Fig. 2.
—Divergence time estimation between species. Numbers at nodes represent divergence time estimates in millions of years ago (Ma). Red squares indicate nodes calibrated by fossil records.
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.