585 _N_A_T_u _R_E_v_o_L_. _33_s_1_3_o_c_T_o_s_E_R_1_98_x______NEWS ANO VI EWS------Taxonoiny blooded by cladistic wars

Palaeontologists have buried the hatchet of cladism, to the general enlightenment. But the siege mentality at a meeting last month argues for the preservation of comparative anatomy.

AFTFR decades of study of long-dead been much soul-searching among the clad­ Vietnam (Philippe Janvier, Paris) and animals, vertebrate palaeontology in ists, but the whole of systematics has a Bolivia (Pierre Gagnier, Paris). The Britain itself now faces extinction, and the surer foundation as a result. Ordovician ostracoderm Sacabambaspis situation elsewhere in Europe is not much There is room for numerical taxonomy janvieri may hold the clues to the nostril better. It is ironical that the lives of pre­ in the new liberalism, as when Garth structure of heterostracan ostracoderms historic animals arc avidly followed in the Underwood (formerly at the City of (a long-standing mystay) and also illumi­ public prints, but that the academic disci­ London Polytechnic) used compatibility nate early vertebrate radiation. plines from which the scripts of these soap analysis to reveal parallelism in the tooth Inevitably. the periodic mass-extinction operas spring are being starved. Worse structure of snakes. The view that venom­ hypothesis of David Raup and Jack still, comparative anatomy, without which injecting fangs are the 'crowning glory' of Sepkoski is grist to the mill of the new vertebrate palaeontologists would be snake evolution seems to be more reveal­ taxonomy. Colin Patterson and Andrew hardly better equipped to trace the history ing of people's fear of snakes than of Smith (BMNH) continue to complain that of life than stamp collectors, may be drag­ sound taxonomic judgment. the taxonomic data on which the hypothe­ ged down as well. Changes of perspective have also sis rests arc flawed. They say that in Comparative anatomy does not evoke a helped with the ordering of sea snakes Sepkoski's data, drawn from his own natural fondness among most working (Colin McCarthy, BMNH) and modern compendium of the stratigraphic ranges of biologists. To many, the smell of formalin rock-dwelling lizards (Nick Arnold, marine fossil families and later genera, the means mustiness more generally. Yet to BMNH). Each of the 30 or so indepen­ naming of fossil species owes more to the work on a living organism without sound dently evolved groups of the latter has a circumstances of collecting than biological knowledge of what it is, and how it is put parallel solution for life in a difficult envi­ reality. For example, 68.8 per cent of all together, diminishes the worth of what ronment. But the solutions are substan­ fossil fish species are known from unique results emerge. The tale of the embryo­ tially determined by ancestry so that, by localities. The figure for echinoderms is logist whose observations of a batch of sea contrasting environment and ancestry. 69.1 per cent. But the ecology of fish and urchin embryos were thought anomalous rock-dwelling lizards can be a test for the echinoderms are very different. so that the until it was realized that the species used extent of convergent evolution. figures are too close to be coincidental, was itself unusual is not apocryphal. By mixing comparative anatomy with which implies that the formal taxonomy of Even so, the plight of comparative palaeontology, Jennifer Clack (Cam­ all marine species is based on locality, not anatomy is at least partly self-induced. bridge) produced at Boulogne a new biology. And the same may be true for The emergence in the 1980s of cladistics, answer to the old question of how the other groups of marine animals. in principle an objective method of build­ earliest land animals could hear. New Patterson and Smith also say that the ing phylogenies from structural similarity specimens of Acanthostega, an early ·noise' in Raup and Sepkoski's mass­ between forms, provoked arguments tetrapod from the Devonian of Green­ extinction ·signal' from marine families between the newcomers and the tradi­ land, show that while the animal had a and genera arises from misapplied taxo­ tionalists unusual for their savagery. The stapes, that was too big and well-ossified nomy, as when groups treated as mono­ result was to corrode the climate in a small to have fitted into the otic notch at the phyletic turned out to be polyphylctic or community of researchers and to invite back of the skull, traditionally regarded as paraphyletic. Even at the species level, outsiders to regard these unseemly wran­ the rim of a tympanic membrane. Neither taxonomy has been misapplied to produce gles as signs of a subject in terminal crisis. did the stapes provide support for the names of little more than administrative That is why it matters that the Cladistic braincase. Instead, it may have controlled significance. If this raking over old coals Wars are now over. So much was plain at ventilation through a spiracle, much as the sounds like the cladistic wars at their the 36th Symposium of Vertebrate Palae­ hyomandibular (the stapedial homologue) height , there is a side-benefit: there is a a ontology and Comparative Anatomy, at does in some fishes. An air pocket in the much better idea of the phylogeny of fish Boulogne last month. Within a single spiracular cavity would have, incidentally, and echinoderm genera than before Pat­ decade, attitudes towards clad is tic been an excellent resonating chamber. terson and Smith's analysis. methods have swung from abhorrence to That is another feather in the cap of com­ But while adversity has removed the acceptance; serious taxonomy based on parative anatomy. luxury of internecine strife, a siege men­ old subjective ways is now almost unthink­ Comparative anatomy has also been tality has palpably taken over. Palaeonto­ able. But even cladistic purists now brought to bear on the question of verte­ logists know they have a fustian image acknowledge the value of fossils in the brate origins by Richard Jefferies and among other biologists, but the archaic resolution of three-taxon problems. Tony Cripps (BMNH), who demonstra­ monographs cited in their papers are a Thus Peter Forey (British Museum, ted how vertebrates may have evolved doleful reminder that comparative ana­ Natural History, otherwise BMNH) , once from echinoderm-like animals called cal­ tomy has too often been abandoned for a cladistic hawk, used fossils of the primi­ cichordates. Their approach differs from less well-founded disciplines, palaeoeco­ tive lobe-finned fish Diabolepis to resolve Garstang's 'auricularia' theory of the logy for example. Yet it is not much a coelacanth-lungfish-tetrapod tricho­ 1920s in that it is based on real fossils. comfort to know that a 1911 lungfish tomy. Coelacanths and lungfish are seen At Boulogne-sur-mer, French resear­ monograph may still be valid while much as sister groups, with tetrapods a sister chers appropriately led in the study of the work from the l 950s and 1960s will prove group to both. But the proposed sister­ earliest, fish-like vertebrates. The taxo­ of historical interest only: for if compara­ group relationship between lungfish and nomy of Alain Blieck (Lille) was the tive anatomy goes. the rest of biology will tetrapods is now less certain. There has backdrop for the exciting new faunas from suffer irreparably. Henry Gee