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Re: Vegavis gen. nov. - new anseriform in today's Nature (fwd)



----- Original Message -----
From: "John Bois" <jbois@umd5.umd.edu>
Sent: Monday, February 07, 2005 6:16 AM

What do you suggest to introduce _to the entire world_ at the end of the K
to kill off some 3/4 of species?

My ref. was a response to your astounding claim that predation has little effect, little _observed_ effect.

I only said "less effect than you seem to think". Remember your example is about predators and competitors imported from another continent. They didn't evolve in place.


In fact, if foxes were not possible to control, they probably would have
been even more devastating than they already are.

In the places where they've been shipped to, yes. In Europe foxes are not a pest at all. (Even though in some places in Bavaria they are now starting to enter the cities.)


> Behavioral flexibilty, smarts, sensory acuity, vertical take-off, > aerial
> agility, greater protection and nutritional support of fetus, etc., > etc.


Aha. Interesting. Then tell me what the behavioral flexibility of any
non-neornithean dinosaur were, for starters.

Behaviors don't fossilize. Extant birds and crocs have more fixed action patterns than extant mammals.

This is so generalized I don't think it's going to tell us much, if anything. Think of meerkats. I've seen a documentary that compared their problem-solving capabilities (in the wild) to those of primates. I don't know what it was anymore... perhaps an egg... anything the trick would have been to open the thing, but the meerkats just turned it around once in a while, and every few seconds they started _digging_ underneath it (scratching the earth away with their forepaws). Naturally it didn't work. Commentary: "They are used to solve problems by digging." If this isn't a fixed action pattern... in a successful little placental on a big continent... a carnivoran no less...


I don't need to bring up a gray parrot as a counterexample. A crow or pigeon will do.

Tell me why mammals didn't outcompete each other...

You're kidding, right?

Not at all. Tell me why the metatherian Peradectidae died out in the Miocene, instead of at the K-Pg boundary like all their fellow northern metatherians.


Tell me why you think enantiornithines and pterosaurs were incapable of
fast and/or vertical take-off. Tell me
why you think they were less agile. Tell me. Bring it on.

I read a paper on pigeon vertical take off...seems a very specific, highly derived ability.

Yes, it is. And? :-) Why do you think it appeared at the base of Neornithes, instead of much earlier or much later?


But what leaves me nonplused is your outlook on
evolutionary process. It is a kind of political correctness that argues for
all creatures to have equally valid abilities. They exist where they are
because they got there first and have not yet been dislodged by a mass
extinction.

That's not true. Local extinctions can of course empty niches just as well. They can of course be triggered by competition and predation as well as by impacts, volcanic eruptions, climate changes and the like -- but only when the competitors/predators evolved _elsewhere_ and immigrated _then_. If the predators/competitors evolved in situ, their potential victims would evolve _with them_, adapting to their presence while that presence is forming!


(Then what am I constantly waffling about the Great American Interchange? In such situations we can't a priori assume that every immigrant will have an exact ecological counterpart in the local fauna and full-scale competition will be launched. To pick examples from today's fauna, a thylacine may be almost the same as a dingo, but a koala isn't quite the same as a sloth, and a kangaroo is appreciably different from a deer or antelope or buffalo -- in food requirements, anti-predator strategies, requirements for reproduction and so on. I'm not saying a priori that competition and predation didn't cause any extinctions in the Great American Interchange. I'm just saying that we shouldn't rely on our ignorance, let alone the ignorance of past decades. Indeed it now looks like more of the South American fauna survived that was thought not long ago, and it looks like much -- perhaps even all? -- of the supposed victims perished some 300,000 years _before_ the interchange, in other words, many of the immigrants probably entered empty niches. Like raccoons are now doing in Europe, and the tree of heaven http://site.www.umb.edu/conne/jennjim/ailanthus.html -- Europe's only tree-shaped weed -- has done in the same place a century or less ago.)

Neornithines? The famous "heavy-bodied ground bird", which is basically
what *Vegavis* is, predating on or competing with azhdarchids at _any_
stage of the latters' life cycles??? That's hard to imagine. You'll need
something more similar to *Harpagornis* to get that point across.

Why the focus on azhdarchids?

Because they are the only known identifiable Maastrichtian pterosaurs. It looks like there were others, too, but they are unnamed fragments.


Well... there's a way out of this logical circle. We already know that the
Chicxulub impact coincided with the mass extinction, Keller
notwithstanding.
We don't know if the evolution of any "key apomorphy" coincided with it.

Behavioral flexibilty, smarts, sensory acuity, vertical take-off, aerial agility, greater protection and nutritional support of fetus, etc., etc.

Again: we don't know if the evolution of any of these features coincided with the K-Pg boundary.


Besides... greater protection and nutritional support of the fetus is not automatically an advantage. Imagine being late-term pregnant and pursued by a predator. The weight of the fetus slows you down. Chances are that you both die. Kangaroos have a special muscle in the pouch... when they are pursued too hard, Joey gets kicked out, and the mother survives (...and the waiting embryo can come out of its developmentary arrest). Likewise, marsupials never invest in stillbirths. If the newborn can't reach the pouch, it dies at a much earlier age than any stillborn placental, long before the mother has invested large amounts of energy that could go into surviving offspring.

Indeed I say that at least some enantiornithines were more susceptible to
the effects of the impact than at least some neornithines. Again, here's
why: The avisaurids and especially *Enantiornis* were rather large.
There's some evidence that both belong to a clade of predatory birds
-- if so, they
were likely terrestrial, and more or less top predators, which means they
were in the end dependent on green plant parts, and having smaller
populations to begin with. "Heavy-bodied ground birds" able to live off
seeds and insects should be expected to fare better. No known
enantiornithine seems to have had such an ecological niche. *Lectavis*, if
indeed a wader, and *Yungavolucris*, if indeed a diving bird, could have
been parts of freshwater ecosystems, thus much less directly dependent on
green plant parts and thus more likely to survive; but don't ask me if I
interpret too much into these leg fragments.

This all seems so _ad hoc_ to me. Maybe you're on to something. Do you feel confident in your reasoning?

Not terribly. You're right -- it _is_ ad hoc. I still feel scientific, though...:


How would you know if you were wrong?

If we found enantiornithine "heavy-bodied ground birds", for example. Or if we found Cretaceous hummingbirds.


Sometimes _much_ more outlandish hypotheses are scientific.

Lee Smolin: The Life of the Cosmos, Oxford University 1997

This book suggests that universes reproduce (by producing black holes) and evolve (the things that mutate being some or all of the parameters in the Standard Model of quantum physics). It's falsifiable: find Mr Smolin a neutron star twice as heavy as the Sun, and the hypothesis is falsified.

> Dromornithids, if they were like most birds, could not see at night.

It is _quite_ hard to believe that birds should be so night-blind unless
specially adapted (owls...). Could you explain this in more detail?

Read: Rowe, M. P. 2000. Inferring the retinal anatomy and visual capacities of extinct vertebrates. Palaeontologia Electronica 3:43pp

I've just read it again http://www.omnh.ou.edu/paleo/2000_1/retinal/issue1_00.htm and I can't find a mention of night-blind birds. All I find is that they retain lots of adaptations to diurnal vision that are unnecessary, but not outright impediments, at night.


The first answer you'll hear from an ecologist will be "because the
ecological niches of dromornithids were already occupied by other animals
outside of Australia".

This would be a very simple-minded ecologist. In the face of so much
successful invasion into "occupied niches", I wonder how one could take this
claim seriously.

There are lots of documented invasions into occupied niches -- but in every case I can think of the invader came from elsewhere, it didn't evolve in situ.


...the (bolide) hypothesis is still falsifiable, and thus scientific. You
are invited to falsify it. Good luck.

But whenever I bring in a piece of evidence...as in: species x actually survived but should not have...you respond with: "They were lucky". How does one falsify this? How would you know if you were wrong?

Whenever you say (so far) species x actually survived but should not have, I say the certainty in your saying it shouldn't have survived is too great. That's different from (unscientifically) not accepting a genuine falsification.