Alloiteau, 1957, p.111
Montlivaultia excelsa Fromentel 1861: p. 116; Original Designation
Type Specimen: Lectotype; MNHN M03588; Verified; Dry Preserved
Type Locality: "Betaincourt" (very probably Bettaincourt sur Rognon, Haute Marne France, Middle Oxfordian)
Solitary, proximally trochoid then subcylindric. Weakly infundibuliform calicular platform. Elliptical tranverse section. Radial elements are compact costosepta straight or slightly curved. Major septa anastomosing in the central zone, other seem to be free. Lateral faces show granules arranged in carinae perpendicular to the distal edge. Septal microstructure unknown. Bilateral symmetry marked by the curvature of septa, the elongation of the axial zone as well as the elliptical section. Inner edge of major septa anastomosed to the sublamellar columella. Abundant endotheca made of dissepiments arranged parallel to the distal edge of septa. Smooth parathecal wall. No synapticule, no pali.
The lectotype comes from an outcrop (Bettaincourt) where most of the fossils are rolled in a high energy environment. The absence of epitheca, the appearance of the "columella" and the relief of the calice can be related to this taphonomic history. The figure of a radial element in lateral view by Alloiteau 1957 cannot be recognised on the lectotype. An interpretation of a rolled Montlivaltia cannot be discarded. Placed by Alloiteau among Smilotrochidae. 4 Jurassic nominal species but very few fossils.
- Western Europe; Late Jurassic
This page has been in preparation since 07-May-2009 07:29
This version was contributed by Bernard Lathuilière on 21-Oct-2009 07:27.
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