Diagnostic Features
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Test ovate with distinct anterior sulcus; posterior face truncate.
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Apical disc hemiethmolytic or ethmolytic with four gonopores; wider than long with anterior and posterior gonopores on either side close together; central.
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Ambulacrum III sunken from apex to peristome (deepest aborally). Pore-pairs differentiated with prominent interporal ridge, presumably associated with funnel-building tube-feet.
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Paired ambulacra petaloid; petals sunken and bowed; closed distally. Posterior petals generally about half to two-thirds length of anterior petals.
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Peristome pentagonal and tilted slightly towards anterior.
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Labral plate longer than wide, extending to third ambulacral plate. Sternal plates large, symmetrical and forming most of oral surface. Episternal plates offset.
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Periproct small, situated towards top of posterior truncate face.
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Enlarged subanal pore-pairs present.
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Peripetalous fasciole present; indented by one plate behind anterior petals. No other fascioles.
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Distribution
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Upper Cretaceous (Upper Cenomanian to Maastrichtian), Europe, former SSU, Africa, North and South America.
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Name gender |
masculine |
Type |
Hemiaster fourneli Agassiz & Desor 1847, p. 16, by original designation.
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Species Included |
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M. fourneli Deshayes, in Agassiz & Desor, 1847; Turonian to Maastrichtian, Brazil, North and West Africa.
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M. africanus (Coquand, 1862); Turonian, Algeria and Brazil.
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M. longus Cotteau & Gauthier, 1895; Senonian, Iran.
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M. mutabilis (Lambert, 1933); Turonian, Madacascar and India
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M. obliquetruncatus Peron & Gauthier, 1880; Turonian, Algeria.
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M. texanus (Roemer, 1849); Santonian-Campanian, North and central America.
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M. batnensis (Coquand, 1862); Cenomanian-Turonian, Brazil, North Africa, Texas.
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M. scutigera (Forbes, 1850); Cenomanian, Portugal.
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M. victoris (Lambert, 1932); Campanian-Maastrichtian, Algeria, Oman, Turkey.
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M. cubicus Desor, in Agassiz & Desor; Cenomanian, Middle East.
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M. arnonensis Neumann, 1999; Santonian, Jordan.
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many other nominal species of questionable validity have been established (see Neraudeau 1994 for comprehensive list and Smith & Bengtson 1991 for discussion of genus).
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Classification and/or Status |
Spatangoida, Hemiasterina, Hemiasteridae.
Paraphyletic?
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Remarks |
Differs from Hemiaster in having an ethmolytic (or hemiethmolytic) apical disc. It also has much longer and better developed petals than Hemiaster. Closest to Jordaniaster but differs in having a shorter labrum, more symmetrical sternal plates and an ethmolytic rather than ethmophract apical disc.
Smith, A. B. & Bengtson, P. 1991. Cretaceous echinoids from north-eastern Brazil. Fossils and Strata 31, 1-88.
Neraudeau, D. 1994. Hemiasterid echinoids (Echinodermata: Spatangoida) from the Cretaceous Tethys to the present-day Mediterranean. Palaeogeography, Palaeoclimatology, Palaeoecology 110, 319-344.
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