Holasteroida

Holasteroida Temporal range: Early Cretaceous–recent PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Echinodermata
Class:	Echinoidea
Subclass:	Euechinoidea
Infraclass:	Irregularia
Superorder:	Atelostomata
Order:	Holasteroida Durham & Melville, 1957

Holasteroida is an order of irregular sea urchins.

Characteristics[]

Ceratophysa ceratopyga by A. Agassiz (1881)

These irregular sea urchins are characterized by a particularly marked bilateral symmetry, including for the apical system, which is highly elongated. In some contemporary abyssal groups such as Pourtalesiidae, some species are even bottle-shaped. The mouth (peristome) does not contain an Aristotle's lantern. The anus (periproct) has migrated towards the periphery of the test. The plastron is never amphisternous.^[1]

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  Fossile of Hemipneustes pyrenaicus (Hemipneustidae, Maastrichtian)

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  (Pourtalesiidae)

This order seems to have appeared at the lower Cretaceous.^[1]

List of families[]

According to World Register of Marine Species :

• Family Hemipneustidae (Lambert, 1917) †
  • genus Hemipneustes L. Agassiz, 1835 †
  • genus Jeffery, 1997 †
  • genus Gauthier, 1889 †
  • genus Smith & Wright, 2003 †
  • genus Toxopatagus Pomel, 1883 †
• Sub-order (Lovén, 1883)
  • Infra-order †
    • Family Lambert, 1917 †
    • Family Lambert, 1917f †
  • Family Wright, 1857 †
  • Family Holasteridae Pictet, 1857 †
    • Genus Saucède, Dudicourt & Courville, 2012 †
  • Infra-order
    • Family Calymnidae Mortensen, 1907
    • Family Carnarechinidae Mironov, 1993
    • Family Corystusidae Foster & Philip, 1978
    • Family Plexechinidae Mooi & David, 1996
    • Family Pourtalesiidae A. Agassiz, 1881
    • Family Urechinidae Duncan, 1889
• Family (Smith & Jeffery, 2000) †
  • genus Solovjev, 1989 †
  • genus Foster & Philip, 1978 †
  • genus Pomel, 1883 †
  • genus Pomel, 1883 †
• Family (Lambert, 1922) †
  • genus Lambert, 1922 †

References[]

• Holasteroida at the Natural History Museum
• Kroh A, Mooi R (eds.). "Holasteroida". World Echinoidea Database. World Register of Marine Species.

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