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Re: Sauroparental care



--- Graydon <oak@uniserve.com> wrote:
> > On Sun, 21 > 
> News to all those frogs, that.

Frogs hide, disperse, or otherwise protect their eggs.

> There isn't any way to make ~50 2kg eggs a big
> investment to a 20 ton
> parent.  (Unless mating is really, really risky, but
> that's not likely.)
> 
> That hypothetical clutch is 100 kg out of 20,000 kg;
> half a percent of
> body mass for fifty chances to successfully
> reproduce.  Lay eggs at that
> rate once per wet season over a fifty year
> reproductive life and you
> have 2,500 chances.  If _two_ offspring, less than
> one per thousand,
> succeed in reproducing themselves, you're fine, in a
> proper Darwinian
> reproductive sense.
> 
> That looks like sauropods could be as completely
> R-strategist as sea
> turtles.

I am no scientists but I find there are some serious
problems with theorizing sauropods could have done
what sea turtles do.

First of all, there is the depth at which the eggs are
buried and the type of nest.  Sea turtles bury their
eggs a good foot to two feet underground in a habitat
where once the sand is brought back, it is very hard
to tell where the nest is.  Sauropods weren't ones for
delicate work and they didn't have beach sand to dig
in.  Could they really feasibly dig underground nests,
let alone in a colony, and pack the ground down to
where the nest was not noticeable, without crushing
the nest or leaving the area so denuded, full of
footprints and droppings that anything going past
would recognize that the sauropods had been there?  

Secondly, there are the predators.  This is connected
with the sea turtle points above.  As far as I know
the sauropod nests in Argentina appeared to be rather
exposed nests or at least ones that would be
recognizable from the surface.  Even with thousands of
eggs it would be suicide to leave them all in a place
asily accessible to predators.  Sea turtles go to
great lengths to hide their eggs and even then less
than 1% of them survive to adulthood.  This is fine
for sea turtles of course but I don't think the result
would be the same for sauropods.

Thirdly, there is the number of eggs.  The sauropod
clutches were a few dozen at most right?  Sea Turtles,
even the small species, all lay over fifty to over two
hundred eggs per clutch and several cluthes per season
at that.  Thus the glut of hatchlings from saurpods
could not equal that of relatively small sea turtles. 
A bad strategy in a world where every predator large
and small comes to wherever a glut of defenseless
hatchlings are.  Even lions will eat, or attempt to
eat in the case of ostrich eggs, egg if there is an
opportunity.  It would be a simple matter for a large
theropod to dig away at a nest and gulp down the
massive nutrition the eggs would give in a few bites. 
            

Destroying surrounding vegetation could be easily
avoided as well.  Aside from fasting there is the fact
that only a few sauropods from any herd needed to stay
at the nest colony at any one time to protect the
young, just like many modern days animals only leave a
few babysitters.  The rest of the herd could go off
miles away and feed, other individuals switching out
with the babysitters routinely.  

I doubt that baby sauropods traveled with the herd for
many reasons.  However, even merely guarding the eggs
until the young could safely escape into hiding could
very well have been enough.  What I don't beleive is
that they could have ensted in colonies without any
nest protection.  Sea turtles these creatures were
not.   

Happy holidays all!

Jonathan Schmidt