PROSPECTS AND OPPORTUNITIES FOR STUDYING RATES OF EVOLUTION

The advent of greatly improved radiometric dating techniques with lower uncertainties, the development of new dating and correlation techniques, including vastly expanded quantitative biostratigraphic methods, and the possibility of reliable extension of orbital cyclostratigraphy into the Paleozoic all promise a great improvement in the ability of geologists to construct high-resolution temporal frameworks far deeper into the past. Temporal resolution of 100 kyr (0.02%) and eventually even 50 kyr into the early Paleozoic now seems likely. Such techniques have already allowed the generation of a high-resolution temporal framework for the Ediacaran-Cambrian radiation of metazoa, helped greatly narrow the duration of the great Permo-Triassic mass extinction thus eliminating some hypothesized causes and sharpening our testing of others, and narrowed the duration of the oceanic anoxic event at the Cenomanian-Turonian (Late Cretaceous) boundary. Questions now best explored in the late Cenozoic, including the relationship between climatic and evolutionary change, synchoneity of environmental change with evolutionary and ecological events, and rates of evolution can now be more rigorously explored deeper into the fossil record. But exploiting these new possibilities will require paleontologists to improve methods to integrate these methods, improve our understanding of the analysis of evolutionary rates, and confront the challenges of settings where geochronologic resolution may be greater than paleontologic resolution.