Re: "Common ancestor" in cladistics

[John Bois <jbois@umd5.umd.edu>]

> --- Manuel <mparrado@peoplepc.com> wrote:
> > Is there such a thing as an actual common ancestor or
> > is that an abstract concept?  If there are, how are they identified to be
> > such?  Some examples of actual dinosaurs would be great.


It's an actual thing.  You and your sister share a common ancestor--your
mother.  The idea is that your sister becomes reproductively
isolated and her progeny lead to new species in time.  As others have
said, it would not be possible to ID this in the fossil record.  Students
buy the idea of evolution by n.s., but tell them that their own existence
depended upon the survival of a certain fish in the Devonian and they will
balk.