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Re: Holtz v. Sereno???



At 11:45 PM 11/6/95, tuckr@digital.net wrote:
>> In a message dated 95-11-06 23:10:19 EST, tuckr@digital.net writes:
>>
>> >>  polytomy
>> >
>>
>> An unresolved node with more than two branches in a cladogram, as when
>> a
>> parent species gives rise to three or more daughter species but we can't tell
>> the order in which the daughter species arose.
>    Uh, huh.
>----
>-= Tuck =-
>tuckr@digital.net

        Whenever you look at a cladogram and you see two or more taxa
stemming from a single point on the stem of the cladogram, that's a
polytomy.  It just means we know that the organisms in question are
related, but we don't know quite how (that is, we don't know in which order
the taxa arose from the purported common ancestor).  You see polytomies all
the time, which arise primarily from lack of necessary specimens.  Does
that help?



Jerry D. Harris                       (214) 768-2750
Shuler Museum of Paleontology         FAX:  (214) 768-2701
Southern Methodist University         jdharris@lust.isem.smu.edu
Box 750395                            (Compuserve:  73132,3372)
Dallas  TX  75275-0395

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