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Re: pineal gland notes (large body mass)
Drawbacks of large body size when the going gets rough:
1) High trophic position. Large theropods, for example, were at the
very top of any food chain you might want to construct. This has
immediate effects (e.g., concentration of toxins) as well as indirect
effects due to the loss of energy going up the food chain, namely,
2) Smaller slice of the energy "pie," translating into lower total
body mass, translating into lower population sizes, translating into
greater risk of extinction for stochastic reasons. Note that smaller
population sizes are a side-effect of large body size even if you get
an EVEN share of the pie, just because each big dinosaur needs more
energy. Here's an example of stochasticity: if there are ten
dinosaurs on an island, a disaster occurs, and the chance of dying
immediately goes to 50%, there is a fairly large chance that all the
dinosaurs (or at least all the ones of one sex or another) will die.
But if there are 100 dinosaurs that chance is much, much, much lower.
3) Lower intrinsic rate of population increase. This is familiar to
everyone: if you wipe out 99% of the little tiny roaches in an
apartment, it will take them no time at all to recover to "normal"
population sizes before the next catastrophe occurs. If you do this
to a population of dinosaurs, it could take hundreds or thousands of
years to recover EVEN if the environment is temporarily "friendly."
If the K-T was marked by waves of environmental disturbance (say,
wildfires and then a collapse of the food chain and then a sudden
climate change due to changes in ocean circulation patterns, not
necessarily in that order and surely involving many other things),
little guys like birds may have had time to build back their
populations inbetween "rounds" of disturbance, and dinosaurs may not
There's more to this, but there's a LOT more of my thesis to get
written in the next 72 hours (thank god I write fast), so enough for