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Re: origin of bats/suspect trees?
On Jun 20, 2008, at 4:21 PM, Jaime A. Headden wrote:
David Peters (firstname.lastname@example.org) wrote:
<If the taxon lists are the same using morphology, the tree results
will be the same, if you employ at least 150 characters. That’s the
bottom line. That’s always been the bottom line. Doesn’t matter
which characters. Delete cranials. Delete post-cranials. Delete
axials. Delete every other character, or every tenth. If you test
like this, you’ll see what I mean.>
This is completely untrue. Try it yourself. Look at various data
sets for which well over 150 BPs are sampled and separate each gene
as a separate character group. Run each of these analyses
separately for the same taxa, using onyl taxa that are shared
between the sets. You will not get the same results, as the various
molecular analyses of birds have shown.
You just shot yourself in the foot. Few to no molecular results
replicate morphology. And I did say "using morphology"
Not to mention mammals. How do you think they got to the varying
positions for various groups in the first place?
Blood work is not definitive. Morphology rules.
<Getting back to bats: At least we should be looking for non-volant
mammals with SOME bat characters, like broad flat ribs,>
: ) Martin and Feduccia have just entered the room. The single
character mindset. Where's the suite Jaime?
<reduced distal ulna,>
Most cursorial mammals?
Oh, got me there. Bats are kinda in a category to themselves.
Don't forget, Onychonycteris has a short first toe.
However, if the recent paper on bat finger growth has anything to
say, extreme development in a short period will completely
obliterate proportional constraints in phylogeny. No ...
proportions are a TERRIBLE platform for comparison.
I said pedal, remember?
Let's not even go there. Many animals fuse their carpals, but
moreover, any animal that puts a great deal of stress and strain on
the wrist will begin to develop carpal anomalies and even develop
fusions. Look at moles, birds, etc.
<tooth counts, tooth shapes, etc.>
Ah, and this is constrained primarily by diet.
and yet, there are patterns and suites of patterns. You've got to
think about the whole critter.
Dietetically, for example, bats and MOLES are highly convergent in
dental anatomy, so much so that they were allied to the
insectivores for this very reason. Genes seem to say otherwise.
Given that tooth shape and count vary for as basic a reason as jaw
length, using this as a constraint is a terrible idea. it is also
rather problematic to compare mammal groups to one another because
of their teeth due to their convergent nature. It's useful for
specific separation, but only during in-group comparisons. Sure,
you'll get features such as accessory cusps in the talonid that are
comparable in some taxa, but what about the crenellated, blade-like
premolars of eutherian dermopterans and the similar teeth of non-
eutherian multituberculates? Though for the most part the
similarities end there. Incisiform incisors in kangaroos and rabbits?