Hypostoma of agnostid trilobites

摘要: The hypostoma, which is a ventral sclerite that covers the oral region, has recently been discovered in four species of agnostid trilobites. discovery significant because suborder Agnostina only major trilobite taxon for hypostoma not described. distinctly different shape from non-agnostid Minus its wings, it widest posteriorly, lacks border furrows, unusually long and some fenestrate. It unattached to other sclerites, presumably was held place beneath anterior part glabella by muscle tissue. Hypostomal differences probably indicate basic food or feeding habits This, along with evidence, suggests divergence mode life these two groups, should be given strong consideration future attempts at classification.