Team internazionale pubblica lo studio Ondate fredde alla fine del Cretaceo, e poi l’asteroide sulla rivista «Science Adavanced» dove emerge uno scenario in cui brevi inverni vulcanici sovrimposti a una tendenza globale al riscaldamento potrebbero aver deteriorato gli ecosistemi prima dell’asteroide di fine Cretaceo.
La fine dell’era mesozoica, 66 milioni di anni fa, è nota per l’estinzione di massa che colpì i dinosauri, e moltissime altre specie. Due le cause di cui si discute da decenni nella comunità scientifica. L’impatto di un asteroide, detto Chixkulub, di cui è oggi preservato il cratere in Yucatan (Messico), e l’eruzione di un volume anomalo di basalti continentali, detti del Deccan, in un’area corrispondente all’odierna India. In un articolo pubblicato sulla prestigiosa rivista «Science Advances», un team internazionale di geologi e geochimici aiuta a definire meglio il ruolo del vulcanismo, attraverso la ricostruzione dei volumi di gas vulcanici liberati. La ricerca è stata condotta da un team guidato da Sara Callegaro dell’Università di Oslo, di cui fanno parte anche ricercatori delle Università di Padova, Trieste e Napoli, ma anche della McGill (Montreal, Canada), dell’Università della California (Berkeley, USA) e del museo di Storia Naturale di Stoccolma (Svezia).

The best known sauropod dinosaurs were huge herbivorous creatures, whose brain structures were markedly different from those of their evolutionary predecessors, for the earliest representatives of the group were small, lithe carnivores.

The sauropod group of dinosaurs included the largest animals that have ever walked the Earth – up to 40 meters long and weighing as much as 90 tons. Evolutionarily speaking, they were obviously very successful, giving rise to a diverse and widely distributed array of plant-eating species. These forms were characterized by a small head, a long and highly flexible neck that allowed them – like modern giraffes – to graze the tops of the tallest trees, and a massive body that made mature specimens invulnerable to predators. The sauropods survived for well over 100 million years before succumbing to the meteorite that snuffed out the dinosaurs at the end of the Cretaceous Era.

However, the early representatives of the lineage that led to these lumbering giants were strikingly different in form and habits. For a start, they were carnivores – like Saturnalia tupiniquim, an early sauropod dinosaur that was about the same size as a modern wolf. Recent work carried out by researchers for Ludwig-Maxilians-Universitaet (LMU) in Munich in collaboration with colleagues in Brazil now confirms this scenario and adds new details to the story. Most of the evidence for the early members of the Sauropodomorpha comes from their type of dentition. Now paleontologists Mario Bronzati and Oliver Rauhut, who are based at LMU and the Bavarian State Collection for Paleontology and Geology in Munich, have used computer tomography (CT) to analyze fossil skull bones assigned to S. tupiniquim. The high-resolution images of the cranial bones provided by this technique enabled them to deduce the overall surface morphology of the brain. The results suggest that despite being capable of consuming both meat and plants, S. tupiniquim could have followed a purely predatory lifestyle. The new findings appear in Scientific Reports, one of the online journals published by Springer Nature.