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.
The lines at the base represent one item in the assemblage, and each branch represents a segregated morphological group (type variation) based on similarity. The color-coded circles beneath the branches represent the group/type’s chronological horizons to which they belong.
