IT鈥橲 a bit ironic that so much dosh is being spent grubbing about for any sign of life on Mars when we still have only a vague inkling of the life that once existed on Earth. Only a few hundred thousand fossil species have been described for the more than 3.8 billion years that life has been around on our planet 鈥� less than 0.01 per cent of species that have existed.
Biologists have plenty to catch up on, and palaeontologists have only begun to scratch the surface. Edward Petuch鈥檚 Cenozoic Seas reviews 4000 so-called 鈥渋ndex鈥� species of mollusc that characterised the amazingly diverse marine communities of eastern North America over the past 35 million years.
For the less specialised fossil enthusiast and student, PaleoBase opens a new window on the fossil record. Based on the superb fossil collections of London鈥檚 Natural History Museum it is a developing digital database, and is revolutionising the teaching of palaeontology. Part 1.0 on arthropods is already out, and Part 2.0 has a wealth of up-to-date information plus 800 images of more than 300 fossil molluscs 鈥� clams, snails and so on. There will be three macrofossil CDs, and one on microfossils.
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Scratching about in the ancient rock strata of southern China is also producing a fossil bonanza, wonderfully illustrated in Cambrian Fossils of Chengjiang. Mainly intended for professional palaeontologists, this spotter鈥檚 guide details the amazing fossils, 525 million years old, that have been shaking the tree of life for the past 10 years. Chengjiang鈥檚 hundred species, from algae to chordates, challenge North America鈥檚 Burgess Shale fauna for the quality and amount of new information they provide.
For more glimpses through Chengjiang-like windows at exceptionally well-preserved past life, read Paul Selden and John Nudds鈥� Evolution of Fossil Ecosystems. This excellent book describes and illustrates 14 sites that range over about 560 million years, from the Ediacara Hills and the Burgess Shale through to Los Angeles鈥檚 Rancho La Brea. It鈥檚 just the job for students and teachers. Indeed, Evolution of Fossil Ecosystems is based on an undergraduate course and a new gallery at the Manchester Museum in the UK. The general fossil enthusiast will get a lot from this Michelin-style guide to some of the world鈥檚 best fossil sites.
Caves are another niche that preserves important information about climates of the not-too-distant past and about contemporary land animals that are not normally fossilised. In Europe we tend to think of humans, bears and perhaps lions as the only large cave dwellers of the past. Ice Age Cave Faunas of North America reminds us that tapirs and ground sloths were also common troglodytes. The first of the continent鈥檚 fossil ground sloths was reported from a cave site in 1799 by that great American polymath and statesman Thomas Jefferson.
One of today鈥檚 big palaeontological debates focuses on whether the so-called molecular clock works better than the fossil record in telling evolutionary time. Here the big idea is that by measuring the genetic differences between two organisms (assuming a given rate of genetic change), it should be possible to estimate when the taxa diverged in the geological past. Telling the Evolutionary Time contains 12 academic essays that are essential reading on this important and controversial topic. According to Philip Donoghue and Paul Smith, the molecular clock implies that 鈥渢he fossil record is not just incomplete, but represents only half of evolutionary history, and the latter half at that鈥�. Are they right? Might the Martian fossil record be better?
Cenozoic Seas by Edward J. Petuch, CRC Press, $189.95, ISBN 0849316324
PaleoBase: Macrofossils part 2.0. edited by Norman MacLeod, Blackwell, 拢29.99/$50, ISBN 0632058919
Cambrian Fossils of Chengjiang, China by Hou Xian-Guang and others, Blackwell, 拢60, ISBN 1405106735
Evolution of Fossil Ecosystems by Paul Selden and John Nudds, Manson, 拢19.95, ISBN 1840760419
Ice Age Cave Faunas of North America edited by Blaine Schubert and others, Indiana, $65, ISBN 0253342686
Telling the Evolutionary Time: Molecular clocks and the fossil record edited by Philip Donoghue and M. Paul Smith, CRC Press, $109.95, ISBN 0415275245