natural History

Fall Semester 2000
Ornithopoda: Beaks, bills & crests

Ornithopoda:

  • Name means "bird foot"; a bit odd, as their feet aren't really bird-like
  • Specialized jaws:
  • 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.

    Most primitive of ornithopods include Heterodontosauridae:

    More advanced ornithopods share certain synapomorphies:

    The more advanced ornithopods are divided into the (probably paraphyletic) Hypsilophodontia and the larger Iguanodontia

    Hypsilophodonts

    Iguanodonts

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

    Hadrosauriforms:

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

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