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Re: The birds vs. the pterosaurs



> >   In your example, well-drafted in my opinion, there is a
> > distinct niche partitioning between the F-22, the C-17, and a
> > MiG, that suggests that their specialties, not their relative
> > performances, owes to them being varied. I am not familiar
> > with
> > aircraft, however, but I have been working slightly on flight
> > dynamics in pterosaurs and early bird evolution to study the
> > mechanical ability to evolve wings and feathers, and those
> > wings
> > of a pterosaur by the Late Jurassic were miles ahead of that
> > of
> > birds. This was true by the time of the Late Cretaceous, as
> > well. We get pterosaur-like birds (soaring, high-load bearing,
> > heavy performance dynamics) in only stork and vulture and
> > eagle lineages. [albatrosses?]

...which, by the way, appeared quite some time after the K-T extinction.

> >   There are mechanics that suggest that the largest known
> > pterosaur, at 200 kilos,

So much? I thought *Quetzalcoatlus* was estimated at 86 kg.

> > could bear on its wings _well_ twice
> > that value.

:-o Cool...

> > Birds just survived the K/T, inexplicably.

By far most died out, anyway. Those that did survive (still hardly known
:-( ) probably didn't directly depend on photosynthesis, means they lived in
e. g. freshwater environments.

> > Champsosaurs outperformed the crocs in the sea, but were gone
> > by
> > the Eocene extinctions, but crocs did not take to the seas,
> > but
> > rather stayed near the shores in their global transgressions,

???
There were marine champsosaurs? As far as I have understood it, there were
champsosaurs in the freshwater and crocs in the freshwater and the sea
before the end of the Eocene. Champsosaurs and crocs apparently did
partition niches (I've just copied the abstract of a paper from the 1999 SVP
meeting which says something like that, but I haven't read it yet... :-( ).
In the Eocene-Oligocene catastrophe the sea crocs (Dyrosauridae) perished,
leaving the already evolved whales (which were severely hit, too, AFAIK)
alone, and the champsosaurs _nearly_ perished (the BASALMOST champsosaur,
*Lazarussuchus* [or is it *-saurus*?], is known from the Oligocene... %*) ).

Anyway, the oldest champsosaurs are known from the Triassic, as are the
oldest crocodylomorphs, which seem to have been terrestrial and took to the
fresh and salty waters after the extinction of the distantly related
parasuchians = phytosaurs. So these 2 groups seem to have got along quite
perfectly with one another.

> > cross, but for all their adaptability, they survived (not one,
> > but three global extinctions) and even _diversified_
> > terrestrially in the absence of some land predators (big
> > predator birds, carnivoran mammals, presumably also
> > dinosaurs).

In the _presence_, you mean?

BTW, pterosaurs were surely as warm-blooded as birds. The mere fact that
they were flapping fliers (even though late, big ones specialised in
soaring, analogous to birds), while an ectotherm can't mobilise enough
energy to sustain flapping flight, is very good evidence. Furthermore, some
sort of fur (not homologous to mammal fur, might eventually be homologous to
feathers) has been found on several pterosaurs (*Sordes*, *Rhamphorhynchus*
and *Pterodactylus* come to mind); insulation on ectotherms is not expected,
because it would drastically cut down heat exchange with the environment,
but would be needed in endotherms of their (small) size.