RE: Campbell's even crazier than a MANIAC? (archeopteryx climbing)

[Dann Pigdon <dannj@alphalink.com.au>]

Quoting Tim Williams <twilliams_alpha@hotmail.com>:

> Eric Boehm wrote:
> 
> > So my related question is: Is there a fundamental superiority to Mammalian
> quadruped predators that 
> > resulted in them outcompeting the Biped "terror birds" (really the closest
> thing after the KT to a classical
> >  dinosaur), or was it an accident of geographhy?
> 
> 
> Maybe the success of predatory mammals vs predatory birds has more to do with
> teeth, rather than bipedality vs quadrupedality.

My guess is that reproductive strategies may have given the mammals an 
advantage. Birds can try 
to defend a nest, but if they instead choose to run away then their eggs remain 
'sitting ducks'. A 
pregnant sabre-tooth however could run away with it's precious unborn (but not 
un-borne!) cargo 
safely inside it. Once the cubs were born (so no longer borne), a mother could 
bed down with them 
while they were especially vulnerable and produce milk from her own reserves 
for a while, 
reducing the cubs' visibility to predators.

Terror birds would have had to search for food for their hatchlings as soon as 
they'd fully absorbed 
their yolk sacks. If they raised chicks in pairs, then they may have been able 
to have at least one 
parent on guard duty at all times. However if the parent (either male or 
female) raised the chicks 
alone, like emu males do, then foraging for food would have required either 
leaving the chicks 
unguarded for a while, or the chicks to forage with the parent (the latter 
increasing their visibility 
and improving the odds of predators spotting them).

Sabre-tooths may also have been able to excavate den sites for their young to 
hide in once they 
were born, and to run too once they got old enough to be mobile. I suppose 
having a functional set 
of forelimbs capable of digging helps in that respect.

-- 
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Dann Pigdon
GIS / Archaeologist              http://geo_cities.com/dannsdinosaurs
Melbourne, Australia             http://heretichides.soffiles.com
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