last revised 05 August 2007 by S. M. Gon III

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Suborder Phacopina
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Here are some representative members of Suborder Phacopina:

Acastoides Pennaia Asteropyge Dalmanites Huntoniatonia Phacops

Compare the above pictorial approach to the purely narrative description here:
Suborder Phacopina
Cephalon: proparian sutures (sometimes fused), schizochroal eyes; glabella expands forwards; librigena typically yoked as single piece; hypostome conterminant to impendent, some with no rostral plate; some with genal spines.
Thorax: 10 to (typically) 11 segments, pleurae furrowed, articulating facets distinct, rounded, angular, or spinose tips.
Pygidium: typically smaller than cephalon (but subisopygous in Dalmanitoidea and Acastoidea), smooth or spinose.
Superfamilies: Phacopoidea, Dalmanitoidea, Acastoidea

Characterizations of the three Phacopine superfamilies:

Superfamily Phacopoidea
Cephalon: generally with strongly divergent axial furrows (glabella greatly expanding anteriorly), anterior glabellar lobes fused into single anterior tri-composite lobe, frontal area generally lacking (obliterated by large glabella), eyes (when present) typically anterior; genal angle typically rounded, without genal spines (exceptions among Pterygometopidae), vincular furrow generally present.
Thorax: variable, but often with rounded tips.
Pygidium: typically micropygous (Phacopidae) to subisopygous (some Pterygometopidae), not spinose.
Families: Phacopidae, Pterygometopidae
Genera: Ductina, Kainops, Phacops, Pterygometopus, Reedops,

Superfamily Dalmanitoidea
Cephalon: typically bearing genal spines, generally with well-developed preglabellar field, median region of glabella bearing muscle scars; eyes tend to mesial or posterior, true vincular furrows lacking.
Thorax: variable, but often with spinose tips.
Pygidium: typically subisopygous, often spinose (terminal or marginal spines); axial rings of consistent depth along length of pygidial axis, axial furrows with simple and consistent convergence angle.
Families: Dalmanitidae, Diaphanometopidae, Prosopiscidae
Genera: Dalmanites, Diaphanometopus, Huntoniatonia, Odontocephalus, Odontochile, Prosopiscus

Superfamily Acastoidea
Cephalon: axial furrows slightly to moderately divergent, anterior glabellar lobes and furrows usually not fused (although furrows may be indistinct), eyes typically distant from posterior border furrows, but not strongly anterior; frontal glabellar lobe auxilliary impression system triangular in outline, maximum width of glabella adjacent to preglabellar furrow, median region of glabella devoid of muscle scars; cephalic margin "shouldered," laterally convex course of genal margin topographically distinct from curvature of axial margin
Thorax: pleural endings blunt, rounded, or angular, sometimes spinose.
Pygidium: micropygous to subisopygous, sometimes spinose (expressed as marginal spines), pygidial axis with deep, apodemal anterior ring furrows, with abrupt transition to shallow posterior ring furrows; coincident decrease in angle of axial furrow convergence.
Other: often similar in general body form to Phacopoidea via convergent evolution, but glabellar and other differences as noted above.
Families: Acastidae, Calmoniidae.
Genera: Acaste, Acastoides, Asteropyge, Comura, Calmonia, Greenops, Metacanthina, Metacryphaeus, Pennaia, Phacopina, Psychopyge, Treveropyge

PHACOPIDA includes three Suborders


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