Re: Perching, climbing, roosting was Re: 11th specimen of Archaeopteryx

[Tim Williams <tijawi@gmail.com>]

David Marjanovic <david.marjanovic@gmx.at> wrote:

>>  You know what the debate over how dangerous trees are for protobirds
>>  reminds me of? Back when I was learning about whale evolution, I
>>  used to think "but wouldn't water be really dangerous for those early
>>  stages of amphibious proto-cetacean life?" (there's crocs, sharks,
>>  hungry fish, etc)
>
> Not "etc.". There were crocs, there were sharks, but I don't know of any
> other big marine predators from the Paleo- or early Eocene.


Ironically, one hypothesis (Thewissen et al., 2007) proposed that the
ancestors of whales fed on land, and headed into freshwater as a
refuge when threatened.


Sharks were walloped at the K/Pg boundary (especially among marine
apex predators), although full diversity of the various neoselachian
groups had apparently recovered by the late Paleocene/early Eocene.



Anthony Docimo <keenir@hotmail.com> wrote:

>  You don't need a dozen separate families of creatures to eat protowhales* - 
> the fact that they were there and eating any protowhales
> they caught, makes them a good analogy to your statement that the trees were 
> too dangerous for protobirds, because of all the
> predators up there ready to pick a protobird off a branch and eat it.


"Proto-whales" had clear aquatic adaptations - though it's not
immediately clear why they first took to water (foraging?  safety?).
So the aquatic adaptations are present in proto-whales; scenarios are
then put forward in an attempt to explain these adaptations (like
"safety-in-water").  But with proto-birds, the "safety-in-trees"
scenario has it backwards.  There are no clear arboreal adaptations in
proto-birds. So there is the temptation to come up with
intuitive-driven explanations, and then provide reasons for why there
are *no* arboreal adaptations in proto-birds.  This is bad policy.  As
Scott Hartman said, we have to let the evidence drive our inferences,
not the other way around.








Cheers

Tim