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Re: Tyrannosaur scavenging (was DROMAEOSAUR "SICKLE" CLAWS)

Chris Campbell wrote:
> It's more than that,though.  It just wouldn't be efficient to rely
> primarily on scavenging; there's a reason vultures are the only large
> scavengers out there -- they can soar all over creation looking for food
> and it costs them next to nothin in terms on energy expenditure.
> Picture a wolf trying the same thing: do you honestly think it could
> find enough dead stuff to subsist on?  In an environment as complex as
> the Serengeti the _T. rex_ might get away with a fair amount of theft,
> but not enough to survive on.  Hyenas, who probably scavenge more than
> any other large predator, still take down some 60-70% of their own
> food.  They just can't cover enough ground to do things by
> scavenging/theft alone.  Yes, _T. rex_ has a big honking olfactory bulb;
> but it has to get to the kill it's picked up before it's picked clean by
> others, and it has to do this on a regular basis.  Vultures operate by
> finding food fast, getting to it quickly via flight, and scaring off
> other predators via large numbers.  _T. rex_ didn't have any of these
> advantages, andthat sniffer would work just as well for finding food as
> for finding carrion.
> Chris

        If tyrannosaurs developed excellant senses for locating
carcasses, the strength to fight off other carnivores (and perhaps
other tyrannosaurs), and the speed and endurance to get to
carcasses quickly, wouldn't all these adaptations also make it
well suited for active hunting? It all comes down to what is easier:
fighting off other carnivores or subdueing the prey yourself.
If tyrannosaurs were locked in an arms race to out compete each
other for a carcass, there must come a time when the amount of
energy and risk involved in fighting off rivals is more than
would be required to kill a creature yourself. Of course the
large size of tyrannosaurs may have helped them defend their own
kills from other predators rather than being entirely for the benefit
of stealing the meals of others. Perhaps some tyrannosaurs made
a living entirely from scavenging, just as you get the occasional
lion (often a lone bachelor) that will specialize in eating
porcupines or something equally unusual for lions. 
        Then again, Mesozoic ecosystems were so different to any
in living human experience that their intricacies are probably
beyond imagination. Who can really say with any certainty whether
a large carnivore could have lived from scavenging or not, when the
details of its ecosystem are not known?
        Dann Pigdon
        Melbourne, Australia