[Taxacom] Paraphyletic tagging

Curtis Clark 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 
> feathers).

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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