Tall story: the tale of a tail:Books

SEISMOSAURUS: THE EARTH SHAKER BY DAVID D. GILLETTE Columbia University Press, 205pp, Pounds 26.50 ISBN 0 231 07874 9

Americans frequently claim to produce the biggest, fastest or whatever superlative one cares to apply, in most walks of life. In the case of dinosaurs this undoubtedly holds true. Seismosaurus hallorum whose discovery, in New Mexico in 1979, and subsequent scientific investigation is the subject of this book, was of truly earth-shaking proportions at somewhere between 39 and 52 metres long and weighing perhaps up to 100 tonnes.

Seismosaurus: the Earth Shaker is a case study of just one single dinosaur skeleton. The author, David Gillette, currently Utah's state palaeontologist, has written a first-person account of the project that is highly readable. It answers along the way many of the questions asked of any major new dinosaur discovery. What makes this one so notable is, of course, its sheer size. The specimen was first discovered by two hikers who stumbled across a line of tail bones in a remote desert area of central New Mexico.

Gillette devotes a good part of the book to the subsequent excavation of the partial articulated skeleton over a ten-year period. The problems were enormous and labour intensive, the organisation of dedicated teams of volunteers a logistical nightmare and the tale of the tail unfolds with wit and anecdotes.

The range of techniques used, from the jackhammer to the use of sophisticated ground penetrating radar to detect the extent and depth of the dinosaur's remains, are explained in a detailed but totally accessible language for non-palaeontologists. This is no dry and dusty account but an exciting detective story of up-to-date scientific discovery and technology, plus a measure of seat-of-the-pants inventions in the field, that leaves one quite exhausted at the thought of digging up and transporting five-tonne blocks of bones.

Seismosaurus belongs to the group of plant-eating dinosaurs called sauropods. It is a close relative of the more familiar Diplodocus whose impressive skeleton greets visitors to London's Natural History Museum. Gillette admits that there are some friendly rival claims between the scientists who study these vast beasts as to which ones hold the records. He examines all the giants; which really was the largest -- Seismosaurus, Supersaurus, Ultrasaurus, Dystylosaurus or Brachiosaurus (your children will undoubtedly be familiar with all the names if not the answer). Gillette concludes, in as sober and sensible a manner as is possible when dealing with animals which can be measured in football pitch length terms, that Seismosaurus is the longest dinosaur yet known to science. Calculations based on Seismosaurus's remains suggest that 46 metres is a reasonable estimate within the possible range of 39 to 52 metres.

Alas, the skeleton is far from complete so the bones that are represented have been scaled against other sauropods. Whether it is the largest in terms of mass is much more conjectural especially since all of the other supergiants except for Brachiosaurus are known from just a few bones. Gillette reminds us that it is highly unlikely that the very small sample known represents the largest individuals that ever lived.

Other fascinating aspects of this scientific study hold the reader's attention. How did this gigantic animal die and how did it come to reveal some of its secrets 150 million years later? Collaboration between palaeontologists and chemists led to new evidence as to how bone is fossilised and preserved. In Seismosaurus' case the preservation was so good that proteins were recovered -- the first recognition of organic material from a dinosaur.

Clues to its feeding habits followed the discovery of two clusters of smoothly polished stones up the size of a grapefruit -- 240 stones in all, associated with the skeleton. These stones, called gastroliths, are scaled-up versions of budgie grit and are presumed to have performed the same function -- grinding up tough plant material in a muscular gizzard. Seismosaurus yielded the first accurate estimate of the numbers and volume of gastroliths from a large sauropod.

This is not yet another dinosaur book in the usual mould, but a very user-friendly account of a palaeontologist at work, the thought processes, principles, practices and application of state-of-the-art scientific technology that are involved in studying dinosaurs.

The fact that it chronicles the largest land animals yet known adds yet more appeal. The book is beautifully produced, copiously illustrated with a combination of diagrams, colour photographs and artwork. One of the leading dinosaur artists, Mark Hallett, created some superb recreations of Seismosaurus the herd ambling across the dust jacket is stunning.

The story of Seismosaurus should appeal to anyone with an interest in natural history, geology and dinosaurs. It is also an essential addition to professional libraries; much of the information is presented here for the first time and is not yet available in the technical literature.

Angela Milner is head of the fossil vertebrates and anthropology division, department of palaeontology, Natural History Museum, London.