Compare the pictorial approach to the narrative equivalent below (salient features in color):
Introduction: Primitive trilobites with numerous thoracic segments with spinose tips.
Cephalon: large and semicircular; glabella typically long, well-segmented, tapering or expanding forwards; genal spines typically present, strong, usually continued from a narrow, tubular cephalic border; eyes typically large, crescentic, with large, inflated palpebral lobe ridges running toward front of glabella (anterior of S3); eye ridge may be subdivided; hypostome typically conterminant, very wide rostral plate.
Thorax: with numerous segments (up to 60+), pleurae usually with spinose tips; may be subdivided into prothorax and opisthothorax.
Pygidium: typically tiny (micropygous), one or very few segments.
Occurrence: L. Cambrian to M. Cambrian.
Suborders: Olenellina and Redlichiina.
Walking Trilobite animation ©2000 by S. M. Gon III