Voglia di Evoluzione 3 – Evoluzione biologica, evoluzione culturale

Il 17 aprile, a Milano, due interessanti conferenze sull’origine dei tetrapodi con Jennifer Clack dell’Università di Cambridge

«La storia dell’evoluzione ci mostra che la vita sfugge a qualsiasi barriera. La vita finisce sempre col prevalere. La vita dilaga in nuovi territori. Magari con fatica, sfidando il pericolo. Ma la vita è inarrestabile» Ian Malcom, da Jurassic Park – Michael Crichton
17 APRILE 2013 (locandina in allegato)
Università degli Studi di Milano
Via Celoria, 20
Ore 10.30 Aula BS – Seminari – Dipartimento di Bioscienze
Devonian tetrapods and the Origin of Tetrapod Locomotion 
JENNIFER CLACK – Professor and Curator, University Museum of Zoology – University of Cambridge
Introduce e modera: MARCO CASTIELLO
Ore 14.30 Aula 202 – Settore didattico
…E poi tornarono all’acqua – l’origine dei rettili marini
ANDREA TINTORI – Università degli studi di Milano
The End-Devonian Mass Extinction and the Rebuilding of Terrestrial Ecosystems
JENNIFER CLACK – Professor and Curator, University Museum of Zoology – University of Cambridge
Introduce e modera: ANDREA TINTORI – Università degli Studi di Milano
Lecture 1. Devonian tetrapods and the Origin of Tetrapod Locomotion 
Our record of tetrapod taxa from the Late Devonian has expanded greatly in recent years. Two of the best known are Ichthyostega and Acanthostega from Upper Devonian (Famennian) rocks of Greenland. The relative completeness of their skeletal remains has allowed us to gain new insights into how they could move, or rather, not move. Both were to a large extent aquatic animals: Acanthostega was primarily aquatic with little capability of terrestrial locomotion, whereas Ichthyostega was capable of some excursions on land. We used microCT and synchrotron scanning methods to explore the range of motion of the limb joints in Ichthyostega. We showed that it did not ‘walk’ in the traditional sense, but seems to have used a ‘crutching’ motion in which the limbs were used in a way comparable to that of a mudskipper. 
Lecture 2. The End-Devonian Mass Extinction and the Rebuilding of Terrestrial Ecosystems 
At the end of the Devonian, a mass extinction event resulted in the loss of many aquatic vertebrate taxa such as placoderms, many early lobe-finned fishes, and many species of acanthodians. Following this, chondrichthyans and ray-finned fishes radiated, but coelacanths and lungfishes were reduced in diversity. Tetrapods survived, but because of an apparent hiatus in the fossil records, we knew very little about them. By the time they reappear in numbers in the fossil record, in the mid-Carboniferous Visean stage, they are fully terrestrial and diverse. How they evolved from their aquatic predecessors into terrestrial forms was unknown. Recently, new material, of tetrapods, fish, arthropods and plants, from the earliest Carboniferous Tournaisian stage is helping to fill that gap. For example, the earliest known pentadactyl foot has been found, from this time, alongside new tetrapod taxa showing a range of previously unknown morphologies. This ‘work in progress’ heralds fresh understanding of the advent of tetrapods onto land and the establishment of modern-style ecosystems.
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6830.pdf (6 MB)