Pictorial Guide to the Trilobite Superfamily Cyclopygoidea (Asaphida)

PICTORIAL GUIDE
TO THE ORDER ASAPHIDA
Last revised 24 December 2004 by S.M.Gon III

ORDER ASAPHIDA
    Superfamily Anomocaroidea
    Superfamily Asaphoidea
    Superfamily Cyclopygoidea
    Superfamily Trinucleioidea
    Superfamily Dikelokephaloidea
    Superfamily Remopleuridoidea

Superfamily Cyclopygoidea
diagnostic characters boldfaced

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Here are two representative Cyclopygoidea:

Cyclopyge	Nileus

Compare the pictorial approach above to the narrative equivalent below (salient features in color):

Superfamily Cyclopygoidea
Cephalon: with glabella expanding forward to anterior margin, effaced in later cyclopygids, may be fused with occipital ring; fixigenae reduced (except in primitive Taihungshaniidae), palpebral lobes lack distinct rims, and contact axial furrows at anterior ends, librigenae fused or separated by anterior median suture; hypostome relatively transverse, impendent, often with tripartite posterior margin; eye various sized (may be hypertrophied and convex (Cyclopyge), typically closely adjoined to glabella.
Thorax: 5-8(9?) segments.
Pygidium: medium to large (subisopygous in Nileidae), axis usually with 2-5 rings (but up to 20+ in advanced Taihungshaniidae), may be smooth, or with indistinct furrows.
Families: Cyclopygidae, Nileidae, Taishunghaniidae
Representative Genera: Cyclopyge, Nileus, Taihungshania.

Order Asaphida is comprised of Six Superfamilies:

*Anomocaroidea*	*Asaphoidea*	*Cyclopygoidea*	*Trinucleioidea*	*Dikelokephaloidea*	*Remopleuridoidea*

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