Dyke, G.J.

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7 Johnson, D.D.P. et al. (2002) Environmental correlates of badger socialspacing across Europe. J. Biogeogr. 29, 411–4258 Kruuk, H. (1978) Foraging and spatial organisation of the EuropeanBadger Meles meles L. Behav. Ecol. Sociobiol. 4, 75–899 Waser, P.M. (1981) Sociality or territorial defence? The influence ofresource renewal. Behav. Ecol. Sociobiol. 8, 231–23710 Buckley, N.J. and Ruxton, G.D. (2003) The resource dispersionhypothesis and the ‘future value’ of food. Trends Ecol. Evol. 18, doi:10.1016/S0169-5347(03)00154-X0169-5347/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved.doi:10.1016/S0169-5347(03)00155-1|Book ReviewsCounting the pages of books about dinosaurs andbirdsMesozoic Birds: Above the Heads of Dinosaurs edited by Luis M. Chiappe and Lawrence M. Witmer. University of California Press,2002 £66 hbk (532 pages) ISBN 0 520 20094 2Dinosaurs of the Air by Gregory S. Paul. The Johns Hopkins University Press, 2002. US$49.95 hbk (460 pages) ISBN 0 8018 6763 0Gareth J. DykeDepartment of Zoology, University College Dublin, Belfield Dublin 4, IrelandThe past few years have been an amaz-ing time for students of bird origins –exceptional new feathered and nonfeath-ered theropod dinosaurs, birds such asRahonavis that don’t look like birds [1],theropods, such as alvarezsaurs and thefour-winged Microraptor, that do look likebirds [2,3], even fake birds (‘Archaeorap-tor’) that aren’t even birds at all [4], havebeen discovered and described at analarming pace. Because the number ofnew species of Mesozoic birds discoveredand described over the past ten yearsmorethan triples those knownformuchofthe past two centuries, keeping up withthe recent literature in this area can bemore than a little confusing. It is helpfulthen to sometimes consult books, and you could do worsethan to read these two recent offerings.Although essentially dealing with the same subjectmatter – the early fossil record of birds and theirdinosaurian relatives – Mesozoic Birds: Above the Headsof Dinosaurs and Dinosaurs of the Air couldn’t be moredifferent. In the first of these two volumes, Chiappe andWitmer have assembled a sequence of authored papers(many addressing topics of interest for the first time)that deal with specific subjects tied together within thegeneral arena of Mesozoic avian evolution. This book isprimarily a collection of research contributionswhereas Paul’s thesis in Dinosaurs of the Air is topresent a summary of the dinosaur and bird fossilrecord and to interpret it in light of his own ideasregarding the origin and evolution of flight. The firstbook then is less suitable for a general readership andthe latter is eminently so; both fill a niche and havebeen long anticipated by the scientific community.One great advantage of Mesozoic Birds is that itpresents a status report of an active field of enquiry.Several chapters present detailed descriptions of taxahitherto known only from short initial reports in theprimary literature (Shuvuuia and Vorona), or summarizeanatomical information pertaining to tantalizingly incom-plete but informative fossils (Avimimus and Alvarez-saurus). Fossil material discussed in this book is verywell presented, both adequately described and evaluatedin context with the use of convincing character analyses.Descriptive chapters are augmented with contributionspresenting ‘state-of-the-game’ systematic analyses fornon-avian theropods (Clark et al.) and basal birds(Chiappe) that bring readers up-to-speed with the currentconsensus. The editors of Mesozoic Birds, Chiappe andWitmer, have certainly achieved their goal – to synthesizethis diverse field of study (comprising topics such as theorigin of birds and the evolution of their flight with thetaxonomy of Archaeopteryx and reviews of feathers,histology and tracks) without appearing clumsy (andmore importantly, out-of-date). As is the case with manyedited amalgamations of co-authored papers, MesozoicBirds was long in the pipeline, a fact that is happily notreflected by the bulk of its chapters.By contrast, and departing somewhat from currentconsensus, Paul’s lavishly illustrated Dinosaurs of the Airis a work of art, albeit hanging by a thread of science.Readers will be left in no doubt about the artistic ability ofthe author and, indeed, about his ability to summarizeeffectively literature pertaining to the origin of birds in aconcise and engaging manner. I would certainly rec-ommend Dinosaurs of the Air to anyone entering thefield for the first time – it is exceptionally well illustratedand provides a great introduction to the major fossil groupsof dinosaurs and birds. Enough said? No, because there is athread inherent to Dinosaurs of the Air that comes to thefore in later chapters – Paul has an agenda with this book.Following the opening (and very informative) descriptiveand anatomical chapters, Paul draws us into his ideasabout the evolution of flightlessness; in short, thehypothesis that many familiar groups of dinosaurs(troodontids and oviraptorosaurs among them) do notCorresponding author: Gareth J. Dyke (gareth.dyke@ucd.ie).Update TRENDS in Ecology and Evolution Vol.18 No.8 August 2003382http://tree.trends.comcomprise the sister groups of birds. His argument is thatmany of these taxa are actually birds that, for somereason, lost the ability to fly. Although he does notdeny a close relationship between non-avian dinosaursand birds, as the reader of Mesozoic Birds will realize,Paul turns the accepted shape of parts of thedinosaur–bird tree on its head. The jury is still outon this issue and, as such, this interesting idea shouldbe taken with a pinch of salt. This book is, never-theless, among the finest dinosaur books out there – itcertainly belongs on the shelf of everyone with aninterest in this area (even if your fascination is simplywith fine dinosaur art).My interest is sparked; both books make excellentreading and will no doubt form integral parts of the‘dinosaur research library’ for many years to come.References1 Forster, C.A. et al. (1998) The theropodan ancestry of birds: new evidencefrom the Late Cretaceous of Madagascar. Science 279, 1915–19192 Chiappe, L.M. et al. (1998) The skull of a new relative of the stem-groupbird Mononykus. Nature 392, 272–2783 Xu, X. et al. (2003) Four-winged dinosaurs from China. Nature 421,335–3404 Zhou, Z. et al. (2002) Archaeoraptor’s better half. Nature 420, 2850169-5347/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved.doi:10.1016/S0169-5347(03)00131-9Physics of movement on land, sea and airPrinciples of Animal Locomotion by R. McNeill Alexander. Princeton University Press, 2003. £35.00, hbk (376 pages)ISBN 0 691 08678 8C.J. PennycuickSchool of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UKIn his latest book, Alexander examinesthe way in which the infinite variety ofadaptations to walking, swimming andflying are shaped and constrained byNewtonian mechanics. Energy (kineticand potential) is at the centre of thediscussion, together with the storageand retrieval of energy in elastic struc-tures and fuel reserves. From almost thefirst page, Alexander slips frequently into a mathematicalidiom to illustrate what some ‘ideal’ animal would andwould not be able to do, given simplified physicalconstraints. This is an immensely powerful approach forthose who are used to reading an equation slowly, andthinking over its implications symbol by symbol. Sadly, notmany biologists will do that, but those who persevere willbe well rewarded. Principles of Animal Locomotion coversthose animals that use muscles as the source of work forlocomotion, and begins with an explanation of the slidingfilament mechanism, and the mechanical implications ofvarious types of muscle geometry. The need for mitochon-dria in aerobic muscles is mentioned, but (oddly) not theireffect on the mechanical power output of these muscles.Throughout the book, the supporting physiology is lesssharply focused than the mechanics of locomotion, perhapsbecause there is not much theory behind it.Alexander is at his best with the intricacies of walking,running, jumping, hopping, burrowing, wriggling andclimbing, modes of terrestrial locomotion that arthropods,reptiles, mammals (and Alexander) have made their own.His basic approach is to set an upper limit to the powerthat the animal requires, by calculating the work thatmust be done at each step or stride to generate kinetic andpotential energy, and to overcome resistance in the outsidemedium. He then considers the numerous ways in whichthe average power can be reduced, by storing energy inelastic structures, and recovering it in a later cycle.Although the amount of this energy recovery has beenmeasured in some cases, there is unfortunately no generalway to take account of it. Generalizations about power aretherefore quite limited, usually taking the form ofpredicting allometric trends for upper limits. Alexanderis most authoritative on his home ground of mechanics, buttends to believe what he reads when he ventures intophysiological territory. He makes especially effectiveuse of the Froude number, combining the size of ananimal with its speed and the strength of gravity, as aunifying principle in terrestrial locomotion, but fails tonotice that ‘cost of transport’ is another such unifyingdimensionless number, at least if one takes thephysiological term ‘weight’ to have the same meaningas in physics.Alexander analyses the mechanics of animals thatrun on the water surface, and those that swim downbelow by undulation, oars, hydrofoils, and jets. He isespecially good on buoyancy, a topic to which hehimself made notable contributions in his youngerdays. Taking to the air, he divides the flight of insects,birds and bats into gliding, hovering and poweredforward flight, and hopes to avoid controversy by citingeverybody, contradictions and all. He knows that birdsexhibit none of the features so carefully explained inhis own Chapter 7 about the gaits of mammals, yet heis puzzled that nobody has measured the speeds atwhich birds ‘shift’ between one nonexistent gait andanother. The mathematical approach loses focus whenit comes to reviewing the heterogeneous mass ofmaterial about flight, where some authors drawCorresponding author: C.J. Pennycuick (c.pennycuick@bristol.ac.uk).Update TRENDS in Ecology and Evolution Vol.18 No.8 August 2003 383http://tree.trends.com

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