Trilobata

Trilobata is a proposed phylum of extinct marine arthropods. The name itself is derived from the Greek "tri" meaning three and "lobos" meaning lobe, referring to the three longitudinal lobes that divide the body of many trilobites. These ancient creatures lived from the early Cambrian period, about 521 million years ago, to the end of the Permian period, around 252 million years ago, and are a significant part of the fossil record.

The body of a trilobite was divided into three distinct tagmata: the head (cephalon), the thorax, and the tail (pygidium). The cephalon often bore a pair of compound eyes, and typically had antennae. The thorax was segmented and could be flexible, allowing some trilobites to enroll into a ball for protection. The pygidium was a fused section at the posterior end.

Trilobites exhibited a wide range of diversity in size, shape, and features, occupying various ecological niches. They are thought to have scavenged, hunted, or filtered food from the seafloor. Their exoskeleton, made of calcite, was molted as they grew, contributing to their abundant fossil remains. The extinction of trilobites coincided with the Permian-Triassic extinction event, the most severe in Earth's history. The classification of Trilobata as a distinct phylum is debated among paleontologists, with some considering it an order within the phylum Arthropoda.