[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Clade II



Nick, L. writes:
>               I'm not sure about that one. In Chiappe's "Late Cretaceous
>Birds of Southern South America", (1996) for example, there is a character
        What's the ref on this?  I am all a-quiver...

>matrix. Of 67 avian synapomorphies, Archaeopteryx and dromaeosaurs were
>both primitive for all 67 when states could be determined (thanks for
>pointing this out Tracy). So Chiappe's matrix cannot tell birds from
>nonavian theropods.  There is also the question of Mononykus, as well. 
                Ok, time out!  Nick, you are just plain wrong.  Archaey and
dromaeys are the OUTGROUPS of the study.  They are SUPPOSED to have all of
their character states coded zero.  The analysis relies on previous analyses
which place these groups as the outgroups of birds, and thus this has
already been established.  Your statement could be rewritten as "because
crocodiles aren't coded, Chiappe can't tell crocs from birds."  Phylogenies
are based on more inclusive phylogenies, to at least as far out as we have gone.
        Outgrouping is how you determine the character polarity of the
dataset.  Please go back and read a basic book on phylogenetic analysis.

>       Also, the same two-year-old might want to put whales and sharks
>together as well. Anyone can see that superficially these animals have far
>more in common than, say, whales and bats. 
        That's my point.  We teach them that they whales and sharks AREN'T
related, and viola', they have a nacient grasp of convergence!  Thanks nick.

        Wagner
+--------------------------------------------------------------------------+
| Jonathan R. Wagner                    "You can clade if you want to,     |
| Department of Geosciences              You can leave your friends behind |
| Texas Tech University                  Because your friends don't clade  |
| Lubbock, TX 79409                               and if they don't clade, |
|       *** wagner@ttu.edu ***           Then they're no friends of mine." |
|           Web Page:  http://faraday.clas.virginia.edu/~jrw6f             |
+--------------------------------------------------------------------------+