ORIGIN AND EVOLUTION OF THE METAZOA, edited by Lipps, J. H. and Signor, P. W. Plenum Press, New York and London, 1992 xiii + 570 pp. ISBN 0 306 44067 9, $95, ($114 outside USA and Canada) IN THE SHADOW OF THE DINOSAURS: EARLY MESOZOIC TETRAPODS edited by Nicholas C Fraser and Hans-Dieter Sues. The Cambridge University Press, New York and Cambridge 1994, x + 435pp. ISBN 0-521-45242-2. Hardback £50.