Sir William Dawson (1820–1899): a very modern paleobotanist

Sir William Dawson was one of Canada’s most influential Nineteenth Century geologists. Although a lifelong opponent of the concept of evolution, a stance that resulted in him being sidelined by the scientific community, he made enormous contributions to Pennsylvanian paleobotany, especially at the Joggins fossil cliffs of Nova Scotia. Key to Dawson’s success was his recognition of the importance of a field-based research program, in which fossil plants could be observed in their precise geological context over a sustained period of time. Uniquely trained as both geologist and botanist, he was skilled in the microscopic analysis of permineralized plant anatomy, and appreciated the enormous potential of fossil charcoal as an untapped source of systematic information. Arguably his most extraordinary insights came in the field of plant taphonomy, in which studies of modern sedimentary processes and environments were used to interpret the rock record. His analysis of fossil plants in their sedimentary context allowed Pennsylvanian coal swamp communities, dominated by lycopsids and calamiteans, to be distinguished from the coniferopsid forests, which occupied mountainous regions further inland. The lasting significance of Dawson’s paleobotanical work is emphasized by many recent papers concerning the Pennsylvanian coal measures of Atlantic Canada, which have either directly built on research topics that Dawson initiated, or have confirmed hypotheses that Dawson framed. Until recent times, the discipline of paleobotany has been dominated by systematic fossil plant description with little or no reference to geological context. By virtue of his distinctively holistic approach, synthesizing all available geological and botanical data, Dawson is marked out from his contemporaries. His methodology does not appear old-fashioned even today, and it is therefore with justification that we describe him as a very modern paleobotanist. Resume Sir William Dawson a ete l’un des geologues les plus influents du 19e siecle au Canada. Meme s’il s’est oppose toute sa vie au concept de l’evolution, une position qui a amene le milieu scientifique a l’ignorer, il a enormement contribue a la paleobotanique pennsylvanienne, specialement dans les falaises fossiliferes de Joggins de la Nouvelle-Ecosse. La cle du succes de Dawson reside dans le fait qu’il avait reconnu l’importance d’un programme de recherche sur le terrain prevoyant l’observation des plantes fossiles dans leur milieu geologique particulier pendant une periode de temps prolongee. Grâce a sa formation unique de geologue et de botaniste, il possedait la competence voulue pour realiser une analyse microscopique de l’anatomie des plantes permineralisees et il comprenait le potentiel enorme du charbon de bois fossile comme source inexploitee de donnees systematiques. On pourrait soutenir que ses idees les plus extraordinaires se sont manifestees dans le domaine de la taphonomie vegetale, dans lequel des etudes d’environnements et de processus sedimentaires modernes ont servi a interpreter des antecedents lithologiques. Ses analyses de plantes fossiles dans leur contexte sedimentaire ont permis de distinguer les communautes des marecages houillers pennsylvaniens, dans lesquels predominent les lycopsides et les calamites, des forets coniferopsides, qui occupaient les regions montagneuses plus a l’interieur des terres. De nombreuses communications recentes au sujet des couches houilleres pennsylvaniennes des provinces de l’Atlantique, qui s’appuient directement sur des sujets de recherches amorcees par Dawson ou ayant confirme des hypotheses formulees par Dawson, mettent en relief l’importance durable des travaux paleobotaniques de Dawson. La discipline de la paleobotanique a jusqu’a tout recemment ete dominee par des descriptions systematiques de plantes fossiles evoquant a peine ou n’evoquant pas du tout le contexte geologique. Dawson s’est demarque de ses contemporains au moyen de son approche nettement holistique en realisant une synthese de toutes les donnees geologiques et botaniques accessibles. Sa methode de travail ne semble pas retrograde, meme aujourd’hui, et il est par consequent tout a fait justifie que nous le decrivions en tant que paleobotaniste tres moderne.