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The Structure, Development and Evolution of Reptiles

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The Structure, Development and Evolution of Reptiles 41 HERPETOLOGICAL .JOURNAL. Vol. I. pp. 41--14 ( 19Xf1) REVIEW: THE STRUCTURE, DEVELOPMENT AND EVOLUTION OF REPTILES Symposium o(thc Zoological Sociei.1· of'Lo11do11 No. 52. Co-sponsored hr till' British 1-frtpl'tologirnl Sncictr PROFESSOR ANGUS n'ALBINI HFl.LAIRS Fcstschrifi Volume. Academic Press. l.011do11. 198./. ARMAND J. DE RICQI.i:s U11ivcrsi1e Paris VII. ] Place ./11ssic11. 75005 Paris. France. This thick volume, hardbound under an elegant blue The next paper, by E. N. Arnold (London, England) cover with gold lettering, is offered under the usual deals with characters of cloaca! and hemipenial good publishing standards expected from Academic musculature among lizards. This paper show beautifully Press. Even though my own copy had no cover jacket how the careful comparative study of a complex and perhaps suffered from some very minor over system can produce important data for the study of inking, making some drawings and photographic relationships. This paper also offers an admirable plates a little bit too dark, the overall publishing and example of a soft, diplomatic, "cryptoclaclism". While printing quality is, by and large, excellent. the methodology of inferring relationships.is definitely After the usual general introductory materials, the pervaded by a cladistic approach, the paper is Introduction chapter itself, by the Editor, Professor M. "careful" not to offer even one cladogram and rather Ferguson (Manchester) is a lively and informative forcefully concentrates on good empirical data sketch of Professor d' A. Bellair's career, with many gathering.and descriptions. humorous and thought-provoking hints on academic Next comes a paper by P. C. H. Pritchard (Maitland, life, past and present. The main content of the book is Florida, USA) on piscivery of turtles and evolution of formed by no less than 27 specialised papers, most of long-necked Chelidae. This work offers an interesting them single-authored. They are arranged under five methological contrast with the preceding one. general themes, forming large chapters or sections, The Squamate epidermis, as explained in the next which are successively: Morphology (six papers), paper by P. F. A. Maderson (New York, USA) appears Development (six), Physiological Ecology (seven) and to be an excellent model system for the study of Evolution (seven). This provides a sensible framework epithelial tissue homeostasis. This most stimulating within which the diversity of the papers could be paper, in fact, brings together many cytological, arrayed, although several papers could easily have developmental, physiological and natural history data been shifted, on logical grounds and content, from one into mutual interaction, to propose a new synthetic section to another. Such a situation is, to this reviewer, view of squamate skin biology. very diagnostic of the current state of the art and trends The next paper, by Presley (Cardiff, Wales) on the R. in Vertebrates Evolutionary Biology, and more will be problems of tympanic membrane homology closes the said on that later. section on morphology. Here, Presley offers us, from Because it would not be realistic to try to review the point of view of descriptive embryology, a truly uniformly all and every paper in the book, no admirable piece of work where careful divisions apologies are due for a more in-depth analysis of some between "Epistemological", historical, descriptive and papers than of others, depending on the reviewer's interpretative sections allows the reader to find its way interests and expertise. This admittedly subjective between Charybde's an!agen and Scylla's controversies. analytical treatment will be balanced, to some extent, More generally, thanks to w<;>rks such as this one, it by overall synthetic comments on the book as a whole is perfectly clear how and why the good tradition of at the end of the review. descriptive, detailed, developmental embroyology Study of the 'Slide-pushing' locomotion, recognised should be kept alive and healthy within modern by Carl Gans (Ann Arbor, USA) as a new locomotory evolutionary Biology. Indeed, how could we do process among elongate Squamates, opens the section without it? Wouldn't it be a good thing for the on morphology. This paper is a clear, concise addition Universities to keep this beautiful field of knowledge to our knowledge of limbless locomotion. and research alive, even if it is contemptuously labelled The study of anterior limb skeleton and musculature a "traditional" one by some potent ignorants? in in relation to sprawling gait, by M. F. Section Two, on development, opens with a paper Varanus J. Landsmeer (Leiden, The Netherlands) is an excellent by B. Hall (Halifax, Canada) on developmental K. example of the usefulness and relevance of good processes underlying the evolution of cartilage and "classical" anatomy for functional and evolutionary bone. morphology, a fact perhaps too often forgotten in The richness of his contribution precludes detailed more "fashionable" (i.e. electromicrographic) approaches. analysis and comments; it de<ds especially with the 42 ARMAND J. DE RICQLES problems of secondary cartilages, metaplastic bone Obviously, much further work of considerable and (secondary) epiphyseal centres among reptiles. Ifl interest is likely to follow. fu lly agree on the all-important issue of timing shifts of The last paper in the section on development is a developmental processes as a key mechanism in rather short review by K. W. Jones (Edinburgh, skeletal evolution, I am not fully convinced by the Scotland) of the problem of evolution of sex author's contention that reptiles lack secondary chromosomes in reptiles and mammals, with emphasis cartilages (they appear to be "already" ·developed on snakes. The paper mainly introduces a model which among some osseous fishes) and that "reptilian. would account, in evolutionary terms, for the diversity periostea have limited osteogenic ability". of mechanisms of sex determination within groups, The next two contributions, one by K. Murreoka and fromone group to another. I have the feeling that and S. Bryant (Irvine, USA) on regeneration and the literature coverage, especially regarding the development of vertebrate appendages on the one problems of environmental sex determinism among hand, and the one on pattern formation during reptiles, is rather on the light side. development of amniote limbs by L. S. Honig (Los The next section, dealing with physiological Angeles, USA), on the other; can be treated together. ecology, starts with an interesting work of G. J. Webb Both papers deal with experimental embryology of (Kensington, Australia) and A. M. Smith (Canberra, vertebrate limbs, the first paper focussing mainly on Australia) on sex ratios and survivorship in the amphibians, the second one on amniotes, including Australian freshwater Crocodilus johnstoni. some reptiles. Elegant experimental approaches, The study seems to me a model of careful naturalist combined with new conceptual frameworks, have both work spanning from extensive field surveys to contributed significantly to the recent advances in this theoretical computations, via histological gonad fascinating field. But how do cells appear to "know" analysis. It is clear, however, that the "advantages" (if what they "have to do" at the "right" time and places? any), in terms of classical selective/evolutionary This all-important issue of developmental biology is theories of "epigenetical" sex determinism, still seem far from settled, as evidenced by these lucid and up to far from being clearly understood. date papers. How relevant and useful the limb V. Lance's (New Orleans, USA) paper on development regeneration models are to address the endocrinology of reproduction in male reptiles seems issue meaningfully is also made quite obvious here. to me to be a clear, up to date, synthesis review of an Professor M. Fergusson's paper on craniofacial interesting problem, much more orientated, however, development in Alligators is the next contribution. towards histo-endocrinology than towards physio­ This big paper summarises nearly 10 years of work and logical ecology itself. My only reservation is that, the author's PhD Thesis. Starting with problems of perhaps, not enough emphasis is put on the cleft palate malformations among mammals (a relationships between reproducive cycles and the problem with obvious medical and social importance), various environmental ones, such as climatic cycles, he went onto realise that the crocodilian secondary that male reptiles find in their actual environments. palate could be used as a most satisfactory model to The next paper, by H. R. Bustard (Alyth, Scotland) understand normal and pathological palate morpho­ reviews the captive breeding behavjour of the gharial. genesis. This, in turn, led to an intensive research This is part of a major UN and Government of India project on crocodile development and growth, in order conservancy project, the aim of which is to save the to fully master the model's characteristics. These Ganges gharial from extinction. This lively report is a efforts have been successful enough to push the true piece of natural history, full of practical crocodilians froma position of poorly-known reptiles, experiences, political, managerial and ethological. It as far as development was concerned, to the status of a happily ends with reasonably optimistic prospects for well standardised, operational model for modern gharial survival. development biology, a not inconsiderable achieve­ Thermoregulation,
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