Posted by Troy on March 24, 1999 at 08:34:17:
In Reply to: Monophyletic/Paraphyletic posted by SNYDER on March 13, 1999 at 13:36:56:
monophyletic = a group (taxon) that includes all the descendants of a common ancestor. i.e. snakes are thought to be monophyletic because, based on all evidence to date, all snakes evolved from a single common ancestor
paraphyletic = a group (taxon) that does not include all descendants of a common ancestor. in other words, some of the descendants of the original common ancestor are classified in a different group. i.e. lacertilia is a paraphyletic group because the common ancestor of all living lizards has descendants that includes snakes (serpentes) and amphibaenians.
Another example of a paraphyletic group would be the Reptilia, because the lizards, snakes, crocodilians, and turtles share a common ancestor with birds and (probably) mammals.
