Peronopsis vs Agnostus

Peronopsis is a genus of small, blind agnostid trilobites from the Cambrian Period. It had an isopygous body plan, meaning the cephalon and pygidium were broadly similar in size, and its body was divided into a limited number of segments compared with many other trilobites. Peronopsis fossils are widely distributed and are used in biostratigraphy, the correlation and relative dating of sedimentary...

Agnostus is a genus of small Cambrian agnostid trilobites. Members typically had a compact body with head and tail shields that were similar in size and outline, and many species were blind or had highly reduced eyes. Agnostus fossils occur in Cambrian marine rocks on several continents, and some species are important biostratigraphic index fossils because their ranges can help correlate rock laye...