Megalosauripus transjuranicus ichnosp. nov. A new Late Jurassic theropod ichnotaxon from NW Switzerland and implications for tridactyl dinosaur ichnology and ichnotaxomy

摘要: A new ichnospecies of a large theropod dinosaur, Megalosauripus transjuranicus, is described from the Reuchenette Formation (Early-Late Kimmeridgian, Late Jurassic) NW Switzerland. It based on very well-preserved and morphologically-distinct tracks (impressions) several trackways, including different preservational types tracksites horizons. All trackways were excavated along federal Highway A16 near Courtedoux (Canton Jura) systematically documented in field orthophotos laserscans. The best-preserved recovered additional casted. transjuranicus characterized by tridactyl with clear claw digital pad impressions, notably an exceptionally round first phalangeal fourth digit (PIV1) that connected to IV forms heel area. Due this combination features, M. clearly (and not ornithopod) origin. compared other similar ichnotaxa unassigned Early Jurassic Cretaceous. ichnogenera assigned theropods such as Eubrontes-Grallator Triassic or Megalosauripus-Megalosauropus-Bueckeburgichnus Therangospodus second morphotype (called Morphotype II) being subsymmetric, longer than wide (sometimes almost long), blunt toe impressions no evidence for discrete marks. Some II are found M.? cf. indicating some intra-trackway variants morphological continuum transjuranicus. On hand, up 40 steps long consistently present features (notably digits) do exhibit any typical pads). Therefore, it likely these isp. These interpreted have been left ornithopod dinosaur. high frequency tidal-flat deposits Jura carbonate platform, associated single ichnoassemblages minute medium-sized tiny sauropod has important implications dinosaur community paleoenvironmental paleogeographical reconstructions. As most known occurrences tracks, coastal settings, which may reflect preference their trackmakers expanded flats where food was abundant.