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Re: origin of bats/reply to J. Headden






----- Original Message ----
> From: Jaime A. Headden <qilongia@yahoo.com>

> 
>   Why not? What bipeds (aside from this silly impression of bats) hve no 
> constraints on locomotion?

Only bats. They are unique, as you know. 
> 
>   There are a few birds out there that stand on one leg. Does them make them 
> monopeds? What constraint aplies to them and any other organism that just 
> stands 
> there on one leg? Bats don't even stand, they HANG. And the only other 
> hanging 
> vertebrates that use their feet for locomotion are various arboreal mammals 
> such 
> as tamanduas, sloths, kinkajous, and some primatiforms, as well as a few 
> birds. 
> These animals ACTUALLY WALK using their legs, and in the case of some birds 
> like 
> colies and parrots, can walk upside down (though often using their beak, so 
> they 
> are kinda tripeds, like kangaroos on occassion).

All true. And you're making my point. Bats hang bipedally. The question is: did 
their non-volant ancestors more or less do the same? Did they experience 
torpor? That's the big unknown. The taxon list I provided is our only source 
for clues currently. 
> 
>   You still have not argued for any reason why bats being "bipeds" MATTERS, 
> since all the material reasons to compare bats to other bipeds would be 
> locomotorally. There is no other animal in ... well ... existence known that 
> seems to move into flight from a hanging suspensory position, and that theory 
> has been pretty well debunked for pterosaurs for the numerous terrestrial 
> features posited for them and the absence of any bat-like aspects to ANY of 
> their legs.

When pre-bats became inverted bipeds their hands were no longer involved in 
locomotory matters. That freed the hands, as in pterosaurs and birds, to become 
something else. In the case of birds, foldable raptorial instruments and 
origins for flight feathers. In the case of pterosaurs, foldable display, 
flapping and gliding instruments.

Just get over this hump and you'll see the light.

DP  
> 
> 
> 
>   In which case they do not locomote.
> 
>   Cheers,
> 
>   Jaime A. Headden