What metaphors are used in Wonderful Life: The Burgess Shale and the Nature of History by Stephen Jay Gould?

Wonderful Life: The Burgess Shale and the Nature of History focuses on a limestone quarry high in the Canadian Rockies known as the Burgess Shale. The Burgess Shale formed 530 million years ago and contains fossils of creatures from an incredibly ancient sea, where a plethora of frighteningly alien creatures lived and died. I suppose we can consider the unearthing of these relics as a metaphor of human evolution.