Author's note: these pages were written some years ago. I am not planning to update them. For a more current coverage, see the Palaeos website (to which many links on these pages point to anyway. More info here
The Monophyletic taxon,
also called a clade, is the
building block of the cladistic system of
taxonomy. It refers to any group of organisms that includes the most
recent common ancestor of all those organisms and all the descendants of
that common ancestor.