An Introduction to Paleobotany

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AN INTRODUCTION TO PALEOBOTANY By CHESTER A. ARNOLD. PREFACE: The preparation of this book was motivated by a longfelt need for a concise yet fairly comprehensive textbook of paleobotahy for use in American colleges and universities. Although se jftrate courses in paleobotany are not offered in many institutionsfifr ssil plants are fre quently treated in regular courses in botany and aleontology. In these courses both student and instructor are often compelled to resort to widely scattered publications, which are not always conveniently avail able. Lack of ready access to sources of information has retarded instruction in paleobotany and has lessened the number of students specializing in this field. Another effect no less serious hag bteen the frequent lack of appreciation by botanists and paleontologists yf the importance of fossil plants in biological and geological science. The two works of reference principally used by British and American students of paleobotany within recent decades have been Sewards Fossil Plants and Scotts Studies in Fossil Botany the former con sisting of four volumes, published - at intervals between 1898 and 191 7, and the latter of two volumes, the last edition of which appeared in 1920 and 1923. Both are now put of print, and although they will continue to occupy a prominent place among the great works in paleobotany, they are already in many respects obsolete. Since the publication of the last edition of Scotts Studies, many new and important discoveries have been made, which have not only added greatly to our knowledge of fossil plants but which have altered our interpretations of some of them. Many of the newer contributions have resulted from techniques scarcely known to the writers of the first quarter of the present century. Thfese new techniques have also brought about certain shifts of emphasis, which are evident when one compares certain portions of this book with the writings of 30 years ago. The arrangement and scope of the subject matter is in part the result of 17 years of experience in teaching a small course in paleobotany open to advanced undergraduate and graduate students, most of whom were majors or minors in botany or biology. The approach to the subject is therefore essentially botanical. Paleobotany as a subdivision of paleon tology can be treated either biologically or geologically, but the two approaches are so different that to tiy to combine them would result only in confusion and lack of clarity. The present arrangement, therefore, is followed partly because of the necessity of making a choice, but mostly because of the authors conviction that it is best for instructional purposes. The author is not unaware of the preoccupation with paleo botany of many geologists who might with good reason prefer a presenta tion following the geologic time scale. Their requirements are met to some extent by the inclusion of the chapter on The Sequence of the Plant World in Geologic Time, in which an effort is made to summarize the floras of the eras and periods. Then, in dealing with some of the plant groups, the most ancient members are described first, thereby giving some idea of the major steps in development from their first appearance down to the present. In making selections of subject matter an author can hardly avoid being partial to his particular interests to the neglect of other material. In spite of an effort to avoid bias, the ready admission is made that this book is not free from it...