Practice question

Trilobites dominated Paleozoic marine ecosystems, diversifying explosively during Cambrian period alongside first appearance of biomineralized skeletons and complex eyes, reaching peak diversity and abundance in Ordovician seas as predators, scavengers and deposit feeders. Their calcitic compound eyes with schizochroal or holochroal lenses exemplify early vision. By Silurian decline began due to competition and predation. Mesozoic era dominated by dinosaurs, mammals radiated in Cenozoic, Jurassic noted for dinosaur diversification. Cambrian and Ordovician interval therefore represents acme of trilobite ecological success, biozonation and stratigraphic correlation utility.