The whole set of evolutionary transformations displayed by marine tetrapods constitutes a fascinating research field, where functional aspects overlap e.g. developmental or ecological questions, and where extant forms are a direct clue for a precise biological understanding of fossils. However, this complex subject requests a multidisciplinary approach. In the aim of getting together specialists of the various scientific fields potentially involved, a congress was held in Poitiers (France), as the first step of a series of international meetings on the subject. A second meeting occurred in Copenhagen in 1999. The present book is derived from the meeting of Poitiers, and resumes its fundamental aim: create a broad, unrestricted communication between specialists who seldom have the opportunity to directly exchange knowledge and reflection.

The editors are very grateful to the eighteen outstanding scientists, all being world-known authorities in their speciality, who generously contributed to this work for a total of 19 articles covering all relevant fields. Our wish is that this book will have the same development as the congress from which it is derived, and will be progressively improved and actualised with the progress of research itself.

Contributors 11
Foreword by the editors 13
Physical and Chemical properties, geography and history of seas and oceans
Maxence REVAULT D’ALLONNES: Physical and Chemical properties of the oceans: an overview 15
Eric BUFFETAUT: Earth History as a background to secondary adaptation of tetrapods to life in water 31
Henri L. MASSÉ: Energy fluxes and food webs in seas – On some marine trophic networks 39
Guy DUHAMEL: Extant vertebrates in marine food chains and trophic networks 55
Marine tetrapods and their evolutionary history
Vivian DE BUFFRÉNIL and Jean-Michel MAZIN: What is an aquatic tetrapod? Some introductory remarks 91
Jean-Michel MAZIN: Mesozoic Marine reptiles: an overview 95

Beispielseiten
Georges HÉMERY: Biodiversity and adaptations of extant marine birds: an overview 119

Beispielseiten
Anette Vedding KRISTOFFERSEN: Adaptive specialisation to life in water through the evolutionary history of birds 141
Daryl P. DOMNING: Evolution of the Sirenia and Desmostylia 151
Ewan FORDYCE and Christian DE MUIZON: Evolutionary history of the cetaceans: a review 169
Annalisa BERTA and Peter J. ADAM: Evolution biology of Pinnipeds 235
Adaptive patterns
Frank E. FISH: Mechanism for evolutionary transition in swimming mode by mammals 261
Armand de RICQLÈS & Vivian DE BUFFRÉNIL: Bone histology, heterochronies and the return of Tetrapods to life in water: where are we? 289
Daniel ROBINEAU: Distributional ecology of extant marine mammals 311
Field investigations on the physiology and functional adaptations of marine mammals
Paul F. BRODIE: General introduction 337
Paul F. BRODIE: Field studies of the comparative mechanics of skin and blubber from walrus (Odobenus rosmarus rosmarus) 339
Paul F. BRODIE: Feeding mechanics of rorquals (Balaenoptera sp.) 345
Paul F. BRODIE and Arvid J. PÅSCHE: The mechanics of cetacean respiration: the significance of rapid gas exchanges in a selectively tuned system, with emphasis on the rorquals (Balaenoptera sp.) 353
Paul F. BRODIE and Arvid J. PÅSCHE: Body temperature variation in grey and harbour seals (Halichoerus grypus and Phoca vitulina), based upon post-mortem measurements of young and adult animals 363

The expression secondary adaptation to life in water designates one of the most important evolutionary processes that occurred during the history of the Tetrapods: after the conquest of a terrestrial habitat was completely achieved with the development of the amniotic egg, a significant number of taxa made the reverse way, and re-adapted to the marine environment. Since the Early Triassic (or even the latest stages of the Permian), up to present times, this process involved hundreds of species of reptiles, mammals and birds. These animals could efficiently colonise various ecological niches (most often as predators), and successfully compete with fishes and other animals primarily adapted to life in water.
The degrees of tetrapod re-adaptation to life in the oceans are (and have been in the past) quite variable between species. However, in order to meet the steep constraints of this milieu, adaptive features generally bear on numerous, basic biological characteristics simultaneously: morphology, biomechanics, physiology, behaviour, etc. The whole set of such evolutionary transformations constitutes a fascinating research field, where functional aspects overlap e.g. developmental or ecological questions, and where extant forms are a direct clue for a precise biological understanding of fossils.
The previous remarks lead to an obvious conclusion: the understanding of the secondary adaptation of Tetrapods to life in water, considered as an evolutionary diversification process, requests a multidisciplinary approach.
In the aim of getting together specialists of the various scientific fields potentially involved in the subject, a congress was held in Poitiers (France) in 1996. In agreement with the initial intention of its convenors, this congress was the first step of a series of international meetings: a second edition was held in Copenhagen (Denmark) in September 1999, and others should periodically occur in other countries.
The present book is derived from the meeting of Poitiers. It collects the plenary lectures given at this occasion, together with additional, complementary articles. Therefore, this book resumes the fundamental aim of the congress: create a broad, unrestricted communication between the specialists of different research fields, who seldom have the opportunity to have a direct exchange of knowledge and reflection.
This quest of a dialog has a consequence on the structure of the book itself: it is intended to give accurate, up-dated information, but each of its articles must also be accessible for a non-specialised reader. Hence, the book is neither a popularisation text, nor a mere juxtaposition of self-sufficient scientific contributions: it is rather a synthetic solution between these two extremes.
Eighteen authors, all being world-known authorities in their speciality, have contributed to this book for a total of 19 articles. A complete freedom was let to each of them, but the whole set of articles was conceived and organised so that most of the main approaches relevant to the subject be presented.
The editors are very grateful to each of the outstanding scientists who generously accepted to contribute to this work. Our wish is that our common book will have the same development as the congress from which it is derived, and will be progressively improved and actualised with the progress of research itself. We are also grateful to Sabine Riffaut (University of Poitiers) for her important contribution to the illustration of this book.

The editors
Jean-Michel MAZIN and Vivian de BUFFRÉNIL

Peter J. ADAM, San Diego, USA
Annalisa BERTA, San Diego, USA
Paul F. BRODIE, Halifax, Canada
Eric BUFFETAUT, Paris, France
Vivian DE BUFFRÉNIL, Paris, France
Daryl P. DOMNING, Washington, USA
Guy DUHAMEL, Paris, France
Frank E. FISH, West Chester, USA
Ewan FORDYCE, Dunedin, New-Zealand
Georges HÉMERY, Biarritz, France
Anette Vedding KRISTOFFERSEN, Copenhagen, Denmark
Henri L. MASSÉ, Marseille, France
Jean-Michel MAZIN, Poitiers, France
Christian DE MUIZON, Paris, France
Arvid J. PÅSCHE, Trondheim, Norway
Maxence REVAULT D’ALLONNES, Paris, France
Armand de RICQLÈS, Paris, France
Daniel ROBINEAU, Paris, France

Dr. Jean-Michel MAZIN is a research director in Paleontology at the French Centre National d’Histoire Naturelle, and works at the University of Poitiers, France. He has been involved for many years on the evolutive history of marine reptiles, with a multidisciplinary approch combining taxonomy, functional morphology, biogeography and paleoecology.
E-Mail: jean-michel.mazin@campus.univ-poitiers.fr

Dr. Vivian de BUFFRÉNIL is a research fellow at the Muséum National d’Histoire Naturelle of Paris (France). His contribution to the study of aquatic tetrapods mainly deals with the structural and developmental specialisations of skeletal tissues induced by life in water.
E-Mail: buffreni@mnhn.fr