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Viminohelia

Geyer, 1954, p. 153

Type Species

Viminohelia seminuda Geyer, 1954, p. 154, pl. 16 fig. 8; Original Designation

Type Specimen: Holotype; SMNS 19277; Verified; Dry Preserved

Type Locality: Upper Malm (Upper Jurassic), Sinabronn (Germany)

The holotype is a silicified sample. We used some recent samples (n°67657 from Stuttgart Museum) in a better state of preservation to describe and illustrate this genus.

Classification

Description

Foliaceous, unifacial corallum made of anastomosed branches on which a stretched thamnasterioid structure is developed by lateral increase of the colony. It could be described also as meandroid with voids and anastomoses in place of collines. No epitheca, but thin costae with a low relief. Distinct centers. Radial elements are compact anastomosed biseptal sheets, subequal, sinuous to geniculate. Distal edge occasionally moniliform but not always ornamented, inner edge attenuated and anastomosed, lateral faces clearly pennular with very continuous menianae. Pennular rims No palis. Microstructure trabecular (as suggested by occasional moniliform pattern of the distal edge). Hexameral symmetry not deciphered, bilateral symmetry obvious with elongation of biseptal sheets in the length of branches. Endotheca not observed. Axial zone generally marked with a distinct fossa in depth of which a variable columellar structure occurs (from styliform to weak parietal with very small trabecular projections of inner edges), synapticulae not observed. Wall absent between corallites within a branch (or a "valley") but a wall-like structure of unknown nature is located on the anastomoses between branches.

Remarks

One nominal species, one citation known, but the species is rather common in some particular outcrops of the Nattheimer Schichten (oral com. G. Schweigert)

Distribution

  • Western Europe; Late Jurassic

This page has been in preparation since 20-Aug-2009 09:54

This version was contributed by Bernard Lathuilière on 27-Oct-2012 11:43.

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


Holotype of Viminohelia seminuda type species of the genus
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Specimen of Viminohelia seminuda type species of the genus
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Specimen of Viminohelia seminuda type species of the genus
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Specimen of Viminohelia seminuda type species of the genus
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