Abstract
Punctuated equilibria (fondly known as "punc eq", and hereafter referred to as PE) theories are all composed of two claims. The first claim is merely a paleontological observation, or what Stephen Jay Gould calls the "geometry" of PE. As will be elaborated below, this claim is that: 1) transitional forms are lacking between species, and 2) a species morphology does not change substantially throughout its range in the fossil record. Because, with minor variations, it is a common element in all PE theories, the paleontological observation may just as well be considered punctuated equilibria sensu stricto. The second claim of each PE theory is a mechanism proposed to explain the paleontological observation - usually a speciation mechanism to account for the lack of transitional forms between species. The variety of these mechanisms accounts for a vast majority of the variations upon PE theory that exist. Since PE theories differ predominantly in their second claims, it may be said that PE sensu lato is a statement of the paleontological observation along with a mechanism for its explanation.