Thyreophora (thye-ree-OFF-or-ah) is one of three suborders of Ornithischia.
(The other two suborders are: Ornithopoda and Marginocephalia) The Thyreophora
group of dinosaurs is considered to be among the most primitive of ornithischians.
The size of these ornithischians ranged from small to fairly large. They
were mostly quadrupedal (with the exception of more primitive species)
and all possessed body armor. Certain characteristics of the skull, (i.e.
the cheekbone) further distinguish this group from other ornithischians.
Thyreophora is generally broken into two infraorders: the Ankylosauria,
and the Stegosauria.
(Thyreophora also included ceratopsians when the group was originally proposed
in 1915.) The family of Scelidosauridae has been included in the Thyreophora.