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Re: Archie bones



GO writes:

>>Can I assume you are kidding here?  Anyway, I thought that it was now known
>>that the bones were, in fact, hollow in Archaeopteryx (and if Archie was a
>>specialized diver I will personally eat the entire Berlin specimen, bedrock
>>and all).
>
>No more specialized than a cormorant or an anhinga. But certainly not as
>specialized as a loon, penguin, or _Hesperornis_, of course.

My God, you weren't kidding!  Okay, let's get this straight:  I am not aware
of one single feature that Archaeopteryx shares with cormorants and anhingas
(and I am talking about convergences here, obviously - certainly nobody is
implying that Archie is a cormorant) that can be interpreted as an
adaptation for diving.  In fact, though Archie is arguably a pretty
specialized dinosaur, it strikes me as a very generalized bird.

If you are under the impression that cormorants and anhingas do not show
skeletal specializations for diving and associated prey capture, you are
incorrect.  See Johnsgard, "Cormorants, Darters and Pelicans of the World",
pp. 34-41, for a summary of these.  They include: elongation of the
postacetabular portion of the pelvis (for attachment of musculature involved
in foot-propelled diving); well-developed patella; adaptations of the
cervical vertebrae for thrusting (especially in anhingas); a relatively
sturdy ribcage (in cormorants) to withstand water pressures; etc.

>
>Hey, there were lagoons a plenty in Bavaria of 145 Ma. Maybe some of those
>_Archaeopteryx_ skeletons got there by drowning during dives. Wouldn't it be
>neat to find fish scales in the stomach of one of those specimens? Of course,
>this still wouldn't prove they dived after the fish, only that they ate (or
>scavenged) them.

As you said yourself in relation to proterosuchids, the fact that the
specimens ended up under water proves nothing, and I know of no feature in
Archie that suggests aquatic feeding habits.  As I suggested in an earlier
post, they could have nested on lake islets to avoid predators and flown
regularly over water to get to feeding grounds (as some nutmeg pigeons do
today).  
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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