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Re: Question: Why did birds lose their teeth?




Wouldn't have it would need testing, given that one function of teeth is to 
retain items in the mouth -- at least as far as an increase in difficulty goes. 

A mechanical model would do it, though.



------------------------------
On Tue, Mar 11, 2014 5:44 AM EDT Vivian Allen wrote:

>I dunno man, how would you test the hypothesis that you couldnt shake your
>gullet clear if you have teeth?
>
>Viv
>On 11 Mar 2014 09:32, "don ohmes" <d_ohmes@yahoo.com> wrote:
>
>>
>> As you know, cattle egrets often follow agricultural operations such as
>> pasture mowing -- and they eat whatever is uncovered and small enough to
>> swallow whole, frequently making multiple attempts, using gravity and
>> headshaking to clear the gullet in preparation for another attempt. These
>> gullet-clearing operations would be greatly hampered by teeth, in the
>> absence of powerful jaw muscles to process these tidbits, usually mice or
>> toads.
>>
>> And clearing the gullet with a hind foot, while standing on the other
>> foot, is obviously less effective than using "hands", both mechanically and
>> mobility-wise -- the thieving tendencies of flock-mates being another
>> factor opposing successful ingestion.
>>
>> So the sequence is -- optimization of the wing reduces  wing claws (and
>> the need to climb) -- and the lack of wing claws reduces the desirability
>> of teeth -- which predicts a pattern of 'first go the claws, then the
>> teeth'.
>>
>> ------------------------------
>> On Tue, Mar 11, 2014 2:07 AM EDT Dr Ronald Orenstein wrote:
>>
>> >I would not expect this unless cleaning teeth was the only function of
>> wing claws ( and it isn't - viz the Hoatzin). Besides, living birds can use
>> their hind claws to reach the bill (they can certainly scratch their heads)
>> so why would wing claws be the ones toothed avians would use?
>> >
>> >Ronald Orenstein
>> >1825 Shady Creek Court
>> >Mississauga, ON
>> >Canada L5L 3W2
>> >ronorenstein.blogspot.com
>> >
>> > On Mar 11, 2014, at 9:59 AM, don ohmes <d_ohmes@yahoo.com> wrote:
>> >
>> >
>> >
>> > And I add, now that I have accessed a fresh battery --
>> >
>> > 1) the reconstructions of toothy birds with wing claws that I have seen
>> make it clear that the claws could reach the mouth, and thus could assist
>> in clearing the obstructions inevitable when working with a small,
>> tooth-infested intake tube.
>> >
>> > 2) it follows, as matter of selective logic, that if the claws
>> disappeared as the wing was optimized aerodynamically, then then the teeth
>> might follow -- flight being enough of an advantage in accessing prey
>> (among other things) to counteract the occasional escape the lack of teeth
>> might enable.
>> >
>> > 3) so! Does the record show a clear pattern of 'first go the claws,
>> then go the teeth' in toothed birds?
>> >
>> >
>> > ------------------------------
>> > On Mon, Mar 10, 2014 9:14 PM EDT don ohmes wrote:
>> >
>> >
>> > Hence the inclusion of the term "small biped" -- there are multiple
>> underlying allometric principles involved.
>> >
>> > E.G. -- A large fish falls off a given spear more easily than a small
>> fish does.
>> >
>> > And a smooth solid food intake port is no guarantee of trouble-free
>> dining -- I observed a cattle egret impale a toad so enthusiastically that
>> it ended up half way to the base of the beak -- had the toad been larger,
>> perhaps the bird's vigorous headshakes could have transferred enough
>> momentum to the toad to overcome friction -- or, had the toad been smaller,
>> the one foot per effort the bird could use to push on the toad might have
>> removed it. As it was, it was in a bit of trouble, pun intended -- it could
>> not open it's beak, and was totally mobbed by it's flock-mates, who wished
>> to steal the prize -- perhaps 50 birds, in all.
>> >
>> > This concept is easily demonstrated with a steak and a kitchen knife --
>> vigorous shaking might be required to remove a small piece of impaled meat,
>> while a heavier piece can be removed simply by pointing the knife downward.
>> >
>> > Also, the brute processing power attainable by terrestrial predators is
>> simply not possible for birds, as Pigdon explains in his initial post.
>> >
>> > Summing, small tubes are more easily clogged than large, and a very
>> small tooth is larger (relatively) to a sparrow's mouth than the daggers of
>> T rex, et al, are to it's massive head...
>> >
>> >
>> >
>> > ------------------------------
>> >> On Mon, Mar 10, 2014 8:17 PM EDT Mike Habib wrote:
>> >>
>> >> On Mar 10, 2014, at 4:53 PM, Dann Pigdon <dannj@alphalink.com.au>
>> wrote:
>> >>
>> >> Many non-volant toothed theropods also had long necks and short
>> forelimbs, making any sort of
>> >> grooming of the mouth via the forelimbs unlikely (tyrannosaurs and
>> carnotaurus are obvious
>> >> examples).
>> >>
>> >> In fact, the vast majority of non-avian theropods could not reach
>> their own mouths with their forelimbs, even those with relatively "robust"
>> forelimbs, such as allosauroids (nor can they reach any area in front of
>> themselves that they could see - which makes use in predation potentially
>> cumbersome). Interestingly enough, among theropods, some living birds are
>> among the derived taxa that can reach their mouths: with their hind limbs.
>> >>
>> >> --Mike
>> >>
>> >
>> >
>>
>>