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

Re: The question of beaks in simplistic terms



David Marjanovic writes:

> Okay. But does this even hold when the head feathers are 
> preserved (which isn't the case in any *Archaeopteryx*)?

Well, I tend to think this type of situation could very well be one as 
mentioned in my decaying bird examples. Differential decay matters. I've found 
them with the keratinous beak and flesh gone, but still having tuffs of 
feathers around the skull. I guess something else that's interesting is that 
the keratin on the nails is outlined in some of the fossils... the reticulate 
are sometimes even there... but the tougher podotheca isn't. Differential decay 
matters. There is no pattern... no consensus... to the preservation that allows 
you to diffinitively conclude that a keratinous covering wasn't on the the 
premax/max of these animals. You are pretty much grasping at straws if you say 
otherwise.

Oh, it is true that podotheca does vary a lot in birds today. Example: Two 
gulls. I'm not sure, but they might have belonged to the same ring species... 
as being connected over a cline. One had podotheca like a baby's bottom. The 
other was like a turtle's arm. So, throw that into the mix.

The only real way to learn taphonomy is the same as in learning geology... see 
what happens now and compare it to what we you see in the record.

David Marjanovic writes:

> Depends. I'm sure that all toothless ornithomimosaurs had a > beak, for 
> instance. *Pelecanimimus* is another problem.

Exactly. Confounding isn't it? I guess that the entire thing here is that we 
didn't have scales one day... beaks the next. Even though I hope some people do 
not think that, you sometimes get the impression when they give their arguments 
that that is what they are saying. A continuous covering on the premaxilla... 
though thin... is not a nutty idea. And the thing is... a thin covering would 
preserve no better than seperate scales. Why would it???  You could go and 
apply this back to your first comment about feathers on the head but no beak... 
Scales weren't preserved on the faces either. So.......

Kris