Starfish first appeared in the fossil record in the Cambrian. The first known asterozoans were the Somasteroidea, which exhibit characteristics of both groups. Starfish are infrequently found as fossils, possibly because their hard skeletal components separate as the animal decays. Despite this, there are a few places where accumulations of complete skeletal structures occur, fossilized in place in Lagerstätten — so-called "starfish beds". By the late Paleozoic, the crinoids and blastoids were the predominant echinoderms, and some limestones from this period are made almost entirely from fragments from these groups. In the two major extinction events that occurred during the late
Phylum for Chromista and Protozoa by the Catalogue of Life, adapted from the system used by the International Society of Protistologists. The Catalogue of Life includes Rhodophyta and Glaucophyta in kingdom Plantae, but other systems consider these phyla part of Protista. Currently there are 29 phyla accepted by List of Prokaryotic names with Standing in Nomenclature (LPSN) Currently there are 5 phyla accepted by List of Prokaryotic names with Standing in Nomenclature (LPSN). Phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below Kingdom and above Class. Traditionally, in botany the term division has