BIRD-LIKE HEAD ON A CHAMELEON BODY: NEW SPECIMENS OF THE ENIGMATIC DIAPSID REPTILE MEGALANCOSAURUS FROM THE LATE TRIASSIC OF NORTHERN ITALY

Two 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).&nbsp

BIRD-LIKE HEAD ON A CHAMELEON BODY: NEW SPECIMENS OF THE ENIGMATIC DIAPSID REPTILE MEGALANCOSAURUS FROM THE LATE TRIASSIC OF NORTHERN ITALY

Two 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).&nbsp

Cretaceous plesiosaur remains (Reptilia, Sauropterygia) from the Argille Varicolori of Varzi (Pavia, Lombardy, Northern Italy)

The first finding of a plesiosaur in Italy is reported. The specimen, a single humerus has been collected in the Argille Varicolori formation, in an outcrop close to the village of Zavattarello. Micropaleontological dating indicates a Santonian-Campanian age for the sediment enclosing the fossil. The morphology of the bone is described. -from Autho

STRUCTURE OF THE TAIL OF A PHYTOSAUR (REPTILIA, ARCHOSAURIA) FROM THE NORIAN (LATE TRIASSIC) OF LOMBARDY (NORTHERN ITALY)

The structure of the caudal portion of a vertebral column belonging to a complete phytosaur skeleton is described. The skeleton has been collected from the Calcare di Zorzino (Zorzino Limestone) of Norian (Late Triassic) age, in the small quarry of Endenna (Bergamo, Lombardy, Northern Italy). The specimen is currently being prepared, and only a detailed description of the tail is possible. The exposed portion of the skull, which shows, among other characters, a narrow, flattened snout, suggests possible relationships with the genus Mystriosuchus, but preparation of the skull must be finished prior to attempting any classification. The morphology of the tail vertebrae has never been figured for phytosaurs; however, the structure of the tail vertebrae of this specimen reflects a great degree of adaptation toward aquatic life, justifying its description prior to complete preparation. If this specimen represents a new species, it should have been highly specialised toward marine life than most other phytosaurs in which the postcranial skeleton is known.&nbsp

Co-occurrence of Neusticosaurus edwardsii and N. peyeri (Reptilia) in the Lower Meride Limestone (Middle Triassic, Monte San Giorgio)

A newly opened excavation in the Cassina beds of the Lower Meride Limestone (Monte San Giorgio UNESCO World Heritage List, Canton Ticino, Switzerland), has yielded a pachypleurosaurid (Reptilia: Sauropterygia) specimen which is identified as Neusticosaurus peyeri. The resulting co-occurrence of N. peyeri and N. edwardsii, the latter so far regarded as the sole species of the genus present in this horizon, challenges the hypothesis of a single anagenetic lineage in Neusticosaurus species from Monte San Giorgio. In addition, it leads to a reconsideration of the phylogenetic inferences about Neusticosaurus evolution in the Monte San Giorgio area. The stratigraphic distribution of the Neusticosaurus species in the Monte San Giorgio basin is updated on the basis of recent find

A COMPLETE SPECIMEN OF MYSTRIOSUCHUS (REPTILIA, PHYTOSAURIA) FROM THE NORIAN (LATE TRIASSIC) OF LOMBARDY (NORTHERN ITALY)

A complete and nearly articulated new phytosaur specimen is described in detail. The skeleton, about 4 metres long, has been collected from the uppermost level of the Calcare di Zorzino (Norian, Upper Triassic) in the small quarry of Endenna (Bergamo, Northern Italy). Available characters of the skull allow assignment of this long snouted, uncrested phytosaur to Mystriosuchus planirostris Von Meyer 1863. The postcranial anatomy, detailed here for the first time for this species, suggests a stronger adaptation to aquatic life in Mystriosuchus than in other phytosaurs, and may increase available data to improve our knowledge of the systematic relationships among phytosaurs. The discovery of this nearly complete skeleton in a marine intraplatform basin suggests that a short post-mortem transport of the carcass occurred and thus this phytosaur may have lived whether in a fresh water environment or in a shallow marine habitat, close to emerged lands.&nbsp

EVIDENCES FOR A SEMI AQUATIC LIFE STYLE IN THE TRIASSIC DIAPSID REPTILE TANYSTROPHEUS

The paleoecology of the bizarre, long-necked tanystropheid diapsid Tanystropheus from the Middle and Late Triassic of Western and Eastern Tethys has been debated since the first discoveries. In the present work, osteological features related with gait and locomotion are reanalysed, and a reconstruction of the pattern of the musculature of the tail, pelvic girdle and hindlimb is proposed. The anatomical correlates, along with the inferred functional interpretation of the musculature support the hypothesis that 1) Tanystropheus was able to lift the body off the substrate when on land, 2) it lacked adaptations for continuous swimming, either tail-based or limb-based, 3) it was able to swim for by rowing with symmetrical strokes of the hind limbs. Rowing is a discontinuous swimming pattern that occurs in animals with a semi-aquatic life style which return frequently to emerged land, thus the proposed model is consistent with the hypothesis that Tanystropheus was a shoreline dweller rather than a fully aquatic animal

Differences in the hindlimb anatomy in the two species of the late triassic Drepanosauromorph diapsid Megalancosaurus indicate habitat partitioning within the arboreal environment

Discovery of two different morphologies of the hindlimb in specimens ascribed to the Triassic drepanosauromorph diapsid Megalancosaurus led to the erection of two distinct species within this genus: M. preonensis and M. endennae. In the present study a re-examination of the hindlimb architecture of both Megalancosaurus species indicates that M. preonensis and M. endennae exploited different microhabitats within the arboreal environment as for many extant species belonging to the same genus, like caribbean Anoles. M. endennae, with a stronger lower leg, a larger grasping foot, an opposable clawless hallux, and deeper and more recurved claws on pedal digits 2-5 was better adapted for locomotion on narrow and intricate supports like narrow twigs on terminal branches. M.preonensis with more slender hindlimbs, absence of an opposable hallux and longer, but thinner and less recurved claws on all pedal digits may have been better adapted to live on larger supports and could also have used the long pedal claws as hooks in a sloth-like fashion. In both Megalancosaurus species the tail acted both as a prop to assume a stable tripodal gait and as a clinging device that ensured grip during bridging as in other arboreal drepanosauromorphs which skeleton is adequately known. The overall hindlimb adaptation of Megalancosaurus species are more similar to that of some small arboreal mammals rather than that of chameleons

A REVIEW OF RHYNCHOSAUROIDES TIROLICUS ABEL, 1926 ICHNOSPECIES (MIDDLE TRIASSIC: ANISIAN-LADINIAN) AND SOME INFERENCES ON RHYNCHOSAUROIDES TRACKMAKER

Rynhcosauroides tirolicus (Abel, 1926) is the first ichnite of Triassic tetrapods known from the South-eastern Alps. The recent discovery of new tracks and trackways also permits, for the first time, the documentation of trackway pattern and to calculate the dimensions and possible functional dynamics of the author of this form which appears peculiar to the upper Anisian deposits of the Southern Alps. A tentative palaeontological attribution of Rhynchosauroides tirolicus and other Middle Triassic Rhynchosauroides trackmaker suggest with some confidence, that the morphology of the trackmakers matches the structure of prolacertiform reptiles like Macrocnemus bassanii Nopcsa, 1931 if this latter is reconstructed with a not fully plantigrade manus and pes, but rather with a semi-plantigrade manus and a digitigrade pes.

A COMPLETE SPECIMEN OF MYSTRIOSUCHUS (REPTILIA, PHYTOSAURIA) FROM THE NORIAN (LATE TRIASSIC) OF LOMBARDY (NORTHERN ITALY)

A complete and nearly articulated new phytosaur specimen is described in detail. The skeleton, about 4 metres long, has been collected from the uppermost level of the Calcare di Zorzino (Norian, Upper Triassic) in the small quarry of Endenna (Bergamo, Northern Italy). Available characters of the skull allow assignment of this long snouted, uncrested phytosaur to Mystriosuchus planirostris Von Meyer 1863. The postcranial anatomy, detailed here for the first time for this species, suggests a stronger adaptation to aquatic life in Mystriosuchus than in other phytosaurs, and may increase available data to improve our knowledge of the systematic relationships among phytosaurs. The discovery of this nearly complete skeleton in a marine intraplatform basin suggests that a short post-mortem transport of the carcass occurred and thus this phytosaur may have lived whether in a fresh water environment or in a shallow marine habitat, close to emerged lands.&nbsp