Massimo Bernardi

The Origin and Early Radiation of Archosauriforms: Integrating the Skeletal and Footprint Record.

We present a holistic approach to the study of early archosauriform evolution by integrating body and track records. The ichnological record supports a Late Permian–Early Triassic radiation of archosauriforms not well documented by skeletal material, and new footprints from the Upper Permian of the southern Alps (Italy) provide evidence for a diversity not yet sampled by body fossils. The integrative study of body fossil and footprint data supports the hypothesis that archosauriforms had already undergone substantial taxonomic diversification by the Late Permian and that by the Early Triassic archosauromorphs attained a broad geographical distribution over most parts of Pangea. Analysis of body size, as deduced from track size, suggests that archosauriform average body size did not change significantly from the Late Permian to the Early Triassic. A survey of facies yielding both skeletal and track record indicate an ecological preference for inland fluvial (lacustrine) environments for early archosauromorphs. Finally, although more data is needed, Late Permian chirotheriid imprints suggest a shift from sprawling to erect posture in archosauriforms before the end-Permian mass extinction event. We highlight the importance of approaching palaeobiological questions by using all available sources of data, specifically through integrating the body and track fossil record.

LOCOMOTOR BEHAVIOR IN EARLY REPTILES: INSIGHTS FROM AN UNUSUAL ERPETOPUS TRACKWAY

Abstract An Erpetopus trackway recorded in the Lower Permian Collio Formation (Orobic Alps, northern Italy) is investigated as a source of data to reconstruct ancestral patterns of locomotion in eureptiles. The inferred small-sized captorhinid-“protorothyridid” producer cut an inclined muddy surface dragging its front limb digits, tail, and belly on the ground. Integrating ichnological and anatomical data we suggest that small captorhinids (“protorothyridids”) locomotion was performed with an obligatory, rigid sprawling posture with the trunk only slightly lifted from the substrate in a low, sprawled ‘belly walk’.

Echinoid burrow Bichordites monastiriensis from the Oligocene of NE Italy

Several specimens of trace fossil Bichordites monastiriensis were discovered in two shallow water Oligocene sandstone beds from Valsugana (Trentino, NE Italy) representing the oldest documented occurrence for this ichnospecies. They are grazing-crawling (pascichnion-repichnion) structures and are occasionally associated with enlarged structures that can be interpreted as resting traces (cubichnia) and assigned to the ichnogenus Cardioichnus. The resulting Bichordites—Cardioichnus compound trace fossil is here described for the first time. In the basal part of some specimens, skeletal remains of Eupatagus ornatus were found in life position. This founding enables to widen the spectrum of known Bichordites trace-makers. Exceptional conditions of preservation of one specimen extending in two beds recording different environmental conditions gave an opportunity to document the effects of various taphonomical histories on the preservation of this traces.

Dinosaur tracks in a marginal marine environment: the Coste dell'Anglone ichnosite (Early Jurassic, Trento Platform, NE Italy)

Bipedal tridactyl dinosaur footprints dominate the Early Jurassic Coste dell’Anglone tracksite, located on the eastern slope of the Mt. Biaina-Mt. Brento chain (Trentino Alto-Adige, NE Italy). The site yielded 544 tridactyl footprints, arranged in 20 long trackways, and belongs to the upper part of the Calcari Grigi Group (lower portion of the Rotzo formation). All the tracks can be attributed to smalland medium-sized theropods. Trace fossils were discovered in a peri tidal carbonate succession deposited in a marginal area of the Trento carbonate Platform, which has so far been considered fully marine (subtidal) in origin. The Coste dell’Anglone outcrop represents one of the most extensive Early Jurassic dinosaur tracksites in the Southern Alps and is probably the last dinosaur occurrence on the Trento Platform. The ichnological and sedimentological analyses of the track-bearing sequence indicate a depositional setting corresponding to a tidal flat embayment, positioned on the westernmost sector of the Trento Platform, close to the Lombardy pelagic basin. Stratigraphical data indicate that dinosaur populations lived in this area until the Sinemurian. A comparison with the Early Jurassic theropod tracks global record is here provided, along with an investigation into the possible trackmaker. The tracks share unambiguous similarities with the tridactyl tracks discovered at the Lavini di Marco tracksite, in the basal portion of the Calcari Grigi Group (Monte Zugna formation, Hettangian) and with theropod tracks from the Lower Jurassic of Poland, France and the United States. This new discovery therefore supports calls for a re-examination of the palaeogeographic reconstruction of the Southern Alps during the Early Jurassic

On site DNA barcoding by nanopore sequencing

Biodiversity research is becoming increasingly dependent on genomics, which allows the unprecedented digitization and understanding of the planet’s biological heritage. The use of genetic markers i.e. DNA barcoding, has proved to be a powerful tool in species identification. However, full exploitation of this approach is hampered by the high sequencing costs and the absence of equipped facilities in biodiversity-rich countries. In the present work, we developed a portable sequencing laboratory based on the portable DNA sequencer from Oxford Nanopore Technologies, the MinION. Complementary laboratory equipment and reagents were selected to be used in remote and tough environmental conditions. The performance of the MinION sequencer and the portable laboratory was tested for DNA barcoding in a mimicking tropical environment, as well as in a remote rainforest of Tanzania lacking electricity. Despite the relatively high sequencing error-rate of the MinION, the development of a suitable pipeline for data analysis allowed the accurate identification of different species of vertebrates including amphibians, reptiles and mammals. In situ sequencing of a wild frog allowed us to rapidly identify the species captured, thus confirming that effective DNA barcoding in the field is possible. These results open new perspectives for real-time-on-site DNA sequencing thus potentially increasing opportunities for the understanding of biodiversity in areas lacking conventional laboratory facilities.

The Mesozoic Vertebrate Radiation in Terrestrial Settings

In the last three decades vertebrate ichnology went through a renaissance due the discovery of new tracksites and the application of rigorous analytic methods (e.g., synapomorphy analyses). This finally allowed full hypothesis testing and a better integration of vertebrate ichnology in paleobiologic, paleoecologic and paleobiogeographic studies. In this chapter we provide a review of recent advances in vertebrate ichnology, focusing on Mesozoic terrestrial reptiles.

Dinosaur footprints as ultimate evidence for a terrestrial environment in the late Sinemurian Trento Carbonate Platform

ABSTRACT Three dinosaur footprints were found, preserved as natural casts, on the roof of a First World War tunnel in the Pasubio Massif (Trentino Alto-Adige, northeastern Italy). The Austro-Hungarian Army used the tunnel until 1918, presumably to connect the front- with the back line. The tracks are tridactyl, two of which are organized in a trackway, and provide evidence for the presence of medium-sized theropods. The track-bearing horizon is situated at the base of the Rotzo formation (Calcari Grigi Group), within shallow-water black shale deposits characterized by oligotypic small bivalves, oligohaline ostracodes, and thecamebians. Vertebrate remains, represented by crocodyloform teeth and fish scales, were also identified from the same stratigraphic portion. The occurrence of dinosaur footprints from black shale levels sheds light on their controversial interpretation, confirming the occurrence of terrestrial environment in the Trento carbonate platform during the late Sinemurian. Dinosaur tracks indicate the emersion of a sector of the tidal flat during the deposition of the basal Rotzo formation, and suggest a complex paleonvironmental scenario in which tidal flats were associated with freshwater ponds and islands.

Dinosaur diversification linked with the Carnian Pluvial Episode

Dinosaurs diversified in two steps during the Triassic. They originated about 245 Ma, during the recovery from the Permian-Triassic mass extinction, and then remained insignificant until they exploded in diversity and ecological importance during the Late Triassic. Hitherto, this Late Triassic explosion was poorly constrained and poorly dated. Here we provide evidence that it followed the Carnian Pluvial Episode (CPE), dated to 234–232 Ma, a time when climates switched from arid to humid and back to arid again. Our evidence comes from a combined analysis of skeletal evidence and footprint occurrences, and especially from the exquisitely dated ichnofaunas of the Italian Dolomites. These provide evidence of tetrapod faunal compositions through the Carnian and Norian, and show that dinosaur footprints appear exactly at the time of the CPE. We argue then that dinosaurs diversified explosively in the mid Carnian, at a time of major climate and floral change and the extinction of key herbivores, which the dinosaurs opportunistically replaced.Dinosaurs originated ~245 million years ago (mya) but did not diversify until some time in the Late Triassic. Here, Bernardi and colleagues synthesize palaeontological and dated stratigraphic evidence to show that dinosaur diversification followed the Carnian Pluvial Episode 234–232 mya.

Il concetto di specie e la paleontologia: una rassegna introduttiva

The species is the fundamental unit, reference for all biological classifications and for past and present biodiversity analysis. In practice, species seem to be often (but non always) easily identifiable. There is, however, poor agreement on a definition of this concept. Different views on various issues have led to a proliferation of species concepts, particularly in recent years. In this contribution we present an overview of the most controversial points, the proposed solutions, and their formalization in alternative definitions. Special attention is given to the fossil species debate by reviewing the main contributions published on the topic: from the first symposium dedicated to the species problem in palaeontology, to the definition of units of representation, through the most popular species concept that have been used in palaeontology.

Phylogenetic Stability, Tree Shape, and Character Compatibility: A Case Study Using Early Tetrapods

Phylogenetic tree shape varies as the evolutionary processes affecting a clade change over time. In this study, we examined an empirical phylogeny of fossil tetrapods during several time intervals, and studied how temporal constraints manifested in patterns of tree imbalance and character change. The results indicate that the impact of temporal constraints on tree shape is minimal and highlights the stability through time of the reference tetrapod phylogeny. Unexpected values of imbalance for Mississippian and Pennsylvanian time slices strongly support the hypothesis that the Carboniferous was a period of explosive tetrapod radiation. Several significant diversification shifts take place in the Mississippian and underpin increased terrestrialization among the earliest limbed vertebrates. Character incompatibility is relatively high at the beginning of tetrapod history, but quickly decreases to a relatively stable lower level, relative to a null distribution based on constant rates of character change. This implies that basal tetrapods had high, but declining, rates of homoplasy early in their evolutionary history, although the origin of Lissamphibia is an exception to this trend. The time slice approach is a powerful method of phylogenetic analysis and a useful tool for assessing the impact of combining extinct and extant taxa in phylogenetic analyses of large and speciose clades.