Yes, I understand and believe the asteroid impact die-off theory … the K-T event … see: Wikipedia Entry. But I also believe that dinosaurs might have been seriously stressed by increased gravity for even millions of years before this event … otherwise why was it that only much smaller animals eventually replaced them?
Which takes us to the:
Postulate: the Earths gravity has gotten stronger over the last few hundred million years.
This postulate would totally explain the disappearance of those huge dinosaurs … but not the small ones like the velociraptors. I can only surmise that these smaller ones were totally dependent on their larger brethren for carrion … like today’s vultures … and when they went away, so did most of their smaller cousins.
This of course leaves the difficult question — how did gravity get stronger over hundreds of million years? I have two Lemmae:
Lemma 1: Sentists have speculated that there might be an undiscovered elimentary particle dubbed a “graviton.” I myself have surmised that, after the Big Bang, gravitons attached themselves to matter to create our now-known world. However, excess gravitons (dark matter?) still exist in abundance … and are still increasing matters’ gravity throughout the universe … uniformly.
Lemma 2: Gravity is a measure of acceleration (distance/time^2) … which means that any decrease in the time unit, means that gravity increases exponentially. Science has been trying to discover if the time metric has changed over the millennia … but so far, no dice. (Admittedly, an extremely difficult thing to discern.)
To me, one of these two Lemmae or both, might well be true … thus no more dinosaurs.
STAND UP FOR GRAVITY!