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Re: origin of bats/suspect trees?




On Jun 20, 2008, at 4:21 PM, Jaime A. Headden wrote:

David Peters (davidpeters@att.net) 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,>


Manatees?

: ) Martin and Feduccia have just entered the room. The single character mindset. Where's the suite Jaime?

<reduced distal ulna,>

Most cursorial mammals?

: )

<pedal proportions,>

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?

<wrist fusions,>

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?

: )


DP



Cheers,




David Peters davidpeters@att.net