Mamers, near Saint Rémy du Val (Jurassic of France)

Also known as Saint Rémy du Plain, Le Mans

Where: Pays de la Loire, France (48.3° N, 0.4° E: paleocoordinates 37.0° N, 11.3° E)

• coordinate based on nearby landmark

• small collection-level geographic resolution

When: Ludwigia murchisonae ammonoid zone, Tessé Sandstones Formation, Middle Aalenian (175.6 - 171.6 Ma)

• In the description of GUILLIER (1886), the base of the Bajocian is defined as the Lower Oolithe stage with Terebratula perovalis, the level where the plesiosaur specimen was unearthed. GUILLIER (1886) gives a precise description of the fossils discovered in this horizon, quoting especially Ammonites murchisonae (today Ludwigia murchisonae). This species corresponds to the Murchisonae Zone, characteristic of the middle Aalenian (GRADSTEIN 2004). A study of the matrix samples still attached to the plesiosaur specimen confirms this dating. The matrix consists of red sandstone with calcareous cement. This sandstone corresponds to the JUIGNET et al. (1984) description of the Aalenian Tessé Sandstone. We can thus safely conclude that the plesiosaur discovery of Saint-Rémy du Val comes from the Aalenian, and more especially from the middle Aalenian.

Environment/lithology: peritidal; fine-grained sandstone and calcareous sandstone

• The local palaeogeographic conditions during the Aalenian indicate a shallow marine environment. The Saint-Rémy du Val locality is located on the southern margin of the emerged Palaeozoic Perseigne Massif, not affected by the Jurassic transgressions. JUIGNET et al. (1984) indicate, according to the various Aalenian local sequences, supratidal to infra-littoral conditions subject to the action of strong currents.
• The Aalenian stage is represented locally by the Tessé sands and gravels. This formation was described from the Tessé quarries, commune of Villaines la Carelle, located 5 km from Saint-Rémy du Val (JUIGNET et al. 1984). This formation is 11 to 12 meters thick and presents three main sequences, each overlapped by a hardground surface with oyster encrustations. These sequences are usually made of alternating fine sands and calcareous sandstones.

Size class: macrofossils

Collected in the 1800s

Collection methods: quarrying, mechanical,

• The specimen was first kept in the Museum of Le Mans and has followed the successive moves of the collections. Initially presented in the ‘Musée de la Préfecture’, it was then displayed in the ‘Musée de Tessé’ from 1927 until the beginning of the 1950’s, and finally placed in storage until 1995, date of the opening of the ‘Musée Vert, Musée d’Histoire Naturelle’ of Le Mans. The specimen is now permanently displayed to the public under the collection number MHNLM.2005.16.

Primary reference: P. Vincent, N. Bardet, and N. Morel. 2007. An elasmosaurid plesiosaur from the Aalenian (Middle Jurassic) of Western France. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 243(3):363-370 [R. Benson/R. Benson/R. Benson]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 140648: authorized by Roger Benson, entered by Roger Benson on 14.03.2013

Creative Commons license: CC BY (attribution)

Taxonomic list

Cephalopoda
 Ammonitida - Graphoceratidae
Ludwigia murchisonae Sowerby 1825 ammonite
Reptilia
 Sauropterygia - Elasmosauridae
Elasmosauridae indet. Cope 1869 elasmosaur
MHNLM.2005.16, the vertebral column includes 23 cervicals, 4 pectorals, 17 dorsals, 3 sacrals, and 11 caudals. Most of the cervicals and some dorsals have been found in articulation (see Fig. 1). Both humeri have been found associated with the vertebrae. Only their proximal extremities are preserved. It can be assumed with safety that the material belongs to the same specimen