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The Eocrinoidea were an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, brachiole-bearing echinoderms, and were the most common echinoderms during the Cambrian. The earliest genera had a short holdfast and irregularly structured plates. Later forms had a ...
Micraster is an extinct genus of echinoids from the Late Cretaceous to the early Eocene.Its remains have been found in Africa, Antarctica, Europe, and North America.Micraster was an infaunal echinoid living in a burrow below the sediment surface.
"Blastoidea", from Ernst Haeckel's Art Forms of Nature, 1904. Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. [1] They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississippian subperiod of the Carboniferous period.
An echinoderm (/ ɪ ˈ k aɪ n ə ˌ d ɜːr m, ˈ ɛ k ə-/) [2] is any animal of the phylum Echinodermata (/ ɪ ˌ k aɪ n oʊ ˈ d ɜːr m ə t ə /), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". [3]
Edrioasteroidea is an extinct class of echinoderms.The living animal would have resembled a pentamerously symmetrical disc or cushion. They were obligate encrusters and attached themselves to inorganic or biologic hard substrates (frequently hardgrounds or brachiopods). [1]
A brittle star, Ophionereis reticulata A sea cucumber from Malaysia Starfish exhibit a wide range of colours. This List of echinoderm orders concerns the various classes and orders into which taxonomists categorize the roughly 7000 extant species [1] as well as the extinct species of the exclusively marine phylum Echinodermata.
This list excludes purely vernacular terms. It includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (nomina dubia), or were not formally published (nomina nuda), as well as junior synonyms of more established names, and genera that are no longer considered echinoderms. The list includes thousands of ...
However, it is now generally accepted that homalozoans were echinoderms because their calcite skeleton was composed of the typical stereom crystalline structure. [ 6 ] They include the unusual stylophorans ( mitrates and cornutes ), Homoiostelea ( solutes ), the Homostelea (cinctans), and the Ctenocystoidea (ctenoid-bearing homalozoans). [ 7 ]