BOOK REVIEWS 331

seems, it would be a great pity not to pay homage to thegreat Charles Lapworth by visiting at least some of thesections described.

In effect, what you will have done in working your waythrough these itineraries is gained an insight into the LowerPalaeozoic, Upper Palaeozoic, Permo-Triassic, Tertiaryand, to a lesser degree, Quaternary history of southwestScotland, putting it together piece-by-piece, just like theold-time geologists. It should be said, however, that thePleistocene and Holocene get short-shrift, which I am surewill disappoint many geographers and other customers,especially as the region has so obviously been glaciated andsubject to considerable fluctuations in sea-level duringthose times. Funnily enough, Quaternary and coastalgeomorphological locations are given more prominence inthe list of 47 Sites of Special Scientific Importance, thesecond of two short appendices, the other dealing withmetalliferous mineralization. Both are useful adjuncts. So isthe comprehensive list of references, although one mightquibble about the insertion of unpublished PhD theses. Anamateur or teacher looking at the list might think 'whereshould I start with this lot? It might have been better to'star' certain publications as essential or highly desirablereading, on the additional basis that they were readilyavailable via geological society or public libraries. Perhapsmy biggest let-down in this otherwise excellent publicationwas the thought of seeing the Loch Ness Monsterapparently translated into Kirkcudbright Bay, only to find itwas an S-shaped outcrop of a Siluro-Devonian lamprophyredyke!

There is no question that this is a major contribution togeological education and a very fitting tribute to the lateByron Charles Linton, a person clearly highly regarded byhis colleagues in the British Geological Survey, andelsewhere.

TREVOR GREENSMITHGA Guides Editor

Prehistoric Life - The Rise of the Vertebrates, DavidNorman (illustrations by John Sibbick), 1994, Boxtree,London, 246 pp. ISBN 0-7522-1091-2 (PB) £14.99.

The author clearly knows his target audience for thisfascinating and beautifully illustrated book charting the riseof the vertebrates. There is barely a page without a photo­graph, illustration, diagram or box to make the clear,jargon-free text more accessible to the reader withoutspecialist knowledge. Dr Norman acknowledges the diffi­culties of condensing the history of life over some 3500million years into a few hundred pages and, as Director ofthe Sedgwick Museum and a lecturer in palaeontology andevolution at the University of Cambridge, he is also wellaware of the great leaps of faith required by non-specialistreaders because of the incomplete fossil record. He owns upto a little cheating in that he glosses over the early history

to about 500 million years ago, then charts in some detailthe evolution of backboned animals and, even morespecifically in later chapters, the land vertebrates. He iscareful to present a range of arguments over unproventheories so that the reader is kept very much up to date withcontroversies and a balance is maintained.

At the beginning of each of the ten chapters is aTimescale of Earth history which sets the geologicalcontext (but what a shame that on the very first one (p.24)Proterozoic Eon is mis-spelt as Protozeroic). Each chapteris broken down by section and sub-headings making the'story line' easy to follow and read. Chapter I highlights theorigin of the universe through the 'Big Bang' theory andthen moves quickly on to the structure of the Earth. Basicgeological concepts and measurement of geological timeare explained by simple analogies, so, for example, 'thefloor of the Atlantic is spreading apart at roughly the samerate at which your fingernails grow'. It continues with areview of fossils and fossilization, progressing naturally toa brief discussion of evolution with its current contro­versies. Chapter 2 dashes through the beginnings of lifetaking a highly simplified approach - the idea of pro­gression from the development of the earliest atmosphere tosimple chemicals to living organisms; from bacteria-likecells (prokaryotes) to the more complex eukaryotes andthence to multicellular organisms, a process which tooksomething of the order of 3000 million years. Dr Normancites endosymbiosis as the most convincing theory for theorigin of the eukaryotes, though does acknowledge that thisis not universally accepted and the fossil record for thisperiod is difficult to interpret.

Recent research seems to support the idea that 'theexplosion of life' seen in the fossil record at thePrecambrian-Cambrian boundary, about 550--530 millionyears ago, is a real phenomenon and the variety anddiversity of these marine organisms continued to rise untilthe mid-Ordovician. From then until the present, some 470million years, the level of diversity remained fairly constantbut species changed significantly. The illustrations of theweird and wonderful Ediacara and Burgess Shale faunafrom this explosion are superb and Dr Norman discusses insome detail the varying theories for their rise. One smallcriticism here, though, after spending half a page illus­trating and discussing the right way up for Halluciginia, itssilhouette on the following page is drawn upside down! (pp.46 & 47).The development of the chordates, of which oneof the three modem groups is the vertebrates, is traced fromthis time, though their origin is still in dispute. The fol­lowing two chapters(4&5)cover the Late Cambrian to thePermian Period, charting the rise and fall of marinecreatures, the development of land plants and the firstforays of animals on to land. Theories on the evolution ofbuoyancy, jaws, lungs and fin/limbs in these animals areexplained. Links between the Devonian lungfish and extantlungfish found today in Africa, South America andAustralia are discussed. The. palaeontological and fossilevidence for the evolution of legs from fins and for thetetrapod vertebrates gaining a foothold on the land is simply

332 BOOK REVIEWS

presented along with a number of differing theories/interpretations of how and why the changes might haveoccurred.

The story continues with the gradual diversification ofthe tetrapods in form and habitat to the evolution of thereptiles. The big change here was the laying of eggs (withprotective shells) on land as opposed to jelly-covered onesusually laid in water by the tetrapods. Reptile rise began inthe Mid- Carboniferous with small lizard-like creatures anddeveloped through the Permian to mammal-like reptiles,which then dominated much of the Permian and Triassic asthey continued to diversify through some 70 million years.The Mesozoic Era (245-66 million years ago) saw theemergence of the flying reptiles (pterosaurs), although thereis still considerable debate about their origins which theauthor presents succinctly. The skeletal changes whichoccurred in the some of the small, already bipedal, reptilesled to the appearance of the dinosaurs towards the end ofthe Mid-Triassic and the book explores these changes insome detail. Dr Norman then sets the geological contextfrom the Late Carboniferous to the Late Triassic, a timespan of some 100 million years. He suggests that thecreation of the supercontinent Pangea during this time, withits associated coastline and sea-level changes, had profoundevolutionary effects. The appearance of birds and dinosaursduring the Late Triassic, at the expense of the mammal-likereptiles, is considered in some detail and accompanied bywonderful illustrations. The reasons for the primacy of thedinosaurs during the 160 million years of the Mesozoic, atthe expense of the mammal-like reptiles and mammals, isstill the subject of debate, as is their extinction (and theextinction of many other species), and the competingtheories are well presented.

The Tertiary Period, of some 64 million years, withmajor environmental and geographical changes, saw ahuge rise in the variety and number of mammals and theiramazing adaptability is clearly illustrated. The mass extinc­tions at the end of the Cretaceous, combined with theTertiary changes, provided a rare opportunity for exploit­ation of vacated ecological niches, and, concentrating on

the mammals, Dr Norman describes their successes withenthusiasm and clarity.

The final chapter of the book (the Quaternary) brings intofocus the rise of the primates. The fossil record of the earlyprimates is patchy, and on scant evidence (single cheekteeth, for example) it has been claimed that the firstprimates appeared in the Late Cretaceous. Apart from fossilevidence, Dr Norman looks at the opportunities presentedby molecular biology in determining human origins. DNAand various protein analyses have indicated that thechimpanzee is closest to humans followed by the gorilla,the orang-utan and the gibbon. From this evidence it hasbeen suggested that humans diverged from chimpanzeesbetween 7 and 5 million years ago. The chapter then chartsthe rise of the hominids to modern humans, covering re­search of the past 40 years or so from East Africa. He skimsthrough some social anthropology at the end of the chapterand muses on the swift rise of humans and of human domin­ation of the Earth during the past 10 000 years - a mereblink on the geological time-scale. He leaves the reader tothink carefully about the effects that this rapid rise of thehuman population has had on the environment and mayhave on human evolution.

And at the end, has the author succeeded in setting theevolution of humans, as a species of land vertebrate, withinthe context of land vertebrate evolution? Has he raised ourawareness of our position in this hierarchy and helped usrecognize that we are not necessarily the most importantcreatures on this Earth? Has he persuaded us that we dohave a responsibility to protect our environment and notallow apathy and procrastination to detract us from thisrole? Can we still justify our species name - Homo sapiens?

Reading this book, it is clear that there is still amplescope for budding palaeontologists, amateur andprofessional, to pursue all manner of research. Thecomprehensive, if somewhat idiosyncratically annotated,reading list should provide an excellent starting point for'getting into' the subject.

SUSAN BROWNGA, London