Simosaurus

Abstract: Bobosaurus forojuliensis , gen. et sp. nov., is a large sauropterygian from the Alpine Late Triassic (Early Carnian, northeastern Italy). The holotype is 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 is characterized by a mosaic of "nothosaurian" and "plesiosaurian" features. It exhibits characters that were previously considered autapomorphies of different sauropterygian taxa. Dorsal neural spines are very high as in Nothosaurus mirabilis , and each dorsal rib has a distinct uncinate process, a diagnostic feature of the placodont Paraplacodus . 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 obturator foramen and an articulation with the ilium, and is associated with a stout, "hourglass-shaped" ilium that has a twisted shaft. Apomorphic characters include: cervical centra higher than wide and "pear-shaped" in anteroposterior view, a peculiar zygapophyseal articulation of pectoral to "caudal" vertebrae like that found in the dorsal vertebrae of Simosaurus , but with 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. It is 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.

Abstract: The nothosauroid sauropterygian Simosaurus is reported for the first time both from Italy and from the early Carnian (earliest Late Triassic). Diagnostic dorsal neural arches and clavicles as well dorsal ribs have been collected in the Rio dal Lago Formation near Dogna (Friuli). Purported Simosaurus remains from the Ladinian of Austria cannot be attributed to this genus with certainty and the presence of additional articular structures in the dorsal neural arch ("infraprezygapophyses" and infrapostzygapophyses) cannot distinguish Simosaurus from Bobosaurus if the craniocaudal polarity or other vertebral features are unknown.

Abstract: Simosaurus is a Triassic eosauropterygian genus known from cranial and postcranial elements, found in the Middle and Upper Triassic strata of Europe and the Middle East. Simosaurus gaillardoti is currently recognised as the only valid species of the genus, identified in Ladinian strata of an area that includes northeastern France (Lorraine) and southwestern Germany (Baden-Württemberg). The remains from this area include more than 20 skulls. Although some of them were described in detail and figured by several authors since the discovery of S. gaillardoti, many others remained unpublished. Here we study and figure 25 skulls from this taxon, reviewing the previously known specimens, and presenting and analyzing numerous unpublished skulls. This significant sample of skulls from a single taxon of a European Triassic eosauropterygian allows us to recognise intraspecific variability in characters previously identified as non-variable in this species, including some that are often included in phylogenetic analyses of these reptiles. Therefore, we markedly increase our knowledge of the cranial skeleton in this taxon.

Abstract: The genus Simosaurus has been found in the rich sauropterygian fauna of the Muschelkalk (Middle Triassic) of the Makhtesh Ramon (Wadi Raman), and is known from European sites of the same age. Anatomical details of the single specimen, a skull fragment, are discussed. However, the specimen is too incomplete to merit a specific denomination. The vertebrates of the Makhtesh Ramon Muschelkalk are briefly reviewed.