
Survival in the first hours of the Cenozoic (2004) [pdf] - mr_toad
http://uahost.uantwerpen.be/funmorph/raoul/macroevolutie/Robertson2004.pdf
======
swagasaurus-rex
> "The intense IR radiation would have originated from the entire sky.
> Darkness would have been eliminated worldwide for several hours and shadows
> curtailed. Shadowing effects would have been restricted to a direct
> proportion of the fraction of the sky blocked by a massive object. An
> organism at the foot of a lengthy vertical cliff, for example, would have
> been spared radiation from just under half the sky. It would not have been
> sufficient to shelter in a gully, under an isolated tree, or even under a
> sparsely forested canopy. Life confined to Earth’s surface would have
> perished well before incineration."

------
rwallace
‘‘No one has yet been able to explain under any theory why the crocodiles and
turtles survived and the dinosaurs did not.’’

Sure they have. Crocodiles are cold-blooded; they are known to be able to
estivate for months without food, waiting for better conditions. Birds and
contemporary mammals are small; they can hide, and survive on small scraps.
Dinosaurs were both big and warm blooded; the resulting metabolic demand is
fatal in hard times.

Not saying the authors aren't right about being able to find shelter against
heat pulse also being a factor, of course. But it's not the only explanation.

~~~
sandworm101
The cold v. warm blood thing is far more complex. For instance, warm blooded
animals can handle slight changes in temperature better than the cold blooded.
A wolf's reproductive cycle may be tied to the weather, but a degree or two
either way won't really impact the development of its live young. But a degree
or two for a croc egg and it might not survive. Or all the crocs one year are
male because egg temperature can impact sex selection. If a meteor causes
havoc with the climate, that warm blood under some warm fur could be a real
advantage.

~~~
rwallace
Oh, to clarify, when I talk about that, I'm not talking about temperature
tolerance - that's really more of a secondary byproduct - but metabolic
demands. A warm-blooded (i.e. fast metabolism) animal needs an order of
magnitude more food than a cold-blooded (slow metabolism) animal.

~~~
tremon
From what I've read, dinosaurs were not warm-blooded due to their fast
metabolism (endothermic) but due to their size and associated heat capacity
(homeothermic). That would have made them relatively less susceptible to
starvation than present-day mammals, but given their size, they would still
require plenty of food.

~~~
sandworm101
The big ones. Most were not the movie giants and so were probably much more
cold _ish_ blooded. It is all a bit of an oversimplification. Some big fish
(white sharks) can have internal temperatures a few degrees above water temp.
There are all sorts of middle grounds between warm and cold blood.

------
goatlover
> "The real question is, how did the others—how did any animal—manage to
> survive? [Impact theorists] have got to come up with a hypothesis that puts
> equal weight on survival. So many of these catastrophists want to kill the
> dinosaurs [that] they forget the rest of the biota. Birds, mammals, and
> amphibians managed to survive, and that tells you that there is something
> wrong."

This is what always bugged me about the impact extinction scenarios. If it
really had that devastating an impact on the entire planet, then why only the
dinosaurs and not all land vertebrates?

Does that mean that none of the dinosaurs would have been sufficiently
sheltered and capable of surviving the aftermath, but birds, mammals and
amphibians could?

~~~
Arnt
Yes. No.

Mammals didn't survive as such. The big ones died, as did many, many other
species. As the paper points out, "mammals surviving the K-T event were
generally rat-sized or smaller".

Generally, there are more small animals than big, I mean more individuals of a
particular species. There are more flies than elephants. If the chance of of
an individual dying in the Big Oven is 99%, greater numbers help the species
survive.

------
marmot777
This deserves an upvote for the title alone. :-)

