Ok. Hi again. So trilobite has tons of species and stuff so do you think this is enough? Do I have list some order/family?
Trilobites range from the Cambrian to the Permian. Next to ostracodes they are the most common arthropod fossil. Trilobite means three-lobed and refers to the three longitudinal divisions of their calcified exoskeleton. An axial lobe running down the center is attached to pleural lobes on either side. The head or chephalon is separated from the tail or pygidium by thorasic segments. As juveniles, trilobites were pelagic, swimming in the plankton. As adults, most trilobites were benthic detritus feeders, although there are some exceptions such as the agnostids, which are thought to have lived a pelagic life due to their world-wide distribution. Trilobites were one of the first organisms to have eyes and may have been the first with eyes that focused images. Many trilobite species lost their eyes through selection such as the agnositds and Cryptolithus.
Trilobites have compound eyes made of calcite crystals. Two important types of compound eye can be found in trilobites. Holochroal eyes consisted of hundreds (up to 15,000) of closely packed elongated prisms of calcite arranged in a hexagonal pattern. The lenses of these eyes must be viewed with the aid of magnification. Holochroal eyes produced composite images of the world, but with little resolution. Phacops trilobites possessed schizochroal eyes. Schizochroal eyes are made of larger spherical-shaped lenses numbering in the hundreds (up to 700) and separated by exoskeleton. Each lens is made of two calcite crystals arranged as a doublet lens. Ironically, the doublet lens was designed by Dutch scientist Christian Huygens (1629-1695) and the French philosopher Rene Descartes (1586-1650) to correct for spherical aberration. Through selection nature had anticipated the same design 400 million years earlier. The phacopid lens produced larger images bringing them into sharp focus.
Trilobites enjoyed a great adaptive radiation during the Cambrian reaching their peak in abundance and diversity. In fact, Trilobites are the biostratigraphic standard for the Cambrian. They declined during the Ordovician and were only a minor part of the seafloor fauna in the Silurian and Devonian. Trilobites did enjoy some increase in diversity during the Devonian; however, they never fully recovered from the late Devonian extinction event and vanished during the Permian
Edit oh wait oops I didn’t look at the list carefully but should I include as overview then put specific info on the genuses on the list? Are they like going to also test like the overall ones on the list or just the specific ones? Sorry for so many questions...
