PICTORIAL GUIDE
TO THE ORDER CORYNEXOCHIDA
Last revised 13 May 2006 by S.M.Gon III


ORDER CORYNEXOCHIDA
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Compare the pictorial approach above to the narrative below:

ORDER CORYNEXOCHIDA

Cephalon: with opisthoparian sutures; glabella elongate, sides often concave (pestle-shaped), furrows (when not effaced) typically with splayed arrangement, the hind pair pointing sharply backwards, and anterior pairs tending more and more forward directed; sometimes furrows pit-like; cranidial borders often ledgelike; hypostome conterminant or (in derived forms) impendent; eyes typically large, in some gently arcuate.
Thorax: typically with 7-8 segments (but range for order is 2-12, rarely to 18 in primitive genera), pleural tips often spinose.
Pygidium: typically large (isopygous or subisopygous), of variable form, some spinose.
Other: larvae (metaprotaspis) hexagonal, with anterior pits, glabella expanding forward, posterior spines.
Occurrence: Lower Cambrian – Middle Devonian
Suborders: Corynexochina, Illaenina, Leiostegiina 

CORYNEXOCHIDA includes three Suborders

Corynexochina

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Illaenina

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Leiostegiina

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Walking Trilobite animation ©2000 by S. M. Gon III