Search results for "Lower ordovician"
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ABNORMALITIES IN THE LOWER ORDOVICIAN CORNUTE PHYLLOCYSTIS THORAL, 1935 (ECHINODERMATA: STYLOPHORA) FROM MONTAGNE NOIRE (SOUTHERN FRANCE): IMPLICATIO…
2007
9 pages; International audience; Two specimens of the cornute Phyllocystis crassimarginata Thoral, 1935 from the Lower Ordovician of Southern Montagne Noire (Languedoc, France) showing abnormal numbers of marginal plates are described. The first one (UM 310) is characterized by the insertion of one extra plate between the fourth right marginal and the zygal plate Z. Comparison with a new, undescribed Tremadoc boot-shaped cornute suggests that 1) the extra plate of UM 310 is equivalent to M4, and 2) the three right marginals located between M1 and Z in ‘‘normal'' specimens of Phyllocystis can be identified as M2, Mc, and M3. Plate configurations of the right thecal margin are thus identical …
First report of the mitrate Peltocystis cornuta Thoral (Echinodermata, Stylophora) in the Lower Ordovician of central Anti-Atlas (Morocco)
2007
The mitrate Peltocystis cornuta is one the best known and most abundant stylophoran echinoderms in the Lower Ordovician (upper Tremadoc - lower Arenig) of Montagne Noire (southern France). It is here documented outside this region for the first time, in coeval deposits of central Anti-Atlas (Morocco). This report confirms the strong faunal affinities between Montagne Noire and Moroccan assemblages in the Ordovician. Twenty-eight individuals of P. cornuta are described from two distinct localities of the Zagora region. Their overall morphology is very comparable to that of Montagne Noire specimens. However, the Moroccan Peltocystis differ from the French ones in their smaller mean size, and …
New specimens of Lingulocystis Thoral, 1935 (Eocrinoidea, Blastozoa) from the Arenig (Lower Ordovician) of Montagne noire (southern France): Intraspe…
2007
16 pages; The genus Lingulocystis Thoral, 1935 is a preponderant component of the echinoderm fauna of the Lower Ordovician of Montagne noire (France), as suggested by its abundant remains. Its morphology is characterized by a flattened theca, composed of a frame enclosing numerous small polygonal central plates. The new specimens have been determined partly as Lingulocystis elongata Thoral, 1935 and partly as Lingulocystis aff. deani Ubaghs, 1994. This study is the first report of Lingulocystis in the Foulon Formation. New stratigraphic ranges have been defined for both species: L. elongata from the early Tremadoc (Saint- Chinian Formation) to the middle Arenig (lower part of the Landeyran …