Introduction: typically spiny with densely granulate or tuberculate
Cephalon: opisthoparian sutures; glabella broad, large, extending
to anterior border, lobation simple (Odontopleuroidea) to complex, with
fused lateral and glabellar lobes (Lichoidea); eyes typically present,
holochroal, usually not large; conterminant hypostome.
Thorax: variable, 8-13 segments, usually spine-tipped, sometimes
with distinctive spines (e.g., Odontopleuroidea).
Pygidium: typically isopygous to macropygous, but sometimes
short (e.g., Odontopleuroidea), often longer than wide, often with
3 pairs of furrowed pleurae, typically ending in spinose tips.
Occurrence: Ordovician (Tremadoc) to Devonian (Frasnian)
Superfamilies: Lichoidea, Odontopleuroidea, Dameselloidea