Ceratarges spinosus fossil trilobite from the Devonian of Morocco (public display, FMNH PE 60826, Field Museum of Natural History, Chicago, Illinois, USA).
Some polymeroid trilobites evolved extremely spinose bodies, especially odontopleurids and some lichids. Here's an example of a spinose lichid trilobite.
This complete exoskeleton has eight prominent spines. It has two pairs of long, curving cephalic (head) spines - one pair of genal (cheek) spines and one pair extending from the glabella. The eyes are perched atop a pair of stalks that extend posteriorly upward. The pygidium (tail) also has two pairs of long, curving spines - one pair from the anterolateral corners and one pair extending from the posterior pygidial margin, straddling the axis. Series of smaller, straight spines are present between the larger pygidial spine pairs.
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