Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Hierarchical clustering analysis of shape PCs using Ward's method. Fossils are in bold and red, while extant species are in black. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
