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Re: Dino sex and therm tally rant

On Tue, 15 Jul 1997 09:54:00 +1000 Dann Pigdon <dannj@alphalink.com.au>
>A recent posting (not in any way a "discussion") made reference to
>dinosaur pornography. This has brought up an issue I have always felt
>has been neglected: dinosaur mating.

Hooray! Tyrannosaurus sex! ;-)

>Dinosaur cloacas are often mentioned, but is there any actual evidence
>that dinosaurs had a bird-like cloaca? If I remember correctly birds
>do not have a penis-like structure but instead rely on a "cloacal

Most birds do mate through cloacal "kissing."  But some birds _do_ have a
penis or penis-like structure: ratites (emus, ostriches, cassowaries,
rheas), certain ducks, geese, gallinaceous (chicken-like) birds and S.
American tinamous have well-developed penes, some resembling those of

>(snip)... Being able to "squat" backwards and take some of the
>weight on the tail may have allowed sauropods to lay eggs without the
>need to let them drop from a great height (although giraffe babies
>drop seven feet to the ground and they seem to do okay). 

Giraffe babies are not in a shelled egg, and they come out front feet
first!  The fall breaks the umbilical cord and may be an adaptive way to
stimulate the baby to get to its feet quickly (within 15 minutes) or it
ends up as lion lunch.

>to the "sauropod squat" would be to have rubbery egg shells (the
>sea turtle approach),

Do you mean have a rubbery egg so that you can release it from a height
and it can bounce unharmed?  Remember that sea turtles lay their eggs in
sand, and if the eggs drop down, they are hitting something soft anyway. 
Wouldn't a nesting dinosaur have something soft lining the nest whether
the eggs were soft or not?

> although clearly those eggs that have been
>interpreted as being sauropod were hard shelled, which may rule this
>line of inquiry out.

The fact that all dinosaur eggs found so far are even fossils tends to
rule out the rubbery shell idea.  A rubbery egg like that of today's
reptiles would fossilize rarely if at all.

>All conjecture of course, with more questions than answers, but then
>that seems to characterise much of palaeontology. Does anyone else
>have any ideas on the subject? Any scientific discussion, however
>conjectural, must be better than the recent "what's on your monitor"
>discussion or the endo-ecto-mesothermy tally.

Amen to that. Regarding the recent "therm" tally, I think people are too
much influenced by the media taking and reporting polls on just about
every topic.  Though news and politics seem to revolve around polls, due
to the normal human curiosity about what other people are thinking,
science should not operate in that way.  Despite what the media may
think, or what they want the public to think, a scientific hypothesis is
not tested by taking a poll of scientists to see who agrees with it.  The
strength of a hypothesis is determined by the amount of data that
supports it.  Period.

This is a discussion group, not a peer reviewed journal, and I have no
objection to polls per se.  But the "therm" tally is just fluff, and has
no scientific value, other than indicating who stands where.  I don't
have objection to fun fluff once in a while either, to break things up a
bit.  But when these polls and tallies give those new to this list (and
to science and paleontology) the impression that this is how science is
done, I have to protest and wince.  

Enough already about what's on your monitor and how warm (or cold)
dinosaurs were (are).  Let's just agree that dinosaurs are _way cool_.

Judy Molnar
Education Associate, Virginia Living Museum
All questions are valid; all answers are tentative.