Fabio M.Dalla Vecchia

Academic paper

Rivista Italiana di Paleontologia e Stratigrafia

112

2

207-225

Bobosaurus forojuliensis, gen. et sp. nov., ls a large sauropterygian from the Alpine Late Triassic (Early Carnian, north-eastern Italy). The holotype ls a moderately disarticulated skeleton consisting of the tip of the rostrum, part of the neck (including the atlas�axis complex), the trunk, most of the tail, parts of the limbs, and the pelvic girdle. The new taxon ls characterized by a mosaic of "nothosaurian" and �plesiosaurian" features. It exhibits characters that were previously considered autopomorphies of different sauropterygian taxa. Dorsal neural spines are very high as in Nothsaurus mirabilis, and each dorsal rib has a distinct unciate process, a diagnostic feature of the placodont Paraplodocus. The atlas�axis complex has the plesiosaurian pattern but is peculiar in several details. The neural spines of the anterior cervicals have an arched anterior margin. The spade�shaped pubis lacks an obdurator foramen and an articulation with the ilium, and is associated with a stout, "hourglass�shaped" ilium that has a twisted shalt. Apomorphic characters include; cervical centra higher than wide and "pear�shaped" in anterior view, a peculiar zygapophyseal articulation of pectoral to �caudal� vertebrae like that found in the dorsal vertebrae of Simosaurus, but wlth a reversed anteroposterior polarity , high neural spines on all vertebrae, neural spine of "sacral" to mid-caudal vertebrae with a bottle�shaped profile in lateral view, peculiar mid-posterior cervical ribs, lightened skeleton, and a comparatively large humerus. The new taxon was a specialized surface swimmer with a stiffened trunk and large forelimbs. It represents one of very few Late Triassic eusauropterygian taxa. lt ls probably a pistosaurid, or alternatively, could represent a different clade closer to Plesiosauria, occurring in the gap between the late Anisian pistosaurids and the earliest Rhaetian plesiosaurs.

English