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Re: Question: Why did birds lose their teeth?



Have any studies been done on the comparable drag resistance in air
and water for bird and turtle beaks respectively compared to
similarly-shaped toothy, skin-covered alternatives?

On Tue, Mar 11, 2014 at 9:53 AM, don ohmes <d_ohmes@yahoo.com> wrote:
>
>
> 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
>>> >>
>>> >
>>> >
>>>
>>>
>