Romer's rule The proposal first made by the American palaeontologist Alfred Sherwood Romer (1894–1973), that the effect of many important evolutionary changes is to enable organisms to continue in the same way of life, rather than to adapt to a new one. For example, the evolution of bony elements that strengthened the limbs of fish enabled them to crawl over land to find new ponds when the climate started to become drier. The concept is close to that of the Red Queen effect.

Romer's rule The proposal, first made by A. S. Romer, that the effect of many important evolutionary changes is to enable organisms to continue in the same way of life, rather than to adapt to a new one. For example, the evolution of bony elements that strengthened the limbs of fish enabled them to crawl over land to find new ponds when the climate started to become drier. The concept is close to that of the Red Queen effect.