Chapter 4: The Luck of the Ammonities

In this chapter Kolbert discusses the extinction event that killed the dinosaurs (Cretaceous-Paleogene). It starts off by describing the town of Gubbio made up of limestone. In the 1970’s a geologist named Walter Alvarez discovered the traces of a huge asteroid that struck the Earth in the Cretaceous period which later was later determined to have been responsible for the extinction of dinosaurs. The Alvarezes’ theory of the dinosaurs’ extinction was initially met with disdain but was accepted as it it explained why certain layers of the Earth were rich in iridium as found in the clay embedded in the limestone of Gubbio, and the extinction of dinosaurs. This brought support to the catastrophist idea that the history of the planet was characterized by sudden, global catastrophes that caused large numbers of species to go extinct. The point the asteroid’s impact of dust and debris proved to be worse than the actual asteroid is also brought up. As well as the survival of ammonites and the impact of the asteroid which caused them to go extinct as well. On page 90 kolbert states “ in times of extreme stress, the whole concept of fitness, at least in a darwinian sense, loses its meaning.” This shows how although ammonites evolutionarily useful traits the asteroid took a huge toll on their survival. This relates to the theme Science constantly changes the way we understand the world. After learning this Darwin’s theory of natural selection which is very well known is not as credible.