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Egg sizes



Davor Vrcibradic wrote:
> 
> Davor Vrcibradic
> 
>         What size were the largest dinosaur eggs ever found and where were 
> they
> unearthed (I know that the eggs attributed to Hypselosaurus no longer hold
> the record of size)?   Is there any hint of which species laid them?    And
> how big would possibly be the eggs of giant sauropods such as Brachiosaurus
> and Antarctosaurus?    Is it possible that they were live-bearing (once they
> would, otherwise, have to lay eggs that would be above the size limit to
> which a reptilian egg can possibly get)?

The largest dinosaur eggs I have seen are Approximately 45cm high, and
about 13cm in diameter, (These numbers are approximate, as they are only
from memory.) They seem to be laid in pairs, and are from Mongolia, like
so many of the eggs we're now being introduced to. Guesses on who laid
'em run variously from Tarbosaurus bataar, to Therizinosaurs.

About a year and a half ago, Brian Cooley with TMP did a reconstruction
which made the cover of National Geographic. It was based on a similar
egg which had an embryo in it. Based on his study, and that of several
others, he showed it as a large Therizinosaur. It's not clear whether
this animal is a prosauropod or an ornithomimid, but it had long arms,
and long straight claws on the manus.

But what about sauropods? Well, we believe they had roughly spherical
eggs, (of which there are many different types known.) Embryonic
Camarasaur material led Brooks Britt and Bruce Naylor to estimate an egg
size of about 24cm dia. While smaller than the largest know bird egg,
(34cm high x 24cm dia from Aepyornis,) this is still a big egg.

Eggs from Argentina attributable to titanosaurids are typically 11.5cm
in dia, although I have seen some as large as 17cm. They look like
cantaloupes! So did larger sauropods have larger eggs? Probably, but not
necessarily. Kiwis have an enormous egg relative to their body size It
looks as if eggs tend to get bigger as a species gets bigger, but they
don't get smaller so easily. What happens is that dwarf species wind up
with ridiculously large eggs.

As for live birth, it has been suggested in the literature, but there is
no direct evidence for it in dinosaurs. With so many new egg forms
turning up these days, it looks like eggs were the favored method of
delivery.

And Brachiosaurus and Antarctosaurus? Who knows. We just have to wait
for new material to turn up, or be noticed in the collections.

William Monteleone