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[dinosaur] Kayentapus ubacensis, new theropod track species from Middle Jurassic of France

Ben Creisler

A new paper:


Kayentapus ubacensis nov. isp.

Georges Gand, Emmanuel Fara, Christophe Durlet, Jean-David Moreau, GwÃnaÃl Caravaca, Louis Baret, Daniel AndrÃ, Raymond Lefillatre, Alain Passet, Michel WiÃnin & Jean-Paul GÃly (2018)
Les pistes dâarchosauriens : Kayentapus ubacensis nov. isp. (thÃropodes) et crocodylomorphes du Bathonien des Grands-Causses (France). ConsÃquences palÃo-biologiques, environnementales et gÃographiques.
Archosaurian trackways: Kayentapus ubacensis nov. isp. (theropods) and crocodylomorphs from the Bathonian of the Grands-Causses (France). Palaeo-biological, environmental and geographical implication.
Annales de PalÃontologie (advance online publication)
doi: https://doi.org/10.1016/j.annpal.2018.06.002Â

Two tracksites yielding tridactyl footprints II-IV of theropods as well as supposedly sauropod tracks from the Causses Basin, briefly described in 2006 are reinvestigated. They are the Capelan tracksite (Meyrueis, LozÃre) and the GarÃne tracksite (La Roque-Sainte-Marguerite, Aveyron), both Bathonian in age. In 2012, one of them (Le Capelan) was excavated and enlarged, allowing the discovery of numerous new tracks. In the Capelan tracksite, 102 concave epireliefs, 11 to 36 cm long, represent at least 21 trackways; the longest being visible along 37 meters. Footprints are almost as long as wide and show a large divarication angle II-IV (up to 70Â). The largest of them (more than 24 cm long) were statistically compared with different Middle and Upper Jurassic ichnotaxa for which a synthesis is proposed. Tracks from the Causses Basin as well as those from the Capelan and the GarÃne tracksites can be ascribed to the ichnogenus Kayentapus. We propose a new ichnospecies K. ubacensis nov. isp. Whose trackmakers were tetanurian theropods, probably megalosaurids. At the Capelan, some marks are tentatively interpreted as swim tracks of crocodylomorphs. The supposedly sauropod tracks are here reinterpreted and considered as erosion cups and as concavities indicating the location of tree trunks. The sedimentological analysis indicates a paralic environment including lagoons and freshwater to brackish bays. They were separated from dysoxic lagoons by calcarenitic coastal barrier spits, and by tidal flats where microbial mats contributed to the good preservation of trackways. Despite the presence of 'mangroves', the main track-bearing surface from the Capelan was quite open and visited by megalosaurid dinosaurs of various sizes, moving in all directions but preferably to the North. The regional palaeogeography of the early-middle Bathonian is in accordance with a coastal area with low relief, bordering the 'Seuil CÃvenol', which was probably emerged.