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Re: birds/dino-birds with teeth

> I don't know why a beak would extend progressively
> further from the labial margin of the
> (pre)maxilla/dentary in a protobird. Though I can say
> that the usefulness of teeth would be reduced once the
> beak impeded their ability to sink into flesh. If the
> first beaked animals were insectivorous, I don't
> suppose teeth would be greatly needed.

I agree. Another possibility might be that a beak provides a smooth cutting
edge if it's toothless; this might apply to confuciusornithids with their
strong, akinetic skulls (Feduccia thinks they were folivores, much like a
hoatzin... who knows). But then the toothless pmx of Hesperornithiformes and
Ichthyornithidae is totally counterintuitive... or means that they inherited
this feature from an ancestor which did something else with its beak.
        Well, a skull on *Limenavis* would definitely be interesting :-)
        Why would a beak impede teeth? Do you mean it lay lateral to the
teeth, corresponding to lips rather than to cornified gums?

> The triangular
> skulls of Archie, *Sinornithosaurus*, and a few other
> basal birds and Deinonychosaurs look like they could
> wiggle their way into loose bark. [...]
> The propulsion joint in avian skulls might
> also be good at getting those stubborn bugs that are
> just out of reach.

Interesting ideas. Actually, I can't remember any other idea what prokinesis
could have evolved for :-)

> The "Aye-Aye" theropod's finger could be
> further evidence of insectivory if it used it in a
> similar fashion as the animal it was nicknamed after.

Well, it appears to be a specialized, derived lineage on its own, so that
might not tell much about birds.

> You could even combine the ideas if
> you wanted. There could have been little fish-eaters
> sitting in trees overhanging lagoons waiting for prey
> to swim below.

Good idea -- but then I'd still think the reverted hallux should come first