Re: origin of bats/suspect trees?

[David Peters <davidpeters@att.net>]

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