Controversies concerning dinosaurs abound. In this chapter I take on four that continue to influence, even if in small measure, our perceptions of dinosaur extinction. Each of the four controversies is fueled by disagreement about one or more of three fundamental questions: how many? how fast? and when? My survey takes on these four controversies in the order of least to most hotly contested.
In order to understand what occurred at the K/T boundary, we need a good fossil record as far before and after the boundary as we can measure. The reason for this is quite simple. If we wish to understand the pace and magnitude of faunal turnover precisely at the end of the Cretaceous, we need other reference faunas bracketing the boundary. Only in the Western Interior of North America do we have well-sampled vertebrate faunas bracketing the K/T boundary. Fauna refers to all the species found at similarly aged localities in a well-circumscribed area ranging in size from a few square feet to tens of square miles. Faunas of similar age are grouped together as ages. The ages leading up to the K/T boundary are, from oldest to youngest, Judithian, Edmontonian, and Lancian (figure 3.1). These three ages are especially well represented in the western states (figure 3.2). The ages