Gunther Eble

Paper #: 99-04-028

The dynamics of origination in the fossil record of three marine groups (mollusks, echinoderms and fishes) and three terrestrial groups (mammals, insects and plants) is analyzed in this paper. Four hypotheses are tested: (1) secular decline in lineage origination; (2) secular decline in evolutionary innovation; (3) diversity dependence of lineage origination; (4) self-organized criticality of lineage origination. A decline in lineage origination and in the production of major innovations is present in all groups, suggesting controls that transcend the land-sea distinction. The relationship between diversity and origination appears to be strong in the sea and weak on land, a difference that might imply environment-specific controls. Mixed support for a logistic dynamics of origination is found. Finally, no general support for a self-organized critical behaviour of origination is found, with the predictions appearing to hold robustly only in insects and pteridophytes/gymnosperms.