Radiolaria

Radiolaria are a very diverse marine siliceous microplankton group that have existed at least snice the Cambrian to the recent. This volume gives a representative view of research topics discussed at the 10th International Meeting of Radiolarian Palaeontologists. The articles of this volume cover mainly radiolarian biochronology and radiolarian fauna changes.

This comprehensive synthesis of our knowledge of the biostratigraphy of marine plankton is the work of an international team of eighteen authors. It covers all the major fossil groups that can be used to date sediments and rocks in the time interval Late Mesozoic to Holocene. Altogether more than 3200 taxa are considered, almost all of which are illustrated and depicted on range charts, making the book a valuable work of reference in the earth sciences. For ease of reference by specialists interested in either calcareous or non-calcareous microfossils, the original work is now divided into two independent volumes. Volume 2 describes siliceous and other non-calcareous microfossils, covering radiolaria, diatoms, silicoflagellates, dinoflagellates and ichthyoliths.

The study of marine plankton has traditionally focused on those or ganisms that appeared to have obvious ecological significance in un derstanding the major patterns of biological productivity, trophic relations, community structure, and the dynamic interaction of living things with the physical environment. Not infrequently, this thrust has centered on the apparently most abundant and/or larger members of the plankton community, including significant primary producers such as the diatoms, nonthecate algae, and flagellates, or the major con sumers--copepods, gelatinous metazoa, and other abundant metazoan invertebrates. Consequently, some of the less well recognized but also abundant microzooplankton have been given less attention. The radio laria, although widely studied as fossils by micropaleontologists, have in modem times. This is la been relatively neglected by biologists mentable given their widespread distribution in the oceans, remarkably complex form, and not infrequently localized abundance. Their diver sity of form, encompassing solitary species of microscopic dimensions and colonial species as large as several centimeters or more, challenges us to explain their evolutionary origins, explore their structural-func tional correlates, and comprehend the ecological basis for their wide spread occurrence in all oceans of the world fromihe greatest depth to the surface of the sea. Their intricate and aesthetically pleasing skeletons of enormous variety and fine-detailed design formed from amorphous silica (opaline glass) offer a unique biomineralized product that defies immediate biological explanation.

Polycystine radiolaria are exclusively marine protists and are found in all ocean waters, from polar regions to the tropics, and at all water depths. There are approximately 600 distinct described living species and several thousand fossil species of polycystines. Radiolarians in general, and polycystines in particular, have recently been shown to be a major component of the living plankton and important to the oceanic carbon cycle. As fossils radiolarians are also fairly common, and often occur in sediments where other types of fossils are absent. This has made them very valuable for certain types of geologic research, particularly estimating the geologic age of the sediments containing them, and as guides to past oceanic water conditions. As our current understanding of the biology, and even taxonomy of the living fauna is still very incomplete, evolutionary studies based on living polycystines are still rare. However, the common occurrence of numerous specimens for many species, and in a wide variety of oceanic environments, provides an excellent opportunity to study the processes of biologic evolution in the fossil record. Paleobiology of the Polycystine Radiolaria is the first major book on radiolarians to appear in the western literature since 2001. Focusing on living and fossil siliceous shelled radiolarians, it is notable for its emphasis not upon morphologic or taxonomic detail but on concepts and applications. The book attempts to provide a balanced, critical review of what is known of the biology, ecology, and fossil record of the group, as well as their use in evolutionary, biostratigraphic and paleoceanographic research. Full chapters on the history of study, and molecular biology, are the first ever in book form. Written for an audience of advanced undergraduate to doctoral students, as well as for a broad range of professionals in the biological and Earth sciences, Paleobiology of the Polycystine Radiolaria summarizes current understanding of the marine planktonic protist group polycystine radiolaria, both in living and fossil form.

ÊThe significance of the Radiolaria in regard to the relations of life in the ocean has been increased in a most unexpected manner by the discoveries of the Challenger. Large swarms of these delicate Rhizopoda were found not only at the surface of the open ocean but also in its different bathymetrical zones. Thousands of new species make up the wonderful Radiolarian ooze, which covers large areas of the deep-sea bed, and was brought up from abysses of from 2000 to 4000 fathoms by the sounding machine of the Challenger. They open a new world to morphological investigation. When ten years ago (in the autumn of 1876) I accepted the enticing invitation of Sir Wyville Thomson to undertake the investigation of these microscopic creatures, I hoped to be able to accomplish the task with some degree of completeness within a period of from three to five years, but the further my investigations proceeded the more immeasurable seemed the range of forms, like the boundless firmament of stars. I soon found myself compelled to decide between making a detailed study of a selection of special forms or giving as complete a survey as possible of the varied forms of the whole class; and I decided upon the latter course, having regard both to the general plan of the Challenger Reports, and to the interests of our acquaintance with the class as a whole. I must, however, confess at the close of my work that my original intention is far from having been fulfilled. The extraordinary extent and varied difficulties of the undertaking must excuse the many deficiencies. The special examination of the Challenger collection was for the most part completed in the summer of 1881; I collected its results in my Entwurf eines Radiolarien-Systems auf Grund von Studien der Challenger-Radiolarien (Jenaische Zeitschr. f. Naturw., Bd. xv., 1881). Since the manuscript of this preliminary communication was completed only a few days before my departure for Ceylon, and since I was unable to correct the proofs myself, several errors have crept into the Prodromus Systematis Radiolarium included in it. These have been corrected in the following more extensive working out of it. Even at that time I had distinguished 630 genera and more than 2000 species; but on the revision of these, which I undertook immediately on my return from India, this number was considerably increased. The total number of forms here described amounts to 739 genera and 4318 species; of these 3508 are new, as against 810 previously described. In spite of this large number, however, and in spite of the astonishing variety of the new and marvellous forms, the riches of the Challenger collection are by no means exhausted. A careful and patient worker who would devote a second decade to the work, would probably increase the number of new forms (especially of the smaller ones) by more than a thousand; but for a really complete examination, the lifetime of one man would not suffice.

Radiolarians in the Sedimentary Record presents the current state of knowledge on fossil radiolarians. The author discusses the record, as well as new integrated taxonomic systems at the family level. The book provides comprehensive coverage of the fossil record of these unicellular organisms. It also discusses their important role in the history of the Earth and their development of the biosphere. This text will prove indispensable for graduate students and researchers in geology, oceanography and earth sciences.