On 10/26/05, Denver Fowler <df9465@yahoo.co.uk> wrote:
This is in some respects a 'split lineage', but to
think of a cladistic diagram as a 'family tree' is
misleading. It's a statistical diagram, nothing more:
Well put.
a split may indicate a shared <unknown> common
ancestor between taxa, or that one of the taxa is
infact, the ancestor of the other. it is not possible
to determine which is which using this method, because
cladistics makes no assumptions of time/age of taxa.
However, you can use a cladogram combined with data on the time ranges
of your OTUs to identify *potential* ancestors. If two sister taxa, A
and B, are scored identically except that A lacks certain derived
traits that B exhibits, and every member of A occurs earlier than
every member of B, then A *might* be ancestral to B (although this
can't be proven).
--
Mike Keesey
The Dinosauricon: http://dino.lm.com
Parry & Carney: http://parryandcarney.com