Les sites à traces de pas de vertébrés du Trias à l'Hettangien : contenu et interprétation

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

Signification des aires à empreintes de pas de vertébrés des Grands Causses (Biologie et Physiologie)

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

La fossilisation des empreintes de pattes et autres traces biologiques : rôle du voile algaire et de la diagenèse précoce

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)

Gigantism among Late Jurassic limulids: New ichnological evidence from the Causses Basin (Lozère, France) and comments on body-size evolution among horseshoe crabs

International audienceAn abundant ichnological material composed of xiphosuran trackways and isolated traces was discovered in Upper Jurassic limestones from the Causses Basin (Causse Méjean, Lozère, France). The morphology of the imprints supports their identification as Kouphichnium isp. In contrast to the most frequent case, the trackways are composed of omnipresent pusher imprints sometime associated with leg traces, but with no telson mark. We argue that this pattern reflects actual surface traces rather than an incomplete set of undertracks. The size distribution of the sampled ichnites is broadly bimodal. This is best explained by sexual dimorphism, a phenomenon frequently observed in modern xiphosurans. Analysis of the trace fossils further suggests that several growth stages are recorded and that the horseshoe crabs were walking in a protected and flat environment like a lagoon. This area, certainly close to a mating ground, was occasionally affected by a continental influence. The biometric study of the tracks suggests a gigantic size for the trackmakers whose body may have reached 84 cm in length. This discovery complements the few reports on other gigantic horseshoe crabs in the Jurassic of Western Europe, thus casting doubt on the postulated increase in body size from the Palaeozoic to the Recent. Furthermore, a literature review shows that there are still major gaps in the record of limulid body-fossils and tracks. Thus, neither of these archives can be taken at face value for quantifying the body-size evolution of horseshoe crabs

Contribution à l'étude géologique des formations permo-triasiques de la partie septentrionale de Belledonne : de la vallée de l'Arly au lac de la Girotte-Savoie.

Ce travail concerne le Trias alpin de la partie septentrionale de Belledonne : affleurements de la Girotte, de la vallée de l'Arly, Crest Volland et Signal de Bisane. La sédimentation continentale est étudiée dans des zones à la tectonique très active.Pas de résum

Contribution à l'étude géologique des formations permo-triasiques de la partie septentrionale de Belledonne : de la vallée de l'Arly au lac de la Girotte-Savoie.

Ce travail concerne le Trias alpin de la partie septentrionale de Belledonne : affleurements de la Girotte, de la vallée de l'Arly, Crest Volland et Signal de Bisane. La sédimentation continentale est étudiée dans des zones à la tectonique très active.Pas de résum

Contribution à l'étude géologique des formations permo-triasiques de la partie septentrionale de Belledonne : de la vallée de l'Arly au lac de la Girotte-Savoie.

Ce travail concerne le Trias alpin de la partie septentrionale de Belledonne : affleurements de la Girotte, de la vallée de l'Arly, Crest Volland et Signal de Bisane. La sédimentation continentale est étudiée dans des zones à la tectonique très active.Pas de résum

Des géotopes à protéger, l'exemple des carrières des grès triasiques (arkoses) de la Charbonnière (Auxy, Plateau d'Autully, Saône-et-Loire).

8 pagesNational audienc