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Re: Why did small dinos become extinct?
john hunt writes:
If you accept the global de-vegetation theory it is possible to postulate a
fast extinction of all large animals (bigger than a cat), everything that
was not an insectivore, as there must have been a bug spike to go with the
Not sure how the crocs made it through though.
No doubt there was an initial glut of carcasses for crocs and small
theropods to scavenge from. Once they were gone (either eaten or rotted
away), the lower metabolism of crocs may have given them an advantage, since
they could have gone longer between meals than a high-performance theropod.
Being able to swim (crocs) or fly (volant theropods) may have also been an
advantage, as either mode of travel would have allowed animals to cross long
distances in search of scarce food. Purely terrestrial animals (non-volant
theropods) may not have been able to travel the necessary distances between
food resources efficiently enough. If you use more energy finding food than
the food itself provides, then you eventually starve.
Then there are questions of genetic bottlenecks. Some modern rodents can
found an entire population based on a single pregnant female, with few
inbreeding problems. Other species suffer far more from inbreeding, and
require a much larger gene pool to remain viable. I suspect those species
susceptible to inbreeding tend to fare poorly during mass extinction events,
while those that can bounce back quickly despite genetic bottlenecks tend to
thrive. In the case of theropods, perhaps only some of the volant varieties
were able to cross large enough distances between isolated pockets of
survival to maintain a necessary level of genetic diversity.
GIS / Archaeologist geo cities.com/dannsdinosaurs
Melbourne, Australia heretichides.soffiles.com