Radiolarians in the geological record

AFANASIEVA MARINA; AMON EDUARD; AGARKOV YURI; BOLTOVSKOY DEMETRIO

Paleontological Journal

Nauka Interperiodica

Lugar: Moscu; Año: 2005 vol. 39 p. 135 - 391

0031-0301

This study is dedicated to the comprehensive description of radiolarians, the discussion of their morphology, problems of classification, and their important role in the history of the Earth’s biosphere. It contributes to the solution of the fundamental problems of the evolutionary morphology of radiolarians, related to the study of the morphogenesis of their skeletons at various structural levels through geological time, aiming at the creation of a morphological basis for the phylogeny and classification of the phylum Radiolaria. The book describes the 200-year history of radiolarian classification. The biology and morphology of radiolarians are discussed. The study deals with the successive stages of the ontogeny of radiolarians and the main patterns of skeletal morphogenesis: appearance and growth of skeletal elements, biomineralization, and secondary transformation of skeletons. A new classification of the phylum Radiolaria, uniting two superclasses Phaeodaria and Polycystina, is proposed. The superclass Polycystina is composed of six classes: Aculearia, Sphaerellaria, Spumellaria, Stauraxonaria, Nassellaria, and Collodaria. Patterns in the appearance/disappearance and distribution in time of higher taxa of Polycystina are discussed, and critical levels in the evolution of radiolarians at the major stages of the Phanerozoic are revealed. Four phases and nine stages in the evolution of radiolarians are recognized. Problems of the biology, ecology, and taphonomy of radiolarians are discussed. It is shown that the biomass of polycystine radiolarians is greatest at depths of 50–400 m. The conclusion is made that radiolarians cannot be regarded as indicators of exclusively oceanic deep-water conditions. In the geological past, the maximum density and diversity of the population of radiolarians was observed in the coastal regions or zones of aulacogens and active tectonic faults. Statistical analysis of the biodiversity of radiolarians in the Phanerozoic is conducted based on the informational system RADBASE containing information on 1722 genera of radiolarians and their synonyms. The study is expected to be of use to a broad range of readers in paleontology, biostratigraphy, paleoecology, and as a textbook for the university courses. It contains 67 figures, 11 tables, 33 plates, and an appendix. The list of references includes 461 names.