Crateroseris
Tomes, 1883, p. 560
Type Species
Crateroseris fungiformis Tomes, 1883, p. 560, pl. 22 fig. 11-14; Monotypy
Type Specimen: Lectotype; NHMUK R 7840; Verified; Dry Preserved
Type Locality: Oxfordian (Upper Jurassic) of Steeple Ashton (Great Britain)
The lectotype R 7840 is a dry sectioned specimen with 3 thin sections it was abusively designated as holotype (ICZN art. 74) by Negus and Beauvais (1979). Specimen R 7841 is a paralectotype. Other topotypical samples were collected and published in Negus and Beauvais (1979).
Classification
Description
Massive thamnasterioid corallum of plocoid appearance . Lower surface covered by subequal costae and some weak annular traces of "epitheca". Corallite distinct by their relief of craters or by the straightness of radial elements. In the tissue around the corallites radial elements are more sinuous. Intercalicular increase. Radial elements are compact or subcompact, anastomosed, generally confluent. Distal edge ornamented of regular robust well separated teeth (heads of trabecules). Inner edge attenuated with oblique small teeth, lateral faces ornamented with pennules laterally united in menianes but more generally producing a festoon pattern (seen from above). No pali. Hexameral symmetry difficult to see if present, bilateral symmetry marked in young corallites by the anastomoses of septa. Endotheca made of vesicular dissepiments. Columella styliform, papillose or absent (the lectotype and the paralectotype differ in this respect), synapticulae present, wall absent.
Remarks
Radial elements are neither septa s.s. nor costosepta nor biseptal sheets. They are formed of two costosepta united between corallites. It is like a biseptal sheet but with two fan systems. One nominal species known.
Distribution
- Western Europe; Late Jurassic
This page has been in preparation since 07-May-2009 10:50
This version was contributed by Bernard Lathuilière on 04-Feb-2010 16:30.
Page authors are: Bernard Lathuilière. Please contact the editor if you would like to contribute to the diagnosis of this taxon.
The editor is: Bernard Lathuilière
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