Le Naturaliste Vendéen, Numéro 3 (2003)
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- Fischotter (1)
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Discovery of a single example of Mirror Orchid (Ophrys speculum) in the coastal forest of Longeville-sur-Mer, in southern Vendée. This orchid, hitherto unknown in Vendée, is very rare in France.
The Ichnospace is a specific exhibition dedicated to traces and tracks left by recent and fossil animals on ground. The Ichnospace is located at Luzech, a little town with a long historic past, near Cahors (about 17 km W) in the valley of the river Lot. Every living being leaves traces of its activities (habitat, locomotion, diet, etc.) in its environment. These traces are the signing of the individual and they may be preserved and fossilised in geological time. They provide information about biodiversity, the habits of individuals and their distribution in time and space. In the Causses of Quercy area very near of Luzech and well known by palaeontologists and geologists, many dinosaur and pterosaur tracks have been discovered. Some of them are exposed with various fossil invertebrates, turtles, crocodiles and so on, from upper Jurassic when the sea Tethys ran along shores of the large Central island. Movie and an audio-visual show complete the exhibited specimens with French and English comments.
Hettangian stratotype shows an example of preservation and valorisation of a scientifical historical place. Earth Story is understood thanks to geological heritage; this heritage is very vulnerable. Judicial framework and mentality evolution allow us to make a conservation of particularly interesting places.
The region of Talmont-Saint-Hilaire (Vendée, France), located at the contact between the Armorican Massif, the Aquitanian Basin and the Atlantic Ocean, has been studied by many geologists and geographers, over the last three centuries. In the years 1780, silver was mined from the sulphide-bearing ore that occurs at the base of the Jurassic limestones. The stratigraphy of the latter sediments, as well as their relationship with the hercynian basement, was investigated during the 19th and 20th centuries, mainly by Rivière, the author of the first geological map of the area (1838), Cossmann, Vasseur, Péneau, Ters and Butel. As for Gabilly, he considered the anse Saint-Nicolas as a para-stratotype of the Toarcian. A few Authors, mainly Bocquier and Ters, also studied the evolution of the Atlantic coast during Quaternary. They evidenced remnants of several surfaces fashioned by marine abrasion, the age of which was constrained by archaeological studies. In 1963, Gilbert Bessonnat discovered dinosaur footprints, which, however, had already been observed by Bocquier in the years 1930. Montenat and Lapparent studied the occurrence, which proved to be one of the richest in Europe.
In the inter/supratidal algal mats, the early diagenesis products a progressive induration. It is enough to preserve all the deformations affecting the mats, including footprints of vertebrates, tracks and burrows of small invertebrates, and physical actions (desiccation cracks).
Analyse d'un exemple de fossilisation d'une trace de pas de Dinosaure (Lias inférieur des Causses)
(2003)
A calcareous block made of algo-laminated (stromatolitic) material exhibits at its upper surface a foot print of a Dinosaurian. A vertical section (sawing) and a thin section allow to make detailed observations. The early diagenesis permits the preservation of the deformations caused by the foot print.
Tandonia rustica (Millet 1843) (Mollusca : Gastropoda), nouvelle espèce de limace pour la Vendée
(2003)
The slug Tandonia rustica has recently been discovered in the forest of Mervent, in Vendée. After a brief description of the site where the gastropod was found, the author describes the biology, ethology and distribution in France of this species.
Numerous footprints areas has been found, since 1962, in Permian, Triassic and Hettango-Sinemurian. All show precised oriented trackways. So that they were undestood like walking ways but their precise meaning is still enigmatic.
Footprints are numerous in France where they found from Carboniferous to Quaternary levels. Those of Middle Triassic (Anisian-Ladinian) are especialy interesting because they are tridactyl footprints made probably by first dinosaurs. First skelettons are known from Upper Ladinian / lower Carnian.
Comparaison des ichnopopulations des Grands Causses (Sud de la France) et du Veillon (Vendée)
(2003)
From descriptive statistic method concerning length (L), width (W) and L/W, it is suggested that Grallator variabilis samples from Vendée (Le Veillon) and Grands Causses belong to the same ichnospecies. Also, by this way, G. maximus of Hettangian of Vendée could be synonym of G. minusculus from USA Hettangian.