The Early Evolution of Metazoa and the Significance of Problematic Taxa

One of the great enigmas of evolutionary biology has been how to treat animals of problematic systematic position. Many are known only as fossils, so this area has been of particular interest to palaeobiologists. This book represents a wide synthesis. It embraces not only general problems of animal classification of animals and new information on their molecular sequences that bear on their wider relationships, but also addresses more specific problems. These include details appraisals of both living and fossil groups. From the fossil record special emphasis is laid on examples from exceptionally preserved biotas that include the Burgess shale-type faunas of the Cambrian of south China and western North America, the Carboniferous Mazon Creek beds of Illinois, and the Jurassic Osteno beds of northern Italy. In addition, experimental studies of soft-patrt preservation in jellyfish are relevant to comparable preservation in the fossil record.

1. Origin of metazoans: a phylogeny deducted from sequences of the 28S ribosomal RNA R. Christen, A. Ratto, A. Baroin, R. Persasso, K. Grell and A. Adoutte; 2. Major factors in the rapidity and extent of the metazoan radiation during the Proterozoic-Phanerozoic transition J. W. Valentine; 3. Divergence and persistence of highly ranked taxa R. R. Strathmann; 4. Problematical taxa: a problem for biology or biologists? S. Conway Morris; 5. Metazoan evolution around the Precambrian-Cambrian transition J. Bergström; 6. Cladistic analysis of metazoan phyla and the placement of fossil problematica F. R. Schram; 7. Is fossil evidence consistent with traditional views of the early metazoan phylogeny? J. Dzik; 8. Lower Cambrian lagerstatte from Chengjiang, Yunnan, China: insights for reconstructing early Metazoan life Chen Jun-Yuan and D. D. Erdtmann; 9. Middle Cambrian biotic diversity: examples from four Utah Lagerstatten L. A. Robison; 10. Extant 'problematica' within or near the Metazoa G. Haszprunar, R. M. Riefer and P. Schuchert; 11. On the origin of the Bilateria: traditional views and recent altneratuve concepts R. M. Rieger, G. Hazprunar and P. Schuchert; 12. Problematic reef-building spongers R. A. Wood; 13. Beach and laboratory experiments with the jellyfish Aurelia, and remarks on some fossil 'medusoid' traces D. L. Bruton; 14. Early Cambrian medusiform fossils from Chengjiang, Yannan, China Sun Weiguo; 15. The enigma of conulariid affinities L. E. Babcock; 16. Evolutionary affinities of conulariids H. Van Iten; 17. Functional morphology of the Class Helcionelloida nov., and the early evolution of the Molusca J. S. Peel; 18. The arthropods of the Lower Cambrian Chengjiang fauna, with relationships and evolutionary significance Hou Xian-Guang and J. Bergström; 16. Early Palaeozoic arthropods and problems of arthropod phylogeny; with some notes on taxa of doubtful affinities A. M. Simonetta and L. Delle Cave; 17. New observations on the thylacocephala (Arthropoda, Crustacea) A. Alessandrello, P. Arduini, G. Pinna and G. Teruzzi; 18. Fossil Acarida: contribution of palaeontolgical data to acarid evolutionary history F. Bernini; 19. Are Protura really insects R. Dallai; 20. The Tully Monster and a new approach to analyzing problematica J. S. Beall; 21. Problematica-incertae sedis E. L. Yochelson.

This book represents a wide synthesis. It embraces not only general problems of animal classification of animals and new information on their molecular sequences that bear on their wider relationships, but also addresses more specific problems.