1. Simpson, G. G. Tempo and Mode in Evolution (Columbia Univ. Press, New York, 1944).
2. Valentine, J. W. Patterns of taxonomic and ecological structure of the shelf benthos during Phanerozoic time. Palaeontology 12, 684– 709 (1969).
3. Smith, A. B. Systematics and the Fossil Record (Blackwell, Oxford, 1994).
4. Hennig, W. Phylogenetic Systematics (Univ. of Illinois Press, Urbana, 1966).
5. Raup, D. M. Taxonomic diversity during the Phanerozoic. Science 177, 1065–1071 (1972).