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Re: Response II



>      On the one hand, Morokweng was said to be relatively innocuous
because
> it struck so far south, on the other, it supposedly wiped out NA
diplodocids
> and *Allosaurus* (while Gondwana titanosaurs, stegosaurs, dicraeosaurs,
etc.
> survived!)  If a Chicxulub-size blast can create a global dust cloud,
> location of impact should be an irrelevancy.

The location of Morokweng may mean that the global dust cloud didn't last as
long, there was less acid rain etc.. However, this must all yet be tested,
very little is known about the J-K transition in general.

> Fires started by lava can spread far so K-T ferns need not be atop lava.

This requires, however, that there were such eruptions on every continent.
The Deccan flows were limited to the Seychelles and India (and, AFAIK, they
paused at that time anyway).

>       Unlike Tyrannosaurus, ceratopsids always seemed endemic to
Cordillera.

Ceratopsids, yes, but there is *Turanoceratops*, a close relative, from
Uzbekistan.

> *T-rex* evolved when the regression began, but probably
> couldn't spread until it was far advanced c. 65 Ma.

1. It's *T. rex*. No hyphens are allowed in Linnean binomials.
2. Why shouldn't it have spread to Euramerica sooner (considering
lambeosaurines did)?

> Overrun by chasmosaurines,

... these came from where?

> the Lancian ecosystem may have
> collapsed when many *T-rexes* migrated, easing predation pressure and
causing
> ceratopsid numbers and food demands to increase even more.

The remaining individuals of *T. rex*, however, should have multiplied again
due to lack of concurrence.

> The replacement
> of overgrazed, good vegetation with ferns doomed the Lancian herbivores,
> which were too large or specialized to live elsewhere when their rich
habitat
> was ruined.

I'll repeat that the fern spike also occurs in New Zealand. (Where else?) No
Lancian herbivores there. And I'll repeat that no precedence case is known.

>       So *Pararhabdodon* could run away fast? *T-rex* was also fast!

The cheetah is currently the fastest animal on Earth. _It_ is endangered,
not its slower prey.

> No lambeosaur survived alongside T-rex in Cordillera, despite exposure to
> earlier tyrannosaurs.

Is this negative evidence?

> Foreign prey wouldn't have stood a chance.

I have told you the ecological reasons why extermination that way can't
happen, haven't I?

> Dinosaurian prey was more vulnerable to extermination than many extant
forms
> because it was relatively large and easy to find, and had smaller
> populations.

*T. rex* was also large and easy to find -- so it had a harder time
ambushing than smaller predators -- and must have had small populations
because it was so large and on top of the food chain.

> Moreover, *T-rex* had extremely acute senses

Hard to tell, but I don't think its senses were more acute than everything
known today. I'd be very surprised if it had had more acute eyesight than
the average eagle, for instance.

> and was very adept at finding prey.

This is rather untestable.

> Perhaps certain crocodilians,

One croc bone with *T. rex* bite marks please.

> turtles,

Far too small (and AFAIK too rare) to sustain a 14-m-long theropod!!!

> pterosaur nests,

As I wrote, imagine a cat surviving on insect eggs. Furthermore, we don't
know where azhdarchids nested -- they may well have nested in places
inaccessible to theropods (offshore islands and such).

> etc. helped sustain the T-rex population long enough for it to complete
the
> elimination of non-Cordilleran dinosaurs.

This is damn unlikely. Oh, er, and evidence please :-)

> Also, if lands were connected,
> incoming

Fleeing? Stampeding?

> prey from remoter ecosystems may have sustained *T-rex* while it
> annihilated the nearest non-Cordilleran quarry, a process repeated as it
> continued to migrate until nothing but the nondinosaurian substitutes were
> left (some of which also disappeared.)

Which ones?

> The brown tree snake soon outnumbered
> Guam prey as it annihilated the latter, even mammals.

What, outnumbered all its prey? A predator-prey ratio in favor of the
predator???

BTW, the brown tree snake is bradymetabolic, it needs to eat rarely. And it
can subsist on very small prey. Not so *Tyrannosaurus*.

>      There is ample evidence that small theropods were nest raiders e.g.
> *Troodon* teeth associated with hadrosaur nests.

Not _specialized_ nest raiders, though. Lots of terrestrial vertebrates will
raid any nest on occasion, but the only specialist known to me is an African
snake.

> Oviraptorids evolved as specialized egg eaters (see Currie.)

See Currie when? 1985? What's the ref?

Others have suggested oviraptorids were specialized mollusk eaters or even
specialized herbivores. The only consensus is that they were rather
specialized...

> Ornithomimids probably relied on
> dinosaur hatchlings for the bulk of their diet.

Ah. Interesting. Evidence please.
I'd say ornithomimids ate anything that was small enough, and several
specialists have suggested they were herbivores (based on their relatively
strong cutting beaks).

> And there wasn't much alternative to nests. No small theropod could have
survived for long without other
> dinosaurs.  Mammals were mostly inaccessible (nocturnal, arboreal,
burrowing)

LOL. _One_ probably arboreal mammal is known from the Mesozoic,
*Henkelotherium* from LJ Spain. You do know that one specimen of
*Sinosauropteryx* has mammal jaws in its gut?
>From the Paleocene we know arboreal multituberculates, plesiadapiforms etc..
But AFAIK no sooner.
Troodontids are often thought to have been nocturnal or crepuscular, based
on their big eyes. Ornithomimids also have big eyes.
AFAIK, no known Mesozoic mammal exhibits burrowing specializations (which
doesn't mean too much, but is evidence that all spent much of their
lifetimes on the surface.)

> as were many birds and reptiles.

For the latter at least... a specimen each of *Compsognathus* and
*Sinosauropteryx* has a lizard in the stomach. And a regurgitated pellet
that contains 4 young birds is known from the EK of Spain...

> Insects and worms were woefully inadequate.

But pterosaur eggs were adequate for *Tyrannosaurus*?

> Crocodilians, varanids and turtles could probably withstand small
theropods,
at least.  So could pterosaurs.

Why, if herbivorous dinosaurs couldn't withstand *Tyrannosaurus*?

>      K-T sea levels may have fallen 100m.  In any event, there was a big
> difference between Mesozoic and Cenozoic sea life: the former was far more
> thermophilic.

_W_
_R_
_O_
_N_
_G_
_!!!_

This is a truism. Temperatures remained quite constant through the K-T
(apart from the impact-caused disturbances that can't have lasted more than
1000 years or so) and _ROSE_ in the Paleocene when, apparently, methane
hydrate dissolved in the Tethys!!! Palm trees grew in _northern Greenland_
in the Eocene!

> Long before the Ice Age, sea life was adapted to Cenozoic
> cold.

1. How come?
2. What Cenozoic cold? The HOT temperatures I mentioned were here to stay
until the Oligocene (when Antarctica froze)!

> That was the key difference between a whale and a mosasaur.

Early whales enjoyed slightly warmer seas than mosasaurs.

> Even a modest fall in ocean temperature

, caused by an impact =8-) ,

> might've doomed Mesozoic marine life.

> And regression could have contributed to cooler temperatures,
> since it meant the oceans had less surface area to be warmed by the sun.

Evidence for cooler temperatures please.