Predictivity & Tetrapoda nightmare

Ken Kinman kinman2 at YAHOO.COM
Wed Feb 16 14:11:24 CST 2005


Hi G.B.,
       Good to see another fellow spiderman in the group.  However, I didn't recommend the Tree of Life page as a good place to "brush up" on vertebrate systematics.  Rather it is a good place to become confused and/or shake one's head in disbelief that it's come to this.  Anyway, modern reptiles are not synonymous with Lepidosauromorpha (which excludes crocodiles and usually turtles as well; not to mention birds which strict cladists want to formally shove into Reptilia as well).

      As for a taxon like "Reptilomorpha", we already have the notorious Reptiliomorpha.  Once a subclass of Amphibia to include those closest to amniotes, such as anthracosaurs and seymouriamorphs, it was another one of those taxon names hijacked by the strict cladists.

      Reptiliomorpha is now cladistically defined to specifically include Homo sapiens!!!  YUP, you read correctly, you and I are (and by cladistic definition, MUST be) reptiliomorphs.  At least that's what they were sticking with as of the big PhyloCode conference last July.   Hey, they had to change it, because when their cladograms changed, their earlier cladistic definition suddenly included all the living amphibians as well (yikes, how embarrassing).  It had become more inclusive than their crown group Tetrapoda!!

      Anyway, these are the people who want you to believe that paraphyly is an illusion or at least "unnatural".  And exgroups don't need to be invented, nature did that for us (they are clades, like Aves and Mammalia).  If you do delve into the details, strict cladism is getting us deeper and deeper into a taxonomic quagmire when it comes to vertebrates and a lot of other taxa that have many fossil taxa and lots of homoplasy.  This is much deeper debate than just semantics, although they do use semantics to prop up their case (such as paraphyly supposedly being "unnatural").

   -----Cheers,
                  Ken Kinman***

***I personally refuse to classify myself as a member of a clade Sarcopterygii.

**************************************************
G.B. Edwards Jr. wrote:
(1) Reptilia is the name of non-mammalian (and related) anthracosaurs, like Synapsida is the name of non-reptilian (and related) anthracosaurs (as above, Reptilia are no more all 'reptiles' than synapsids are all mammals); maybe this group should have been called something like 'Reptilomorpha' to eliminate all this confusion about Reptilia with 'reptiles;' (2) If turtles aren't diapsids, then they're 'testudine anapsid reptiloids;' (3) Modern 'reptiles' are synonymous with Lepidosauromorpha.  This eliminates the illusion of paraphyly and doesn't require the invention of ex-groups.  Surely someone has suggested this already, but I don't keep up with vertebrate systematics literature.
At least that's what it looks like to me, based on the web trees, and without delving into further details.




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