Le Naturaliste Vendéen, Numéro 3 (2003)
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Un busard cendré, Circus pygargus, consommateur d'oeufs de Sternes pierregarins, Sterna hirundo
(2003)
On the lagoon of Bouin, in the Baie of Bourgneuf in Vendée (France), a Montagu’s harrier has been observed on several occasions eating the eggs of Common Tern. This type of predation does not appear to be very frequent with this species of raptor.
One of the remaining French otter populations lives on Noirmoutier island where the marine environment offers food resources. A study of the otters' diets will prove if these resources are used or not.
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.
In 1869 Tacite Letourneux described a new species of gasteropod, Valvata bourguignati, in a spring in south-east Vendée. The name of this new species was later considered to be synonymous with Neohoratia globulina. Recent samplings in the Locus typicus have permitted the revision of this taxon, now named Islamia moquiniana.
A micro-crustacean has recently been discovered in Vendée. It is an Ostracod living in temporary bodies of slightly brackish or fresh water. From the Cyprididae family, Cypris bispinosa is a crustacean whose presence in France is only known from eight countess. It is however one of our largest ostracods, and the lateral spine fixed on each side of its carapace make the species easily recognisable with a lens.
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.
It has been forty years since the Jurassic site of Veillon in Talmont-Saint-Hilaire (Vendée, France), where footprints of vertebrates were found, was plundered. This outstanding site belonging to Vendée's geological patrimony needs to be preserved and developed. Some footprints from Veillon are displayed in the collections of about thirty public institutions and six museums.
Using the fossil dinosaur footprints of the lower Lias of Le Veillon at Talmont-Saint-Hilaire, (Vendée) as a starting point, the reconstitution by pupils of a unique fossil-bearing site is under consideration. The paleobiology and paleoecology of reptiles in this geological site are dealt with.
Palichnites et muséologie
(2003)
After they had intrigued the inquiring or observant mind for decades, it was realised that certain "natural curiosities" were tracks of extinct creatures, related to gigantic birds or other antediluvian animals. At the beginning of the XIXth century a new science, ichnology, came into being and developed, thanks to the collection, preservation and study of fossil prints. The increasing quantity of evidence thus unearthed reveals the diversity of vertebrate faunas which have trod the earth’s surface and left behind valuable information about their characteristics and behaviour. Like other institutions labouring on behalf of conservation, knowledge of nature and the preservation of our natural heritage, the Nantes Natural History Museum has, for nearly two centuries, collected, conserved, displayed and brought to the attention of the public those valuable pieces of evidence, fossil footprints. Displays of fossil prints are regularly presented during different exhibitions. Examples of them permit one to follow the evolution of our knowledge of these prints and illustrate how the information yielded by these prints has been transmitted.
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 Liassic Talmont-Saint-Hilaire (Vendée, France) outcrop has been studied here according to the abundance of fossil plants of the Cheirolepidiaceous family (Gymnosperms, Coniferales). A new species of Brachyphyllum has been studied in light microscopy, even in scanning electron microscopy and transmission electron microscopy. It is, at that time, one of the most complete study realized on a fossil taxon. Epidermal cells, subsidiary cells and guard cells have been described on both adaxial and abaxial surfaces, in transversal and longitudinal sections. Cuticle ultrastructural variations have been observed between epidermal and stomatal cells. To conclude, we propose a discussion about the cuticle structure variations related to environmental conditions and the functional morphology of the different cells.
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.
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).
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.
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.
The Veillon ichnofauna, early Liassic in age, includes various Reptile taxa: quadruped Pseudosuchian, Coelurosaurians, Theropods, primitive Iguanodon – like Ornithopods and some unspecified forms. This ichnofauna is very comparable to the early Liassic footprint assemblage of the Connecticut.
Clastic deposits related to alluvial and estuarine environments sedimented during the early Liassic in the Veillon area (south of Talmont-Saint-Hilaire, Vendée, France). A reptile fauna including various taxa, just known by innumerable footprints, lived in that environment, in rather hot and dry climatic conditions.
In the Talmondais (Vendée) the Hettangian sedimentation locally begins with fluviatil clastic deposits prior to the deposition of shallow marine carbonates. These clastics, including the footprint-bearing beds of Le Veillon (south of Talmont- Saint-Hilaire) are subject to important and frequent variations in thickness. Drilling and geophysic data indicate a tectonic control of these variations. A fault-block pattern is proposed. At a small scale, it gives an illustration of the extensional tectonic processes related to the evolution of the Biscay rift during the early Liassic.
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.
On the intertidal zone of Le Veillon at Talmond-Saint-Hilaire (Vendée, France), in 1963 Gilbert Bessonnat discovered traces of vertebrate footprints in a Hettangian formation. On March 28th & 29th, at this site a study session was held on the theme: "sites with vertebrate footprints on the Triassic-Jurassic limit". Palæontologists, palæobotanists, sedimentologists, hydrologists, scientific historians and naturalists compared their results and projected further research. This exceptional Vendée heritage site is to be protected and developed.