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Supporters of pentaradiality as an initial condition of the phylum note that radial forms are the first uncontested echinoderms to appear in the fossil record. They also define homologies of echinoderm anatomy based on a division of the skeleton into two parts: those that are or are not associated with the water vascular system.
Pseudodiadematidae are members of the phylum Echinodermata. [1] Their fossil remains date to the Cretaceous period (144 - 66.4 MYA). Its child geniuses are Acanthechinopsis, Acrocidaris, Acrotiaris and Aplodiadema. The distribution of fossils in the Cretaceous are in Algeria, Brazil, Egypt, France, Hungary, Jordan, Madagascar, Morocco, Nigeria ...
Echinoderms – 72% of all documented species of Echinodermata are fossils and extinct. [7] Subphylum Crinozoa (sessile echinoderms) – 91% of all documented species of Crinozoa are now extinct Class Crinoidea (crinoids / sea lilies) – See Crinozoa above; Subphylum Blastozoa [†] (extinct blastoids) Class Diploporita; Class Rhombifera
Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. [5] They live in both shallow water [6] and in depths of over 9,000 metres (30,000 ft). [7] Adult crinoids are characterised by having the mouth located on the upper surface.
Crinozoa is a subphylum of mostly sessile echinoderms, of which the crinoids, or sea lilies and feather stars, are the only extant members. [1] [2] Crinozoans have an extremely extensive fossil history. [citation needed]
"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.
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 of prehistoric echinoderms is an attempt to create a comprehensive listing of all genera that have ever been included in the Echinoderms that have been preserved as fossils. This list excludes purely vernacular terms.