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RE: The extinction of small dinosaurs
Re: HP Edels post:
> I've mentioned the ability to hibernate as a possible key to survival
> through the K-T in many of my posts on extinction in the past.
Mammals that don't hibernate cannot be induced to. Most mammals in
"equable" climates don't hibernate. Birds don't hibernate. Dinosaurs
might have hibernated.
Re HP Gay's post:
> Remember that the extinction didn't just effect dinosaurs. Most marine
> was badly hurt...
Most marine life except...wait for it...fish?
> as were other forms of terrestrial life.
Except for...wait for it...mammals, snakes, lizards, crocs, birds,
turtles, insects, molluscs, amphibians, flowering plants, gymnosperms,
ferns, fungi, bacteria?
> ...its a question of "what animals overall were affected and why?"
And, don't forget, "if". Extinctions attributed may not belong--birds,
> I am no expert on plants by
> means, but I would think that those groups most successful in coming
> the extinction were either lucky in placement (for some reason
> effects weren't as bad, thinner dust layer), or have long germination
> cycles/seeds can remain dormant until conditions are right (I know this
> the case for some types of conifers).
Circular...it must have happened so whatever happened, happened.
> As for animals, you ask, why did small non-avian dinosaurs die out?
> animals with high metabolisms need to eat a lot, simply because its
> generally energy inefficient to be small and high energy.
Most of the creatures that "survived" were small. Their lack of
"efficiency" didn't hurt them. "Efficiency" needs definition, I
think. Some might say a lumbering behemoth is very inefficient in many
respects. In terms of efficiency with energy, a small creature may have
access to a greater range of food, grubs eating leaf litter, for
example. In the overall equation, energy in--relative to energy
harvested--may not be an important factor. At the very least, just saying
so is not convincing.
> Surface to
> ratios allow a high portion of heat to escape, and might
> digestion of food, meaning you'll need to fill up that stomach sooner.
> That's why if you have a pet rat/ferret/rabbit, etc., you'll see it
> eating a
> lot: it needs to! I would imagine that the same was true for pre-K/T
> dinosaurs, that they would need to eat a lot.
This is contra my experience. I have a dog and a cat that sleep most the
live-long day...were small dinos more like them or gnawing furball rats?
> And dromeosaurs weren't
> exactly small, but I think of them kinda like turkey-sized, and if you
> at your pet dog, it seems to either be eating or sleeping.
What else is there? They don't have to study for exams. And mine has no
> What does all this rambling mean? Well, by removing most
> plants from the biosphere...
>...plus turning most non-saline standing
> bodies into acidified lakes/ponds/etc...
...in which sensitive frogs could thrive.
> through the effects of acid rain from the debris
> cloud (that which wasn't evaporated/boiled off during the initial
> temperature spike)...
...which no one has any evidence for, or has ever observed. I'm not
saying such things didn't happen...I'm saying we mustn't get too carried
away with favored hypotheses even if they are popular.
> most herbivorous dinosaurs, large and small, will
> out fairly shortly. Of course, lots of the predatory/omnivorous animals
> have a field day, with the carrion, which would accumulate starting
> immediately, and probably peek a week or two later, after most
> had died. Then, of course, the carnivorous/omnivorous animals would be
> to feast on their compatriots for a while, but remember, its been
> that the dust lingered for months. I find it unlikely that a population
> composed entirely of relatively rare carnivores to be able to survive
> off of
> carrion from other carnivores for even a week. There simply wouldn't be
> enough food in the ecosystem to support them.
Total speculation...may or may not be true.
> So, what about what did survive, terrestrially, then? Well, mammals
> not all of them, of course), crocodiles, turtles, amphibians, snakes,
> lizards, and avians. Pretty odd grouping of metabolisms, and ecosystem
> niches. But all modern representatives of these groups have something in
> common; the ability to go into torpor (similar to hibernation).
> can go at least 9 months without food. Amphibians can even be frozen
> and have all their vital functions cease, and still be unfrozen months
> later and be perfectly fine.
All frogs? Or just the species from unequable climates that have adapted
over time to do this?
> Birds and _some_ mammals both have the
> slow down their metabolisms (look at bears, for instance, as a famous
> example), and lizards, snakes, and turtles can also subsist in lower
> normal metabolisms for extended periods, if the temperature and food
> is low.
Look, all animals species _but_ dinosaurs survived! What evidence is
there to suggest that the above strategies were not also shared by some
dinosaur species? Also, what evidence is there that suggest _only_
members of species that hibernated survived...I think this is a big
stretch. Again, mammals that don't hibernate cannot be induced to.
> That is what I see as the common denominator for all the surviving
> vertebrate groups: torpor. So why did small non-avian dinosaurs go
> extinct? Well, I would say it was likely they couldn't go into torpor,
How do you know this?
> They succumbed to starvation and the
> aftereffects of the bolide impact. I roundly reject the "disease as
> mega-killer" hypothesis, because it would be equivalent to a disease
> that killed all mammals.
Ecology is a discipline of humbling complexity. The elimination of one
hypothesis (I also reject the disease hypo) doesn't validate the favored
hypothesis. There are others. For example, it is quite possible that
behavioral strategies of birds assisted in knocking off small non-avian
dinosaurs; just as it is possible that neornitines outcompeted
enantiornithines. There are predictions taht are in the process of being
tested. Example: was there or wasn't there a bottleneck in bird species
at the K/T. You would say there was, I would say there was not. I'm not
saying this would settle the issue entirely, but it's an important piece
evidence to plug into the puzzle. At least it's evidence.