[Taxacom] Paraphyletic tagging
lists at curtisclark.org
Fri Oct 3 14:39:01 CDT 2014
To be clear, although Stephen's answer works for the extant species, Ken
guessed that I meant more globally.
On 2014-10-03 7:22 AM, Kenneth Kinman wrote:
> I would rather phrase it: "Amniotes lacking the synapomorphies
> of Mammalia and Aves".
So we've created a taxon based on a lack?
> Hair and feathers would not be the best synapomorphies to pick as they
> evolved too gradually (even baby Tyrannosaurus rex may have had
And there are even hairy things in some Ornithischia that have been
interpreted as being homologous with feathers. I'm not saying that
thecodonts had feathers, but if a thecodont fossil with clear feathers
was discovered, I wouldn't be astounded.
> For Mammalia, the best synapomorphy so far discovered seems to be when
> the three ear bones decoupled from the mandible.
But unless that happened in a single speciation event, there is still
the issue of where in a gradual shift do we draw the line.
Curtis Clark http://www.csupomona.edu/~jcclark
Biological Sciences +1 909 869 4140
Cal Poly Pomona, Pomona CA 91768
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