[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Question: Why did birds lose their teeth?



Granted there might be allometry involved, though some small non-avian 
theropods couldn’t reach their mouths, either. I really don’t know how 
important food manipulation at the mouth might be for early birds (it’s an 
interesting idea), my point was just to reinforce the observation that 
non-avian theropods were, on the whole, not adapted to reach their mouth with 
their forelimbs. Birds aren’t, either, but many of them can use the hind limbs, 
instead. But maybe toothlessness is still adaptive. It very well might be 
(though I personally prefer a contingency explanation).

—Mike



On Mar 10, 2014, at 6:14 PM, don ohmes <d_ohmes@yahoo.com> 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
>> 
>