Exceptional fossil record: distribution of soft-tissue preservation through the Phanerozoic

Preservation of soft-bodied fossil biotas (Konservat-Lagerstatten) that preserve traces of volatile nonmineralized tissues (readily degraded by bacteria) are not evenly spaced through geologic time. When compared to outcrop area, exceptional faunas appear to be over-represented in the Cambrian and Jurassic. These concentrations n time correspond to particular environments, indicating that controls on the distribution of exceptional faunas may have operated on a global scale. The reduction in the number of exceptional faunas after the Cambrian may reflect the evolution and diversification of deep bio-turbators. Specific conditions favoring stagnation and episodic burial were required to ensure preservation in younger rocks.