GEOL 104 Dinosaurs: A Natural History

Fall Semester 2000
Thyreophora: Defense, defense, defense


  • Name means "shield bearer"
  • Armored dinosaurs: diagnosed by presence of rows of dermal ossifications
  • Early thyreophorans small (1 m long) bipedal animals; later forms much larger and quadrupedal, with heavier armor

    Early thyreophorans were small bipedal forms, much like an armored Lesothothosaurus. Best known of these is Scutellosaurus.

    Selection could have favored descendnats which were either faster with reduced armor (but there already were such dinosaurs present: ornithopods, for example) OR heavier armor. Result was larger, more heavily armored thyreophorans.

    Best example of these: Scelidosaurus

    Thyreophorans more derived than Scelidosaurus are divided into two major branches, each specializing in a different mode of defense:

    These new forms both appear in the Middle Jurassic, just as more sophisticated predators are appearing.



    Ankylosaurs have been divided into two clades:

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