Re: eggs with thin shells

[larrys@zk3.dec.com]

>How about a thick gelatinous secretion from the cloaca during egg-laying,
>that lets the egg dangle in a big droplet of goo or foam, slowly and
>gently drooping down to the ground?  The goo probably would have to
>de-gel-ify and run off, disintegrate or evaporate porously soon after
>laying, to allow air to reach the egg.  Footage of sea turtles dropping
>eggs into their deep sandy pits shows a pretty gooey liquid going along
>with the eggs.

_You've_ been watching _Aliens_!  :)

Actually, this strikes me as particularly "near-fetched".  I do
recall the pictures of sea turtles laying and they do have some
sort of slime that seems to cushion them.

>Perhaps a linear row of eggs would not be crushed by the tail if the
>mother dino `scootched' herself backwards as each egg is laid.  That allows
>the mother to crouch over the eggs already deposited, protecting them
>with her body and forelegs until she was all done.  The forelegs (if long
>enough -- sorry Mrs. Rex!) would be in a good position to cover up the
>trench as she went.

>Alternatively, perhaps a linear row of eggs is consistent with the eggs
>(and their gelatinous goo) sticking to the tail and sliding down along
>the underside to a precision landing!

Again, a very plausible idea, methinks.  Either one would certainly
explain the linear positioning.  I've been wondering about tails, anyway.
Among the dinosaurs, they are universal, and nearly all are large, heavy
and muscular.  Yet outside of dinosaurs and lizards, large tails are
almost unknown - and certainly not very popular in mammals.  Compare an
elephant's tail to an apatosaur's!  In the case of bipedal dinosaurs, this
is not such a mystery, they were counterweights.  But for sauropods and
others, there must have been a very good reason why they stayed so large.

This presents one possible reason that I rather like.  I could see an
apatosaur, for instance, rooting around with it's tail to make the
trench and dripping the slimey eggs into it - the slime not only braking
and cushioning the falls but cushioning the eggs as earth was pulled
over them as well.

I also think the tail served as an active shield against pursuing
predators.  A large, muscular club at the aft end would be an effective
way to keep a t-rex from severing your aft spinal column - or sinking
her jaws into your hip neural cluster.

>Could eggs have slid down one of those protrusions, to a nice soft
>landing?

Sure seems like it.  It may be that the eggs were soft when laid
initially, to pass easier and be a bit more shock-proof, and perhaps
the slime would have become the hardening agent.  If the exact egg
shape varies within a nest insteadof being almost identical but for
size, this guess might be close to the truth - though with so many
eggs smashed, it would be hard to tell.

>What good are the pubic processes structurally anyway?
>Would they have made a good `mounting point' (so to speak :-) for the
>genital organs of both male and female, and have allowed a smaller drop
>height for the eggs?

That's another thing that always bothered me about the tails.  Seems like
they'd get in the way.  Or boy 'rexes must've been very well-hung indeed.
Lends a whole new meaning to the phrase "a terror of tyrannosaurs"...

regards,
Larry Smith