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The late Early Pleistocene was the last time of equable climate in northern Central Italy, reflected in its large mammal fauna and numerous palynological records. Reliably dated leaf fossils from this time are rare, but provide crucial information onlocal and regional vegetation, biogeographic relationships, and species turnover coinciding with the assembly of modern forest biomes. Here we investigated a rich assemblage of leaf and fruit impressions (63 fossil-taxa) from the Oriolo quarry, Faenza (Ravenna), dated to the latest Calabrian, preserved in transgressive coastal deposits. The fossil assemblage represents riparian vegetation and xeric alluvial habitats in the lowlands and forest vegetation above the alluvial plain. Forest-building trees were deciduous, but comprised several taxa characteristic of open scrubland or forest edges. The composition of the flora reflects a dynamic process of assembling modern forest biomes in western Eurasia. While most taxa correspond to modern submediterranean and temperatewoody species, some others represent late occurrences of taxa today confined to refugia outside Italy (Parrotia, Gleditsia, Pterocarya), and a few are Miocene/Pliocene relics indicating final floristic links with East Asia (Japan) and/or North America (Tsuga cf.chiarugii, Carya cf. minor) and Pleistocene endemism in Italy (Berberis auriolensis, Acer aemilianum).

Evidence from various climate proxies provides us with increasingly reliable proof that only in the past 10 millennia were natural systems more or less as we see them at the present (without considering human impact). Prior to 10,000 years ago, natural systems repeatedly changed under the influence of an unstable climate. This is particularly true over the last one million years. During these times, terrestrial environments were populated by a diversity of large animals that did not survive either the last dramatic climate change or the increasing power of humans. The volume of continental ice covering the land and its impact on the planet’s physiography∗ and vegetation have varied consistently. We can try to imagine extreme conditions: the very cold springtimes of the full glacials∗, and the warm springtimes of the rapid deglaciation phases, with enormous volumes of water feeding terrifying rivers. Most of this story is frozen in the ice cover of Greenland and Antarctica, the deep layers of which have been reached by human coring activities only over the past half century. Shorter cores have been drilled in high-altitude ice caps (e.g., in the Andes) that provide insight into other parts of the planet. The interpretation of the signals locked into the ice cores led to the reconstruction of climatic curves covering approximately the past 800 millennia. In addition, long sediment cores have been recovered from thousands of lakes across the globe and yielded data useful to estimate climatic trends based on pollen* records. In the past one to three million years, the continents and oceans were in roughly their present-day locations. Environmental factors, including tectonics (mountain uplift or closure of ocean gateways), interacted with the overall long-term oscillation in atmospheric carbon-dioxide concentration, which, in turn, influenced vegetation cover and ecosystem composition. Well-established glacial-interglacial∗ cycles impacted biotic dispersal∗ events at mi

We continue our trip back in time through the Mesozoic, visiting several different ecosystems across the planet. Each of these was strongly influenced by the continental breakup from a single landmass into several tectonic plates and associated landmasses during this period. We will visit localities on several continents, observe how their vertebrate faunas changed over time, and what external factors might have contributed to these differences. During the Cretaceous, we visit the Iberian Peninsula, where hadrosauroids replaced titanosaurs as the most abundant dinosaur taxon. On the other side of the planet, a succession of geologic formations in Australia shows a gradual change from aquatic to terrestrial faunas resulting from sea-level changes of a now non-existent inland ocean. A visit to two polar ecosystems indicates possible mutual exclusion between amphibians (temnospondyls) and reptiles (crocodylomorphs), because they occupied similar ecological niches. Observing the record of Cretaceous landscapes in what is now Mongolia shows how changes in environment and climate correlate with changes in faunal composition. Heading back, we check if there are distinct differences in vertebrate diversity in space and time in the Late Jurassic of North America. Then we move south, to Argentina, and back to the Middle and Early Jurassic. Here, we will try to understand where these Late Jurassic faunas originated and what influence the fragmentation of the supercontinent Pangea had on their evolution and diversity. Finally, we will stop our trip in the Late Triassic of Central Europe, examining a typical vertebrate fauna from the time when dinosaurs began their domination of the planet.

If we imagine walking through Mesozoic lands, we would be able to observe vertebrates with peculiar combinations of morphological traits, some of which would seem to be intermediary to animals seen today. We would witness a terrestrial vertebrate fauna dominated by dinosaurs of various sizes and diversity, accompanied by many other animal groups that often are overlooked. Current research suggests that many of the main vertebrate clades existing today originated or diversified sometime in the Triassic or Early to Middle Jurassic. Herein, we profile some of the major transformations in both terrestrial and aquatic vertebrate evolution during the Mesozoic. We highlight: the appearance of features that allowed sauropod dinosaurs to become the largest animals to ever walk on Earth’s continents, the appearance of herbivory among the usually carnivorous theropod dinosaurs, and we follow the specific changes that led to the evolution of avian flight. Our Mesozoic tour across the globe will allow us to see how different evolutionary forces led to convergent shifts to quadrupedality in ornithischian dinosaurs and to an aquatic lifestyle in turtles, crocodiles, and plesiosaurs. Last, but not least, we examine changes in the Mesozoic fauna linked to the rise of mammals, and the diversification patterns in several clades of fishes after the End-Permian Mass Extinction.

The most accepted killing model for the Permian-Triassic mass extinction (PTME) postulates that massive volcanic eruption (i.e., the Siberian Traps Large Igneous Province) led to geologically rapid global warming, acid rain and ocean anoxia. On land, habitable zones were drastically reduced, due to the combined effects of heating, drought and acid rains. This hyperthermal had severe effects also on the paleobiogeography of several groups of organisms. Among those, the tetrapods, whose geographical distribution across the end-Permian mass extinction (EPME) was the subject of controversy in a number of recent papers. We here describe and interpret a new Early Triassic (?Olenekian) archosauriform track assemblage from the Gardetta Plateau (Briançonnais, Western Alps, Italy) which, at the Permian-Triassic boundary, was placed at about 11° North. The tracks, both arranged in trackways and documented by single, well-preserved imprints, are assigned to Isochirotherium gardettensis ichnosp. nov., and are here interpreted as produced by a non-archosaurian archosauriform (erytrosuchid?) trackmaker. This new discovery provides further evidence for the presence of archosauriformes at low latitudes during the Early Triassic epoch, supporting a model in which the PTME did not completely vacate low-latitude lands from tetrapods that therefore would have been able to cope with the extreme hot temperatures of Pangaea mainland.