Chapter 2, A Background for the Burgess Shale Summary and Analysis

The purpose of Chapter 2 is to prepare the reader for the tale of the Burgess Shale by providing her with the necessary background to understand the "drama" of the tale. Gould begins by explaining the way that paleontologists (and other scientists) divide up historical epochs. There are eras, which are composed of periods, which are themselves composed of epochs. The pre-multi-cellular-life era is known as the Precambrian Era and comprises the first 4 billion years of Earth's history. The boundary between the Paleozoic and Precambrian eras (570 million years ago) is marked by the "Cambrian explosion" or the diversity of life that arose from the first multi-cellular creatures. The Precambrian Era contains geological, non-biological time and the advent of single-celled life. The Burgess fauna follow the beginning of the Paleozoic Era...