FIGURE 3 in Phylogenetic analysis and revision of the trilobite subfamily Balnibarbiinae (Olenidae)

FIGURE 3. Size of preglabellar field relative to glabella in subspecies of Balnibarbi erugata and Cloacaspis ceryx. Arrow points to PMO-NF-227.730. Differences in relative length of preglabellar field are not correlated with overall size of the cranidium, and are thus not due to allometry. However, while subspecies of Balnibarbi erugata overlap in cranidial length, all measured specimens of C. ceryx anataphra are smaller than those of C. ceryx ceryx. Since these subspecies also differ in expression of surface granulation, it is possible that expression of granulation is related to size.