Irresistible offer to step back in time

The study of fossil footprints and trackways might give the impression of an arcane and esoteric branch of palaeontology. Standing on a quarry floor in Portugal tracing a line of footprints, each the size of a dustbin lid, marching in a straight and determined line as far as the eye can see, brings home the reality. This 147m line of footsteps is the longest known trackway of a plant-eating sauropod dinosaur. The track-maker ambled across a muddy estuary about 160 million years ago. The imprints of its feet are so clearly preserved in the rock that it is almost as though it had walked that way but hours before. Here is a record, set in stone, of the behaviour of an animal that lived an almost unimaginably long time in the past.

Palaeo-ichnologists face difficult problems. Because there are almost no cases of animals dropping dead in their tracks, matching footprints to the feet that made them is not an exact science. So footprints have their own parallel system of scientific names running alongside the ones we use to distinguish fossil species based on their skeletal remains. Footprint data cannot therefore add much to our evolutionary understanding. Footprints and trackways can, however, reveal clues about their owners' way of life that fossil bones cannot, particularly posture, locomotor patterns, speed and behaviour. Martin Lockley has made palaeo-ichnology, particularly the study of dinosaur tracks, his life's work. He has conducted many original research investigations, has written several books and has done much over the past 15 years or so to put tracks firmly on the map.

Dinosaur Tracks and Other Fossil Footprints of Europe , co-authored with Christian Meyer, is a synthesis of the recent findings on European fossil footprints. Amphibian, reptile, bird and mammal tracks are reviewed chronologically through more than 300 million years of vertebrate evolution and placed in the context of Europe's changing environments. The authors have drawn extensively on their own research in Britain, Portugal, Spain, Spitzbergen, Switzerland and elsewhere to synthesise a useful and compact reference work.

The book begins with an "Introduction to tracking", a how-to-do-it guide that discusses how prints are studied and named. The physical mechanisms of preservation and the interpretation of behaviour and ancient environments are other precursors to the bulk of the text that progresses, in sequence, from ancient trails in 370 million-year-old Devonian rocks in Ireland and Scotland through to "The signature of modern humanity".

A large proportion of the text is devoted to dinosaurs, for which the authors make no apology. However, there is much of interest, and the past lives of the track-makers are brought to life quite vividly, none more so than those of the pterosaurs. Pterosaurs, flying reptiles, are not dinosaurs but quite close relatives that lived at the same time. The finding of clear quadrupedal tracks has finally settled a long debate as to how these animals walked. Ideas that they jogged along on their hind legs have been firmly disproved by the waddling four-footed locomotion seen in every recognised pterosaur track.

Lockley and Meyer conclude with an appendix that covers the places to see tracks and prints across Europe, with brief guidelines on major sites, exhibitions and the best locations to explore for prints. There is but half a page devoted to England (on which are listed some Scottish museum exhibits!) and readers will find the information rather too brief to set out on a tracking expedition.

This book serves a range of audiences including professional palaeontologists and geologists, students and anyone with more than a passing interest. It fills an admirable niche as an up-to-date European ichnological reference resource. It is crisply designed, well illustrated and comprehensively referenced. The house reference style is rather irritating: instead of a standard scientific reference format, there are numbered bibliographic notes at the end of each chapter from which the reader has to go to the main reference list to pick up the details.

Lockley's single-authored book is a different offering. It is ostensibly aimed at the popular-science market. The organisation of the subject matter is again basically chronological, but it begins further back in time with Cambrian invertebrates and ends with the tracks made by the Viking I Mars lander. Lockley draws on examples from tracks and trails around the world, again with the emphasis on dinosaurs, mammals and hominids. The chapters are broken into short essays, each prefaced with literary quotations ranging from Einstein to Winnie-the-Pooh. Much of this is an interesting read. Examples of modern trackways and prints of mammals are used to illustrate their behaviour, making it easier to see how this can be applied to fossils.

There are some fascinating human stories, too. Lockley describes the discovery of some of the aforementioned tracksites in Portugal, and the sheer tenacity of scientists dedicated to the preservation of natural history sites. It is easy to predict the probable outcome of a campaign to preserve a sauropod trackway discovered in the path of a proposed motorway extension on the outskirts of London. The outcome of exactly that situation on the outskirts of Lisbon was a massively expensive road tunnel under the trackway site.

Lockley has also used this book to expound his philosophical, psychological and spiritual leanings. He believes "the eternal trail leads from the simple unselfconscious beginnings of the biosphere to its fully conscious maturation to the birth of the noosphere". He tries to weave together an evolutionary narrative with his very individual mystic views. Frankly, this detracts from what could otherwise be a very recommendable read. A sudden lurch from sauropod tracks in Texas to the probable cyclic nature of the universe is confusing. Science, evolution, mysticism and spiritual awareness make an odd mix that leaves a rather baffling sense of what this book is really about.

Angela C. Milner is head of the fossil vertebrate and anthropology division, Natural History Museum, London.