117 research outputs found
Redescription and phylogenetic relationships of Megachirella wachtleri Renesto et Posenato, 2003 (Reptilia, Diapsida)
No full textMegachirella wachtleri Renesto et Posenato, 2003, a well preserved partial reptile skeleton from the Middle Triassic of the Dolomites (N. Italy), was originally considered a lepidosauromorph, but no phylogenetic analysis was carried out. Consequently, the taxon was overlooked in later phylogenetic analyses of the Diapsida. Here, the holotype and only known specimen of M. wachtleri is redescribed, allowing an investigation of its phylogenetic relationships. Phylogenetic analyses confirm that Megachirella is a lepidosauromorph close to the crown group lepidosaurs (Squamata + Rhynchocephalia). Megachirella enhances our knowledge of the series of morphological modifications that led to the origin of the Lepidosauria, the most diverse clade of extant reptiles
A juvenile Lariosaurus (Reptilia, Sauropterygia) from the Kalkschieferzone (Uppermost Ladinian) near Viggiù (Varese, Northern Italy).
No full textThe collection of a juvenile Lariosaurus specimen in the Kalkschieferzone of Cà del Frate (Viggiù, Varese, Northern ltaly), allows the comparison with an other specimen of about the same size, collected from the same formation in the locality of Val Mara (Switzerland) and described as a new species: L. lavizzarii (Kuhn-Schnyder, 1987). The analysis of the size and proportions of both specimens testifies that the supposed difference of relative proportions between the anterior and posterior stylopodium with other known Lariosaurus specimens is due to an error in the calculation or in the plotting of the data, while allometric growth of both anterior and posterior stylopodium is confirmed. A large specimen was already collected from the same formation in the Italian locality of Cà del Frate, and it was ascribed to a separate species, L. valceresii Tintori & Renesto, 1990, on the basis of the relatively longer humerus with respect to L. balsami. This character, however, is not recognizable in the juvenile Lariosaurus specimen from the same locality. Two alternative conclusions are proposed: the small specimen belongs to the same species of the larger one, but the early growth stage obscures the main diagnostic character, or the different limb proportions in the large individual reflect sexual dimorphism rather than specific diversity
First record of Langobardisaurus (Diapsida, Protorosauria) from the Norian (Late Triassic) of Austria, and a revision of the genus
No full textLangobardisaurus Renesto 1994, is a small (body length less than 0.5 m) archosauromorph diapsid with a robust skull set on a very elongate neck (Renesto, 1994). It was originally described based on two fairly well preserved specimens from the Norian Calcare di Zorzino Formation (Zorzino Limestone) of Lombardy (Northwestern Italy), ascribed to L. pandolfii Renesto, 1994. However, the structure of the skull remained virtually unknown until the discovery of a nearly complete and articulated specimen from the Dolomia di Forni Formation (Forni Dolostone) of Friuli, northeastern Italy (Muscio, 1996). That specimen was assigned to a different species, L. tonelloi Muscio 1996, on the basis of the different proportions between some limb elements. Two further specimens referred to Langobardisaurus were reported from the Dolomia di Forni Formation of Friuli (Renesto et al., 2002; Dalla Vecchia, 2006). A third species, L. rossii, also based on a specimen (MFSN 19235) from the Dolomia di Forni Formation of Friuli, was erected by Bizzarrini and Muscio (1995). However Renesto and Dalla Vecchia (2007) demonstrated that L. rossii is instead a lepidosauromorph, probably a rhynchocephalian; so that Langobardisaurus rossii is an invalid taxon
Establishing phylogenetic relationships of Megachirella wachtleri Renesto & Posenato, 2003 (Reptilia, Diapsida)
No full textA new specimen of Tanystropheus (Reptilia Protorosauria)from the Middle Triassic of Switzerland and the Ecology of the genus
No full textA new specimen of the protorosaurian diapsid reptile Tanystropheus is described. The specimen was collected at the Valle Serrata locality (Switzerland) and is of Ladinian (Middle Triassic) age. Its study elucidates some issues regarding the anatomy of Tanystropheus to be addressed, and allow to suggest hypotheses about its mode of life. In particular, the specimen is the first one in which the skin and other soft tissues can be described. In particular, wide patches of black phosphatic material, filled with small carbonate spherules are preserved, as it occurs in corpses lying in stagnant water due to decomposition of consistent amount of proteins. This suggests that a huge mass of flesh was present in the caudal part of the body, shifting posteriorly the center of mass of the animal and helping in balancing the weight of the neck even if raised off horizontal plane and out of water. In addition, no evidence of caudal autotomy is present in Tanystropheus and the structure of the tail and of the limbs are consistent with a shoreline habitat rather than with a fully aquatic mode of life
PECULIAR PRESERVATION OF A JUVENILE PACHYPLEUROSAURID FROM BESANO (ITALY)
No full textA small pachypleurosaurid collected in the Besano area of Italy, is described. A comparative analysis of size and proportions with other pachipleurosaurids suggest it represents a juvenile specimen of Neusticosaurus pusillus. The specimen represents a peculiar taphonomic case: the centra of the dorsal vertebrae are clustered together in the pectoral area while the rest of the trunk is virtually undisturbed, suggesting that disarticulation of dorsal vertebral elements may have occurred before decay of integumental soft parts, possibly before the carcass reached the bottom of the basin
Remains of a juvenile phytosaur from the Late Triassic of Northern Italy
No full textA series of nine articulated caudal vertebrae collected from the Late Norian Argillite di Riva di Solto Shale (Bergamo, Northern Italy) are described. The caudal vertebrae belong to an archosaur, most probably an immature specimen of the phytosaur Mystriosuchus, as suggested by detailed comparison with the corresponding caudal vertebrae of the adult and complete Mystriosuchus specimen collected in the same area. The new specimen is of particular interest because material unequivocally belonging to juvenile phytosaurs is very rare and it gives support to the hypothesis that the closure of the neurocentral suture in phytosaurs possibly followed the same caudal to cranial path that occurs in crocodilians
Bird-like head on a chameleon body: new specimens of the enigmatic diapsid reptile Megalancosaurus from the Late Triassic of Northern Italy
No full textTwo new Megalancosaurus specimens collected from the Norian (Late Triassic) Calcare di Zorzino (Zorzino Limestone) Formation (Bergamo, Lombardy, Northern Italy), and from the coeval Dolomia di Forni (Forni Dolostone) Formation (Udine, Friuli, North-eastern Italy) improve our knowledge of skeletal anatomy and mode of life of this genus. Morphology of observable skull elements and cervical vertebrae in one of the new specimens shows some resemblance to the possible Triassic bird Protoavis, while the postcranial skeleton of Megalancosaurus is completely non-avian. This may suggest that either Megalancosaurus and Protoavis developed a similar neck structure as a response to the same functional requirement, or that part of the disarticulated material ascribed to Protoavis may indeed belong to a Megalancosaurus-like reptile. Megalancosaurus shows a very high adaptation to arboreal life and a peculiar feeding strategy. Recent suggestions that Megalancosaurus may have been a glider and a possible model for bird ancestry are discussed. Some skeletal features of Megalancosaurus may indeed be interpreted as gliding adaptation, but evidence is weak, and if this reptile was a glider, however, its gliding bauplan should have been completely different from the one usually accepted for bird ancestors, showing instead more morphological similarities with gliding squirrels, phalangeriids and putative ancestors of bats and pterosaurs (according to a non cursorial model for these latter)
A new Prolacertiform reptile from the Late Triassic of Northern Italy
No full textA new diapsid reptile is described from the locality of Cene (Seriana Valley, near Bergamo, Lombardy, Northern ltaly) from an outcrop of the Calcare di Zorzino (Zorzino Limestone) Formation (Middle Norian, Late Triassic). It is based on virtually identical specimens, differing only in size. Analysis of available diagnostic characters allows it to be included in the Prolacertiformes, represenring a new genus and species, Langobardisaurus pandolfi probably related to Macrocnemus, possibly to Cosesaurus, and to the Tanystropheidae. It is assumed here that Langobardisaurus pandolfii was adapted to a terrestrial mode of life and probably to an insectivorous diet
Megalancosaurus, a possibly arboreal archosauromorph (Reptilia) from the Upper Triassic of Northern Italy
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