INCREASING RETURNS, ECOLOGICAL FEEDBACK AND THE TRIASSIC RECOVERY

The Early Triassic is marked by low-diversity benthic assemblages of opportunistic forms, continuing, severe, carbon isotopic fluctuations and the remarkable diversification of ammonoites, conodonts, and, later, icthyosaurs. The transition to the Anisian (Middle Triassic) marks the true recovery, with stabilization of carbon isotopes, diversification of benthic, planktonic and nektonic marine groups, the reappearance of Lazarus taxa, and of first scleractinian reefs. The carbon isotopic studies of Payne have established that environmental perturbations were likely the major cause for the delayed Triassic recovery, focusing attention on the dynamics of events from the Smithian-Spathian boundary into the Anisian-Ladinian. The application of logistic growth models suffers both from a lack of positive feedback effects and a lack increasing returns with scale, and externally imposed limits to growth. Although hyperbolic models incorporate positive feedback effects through dependency of species interactions for increased diversity, they can still externally limit growth. Endogenous growth theory from economics suggests a way out of this dilemma, with increased diversity a consequence of the spillovers from ecosystem engineering and niche construction. Applied to the Triassic recovery, such an approach suggests the recovery was driven by endogenously driven growth; increases in what ecologists commonly term carrying capacity.