I am pleased to be able to introduce this book by Monsieur lean-Claude Gall, firstly because it is a book, secondly because its author has been a colleague for 15 years, and finally because it is a book which demonstrates the growing importance of Palaeobiology. "Because it is a book". I have already commented else­ where on the value which the Earth Science community places on a book. And here I am speaking, not of a thesis or a specialised memoir, which are always precious, but of a manual or text, which draws on the experts in the service of all. In the years preceding and following the Second World War, the number of "books" written by French geologists could be counted on the fingers of one hand. Today I am happy to see that the number of geological "books" is increas­ ing in France, taking the word "geology" in its broadest sense. This I see as a sign of the growth of the Earth Sciences.