Fig. 1
From: Views from Understanding Evolution: Parsimonious Explanations for Punctuated Patterns
Hypothetical stratigraphic records containing fossil snail shells. (a) A punctuated pattern in which one species appears to have quickly evolved into a new species. (b) A punctuated pattern in which one lineage appears to have quickly produced two daughter species, one with a form identical to the ancestor and one with a distinct form. (c) A pattern recording slow and steady evolutionary change