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What you saw was a situation that is very common in crocodilians. The extraction of calcium from the shell makes the connection between the calcite crystals and the fibrous membrane very fragile and in well developed eggs (crocs and birds) whole sections of shells can come away at external pipping to reveal the soft fibrous membranes below. The croc then pushes its way through the membrane and literally walks out of the shell. This would give the impression of a soft-shelled egg.
I have David Attenborough's works on DVD - which was the one you saw and I'll look at it.
There are no soft-shelled crocodilian eggs - I spent 2 years of my life studying development in crocodilians.
Subject: Re: [Palaeoology] Croc eggs sometimes soft
YeahButNoButYeahButNoBut....
Thanks for that, Charles. Well, now I really don't know what's happening, because I was so shocked I stayed up to watch it all over again on the "+1" channel, and checked it really was a little croc emerging and not some lizard thing, and it really really was a croc. There's no mistaking the head sometimes. Actually, I'd say it was almost certainly not an alligator, to my eye.
FACT: Either I am going mad or at least one species does emerge from soft shells!
I suppose the next stops are Sir David, who has always been kind enough to reply to me in the past, though I've never actually got anywhere with my enqury, or London Zoo. Or whoever has been present when every species of the group has hatched.
> Crocodilian eggs are hard at oviposition having been > calcified en masse in the oviduct. Attenborough got > it wrong (not often but it does happen). I have > worked on and hatched alligator eggs and they are as > hard as porcelain! This is true for ALL crocodilian > eggs. > > > ----- Original Message ----- > From: John Jackson > To: Palaeoology@yahoogroups.co.uk > Sent: Wednesday, May 23, 2007 12:55 PM > Subject: [Palaeoology] Croc eggs sometimes soft > > > Last night I saw (again) an old David Attenborough > program called "Living with dinosaurs", a dreadful > name since it was about crocs, chelonians and > large > lizards, but it did show absolutely unambiguously, > a > crocodylian hatching from a soft-shelled egg. > Attenborough even talked in terms of the mother > helping them hatch out of their leathery eggs. > > Also, as the croc mother was laying the eggs, they > did > seem to be fairly soft, though this was much > harder to > be certain of. They were dropped an inch or two > onto > each other without causing any damage or even > noise. > > I've repeatedly seen it claimed that all crocs lay > hard shelled eggs, and every croc egg I've seen > (on > TV) away from the nest was hard. Can someone > confirm > that they are soft when laid, harden up after that > and > then become soft again before hatching, and that > this > is what happens with all modern crocodylian eggs? > > > __________________________________________________________You > snooze, you lose. Get messages ASAP with AutoCheck > in the all-new Yahoo! Mail Beta. > > http://advision.webevents.yahoo.com/mailbeta/newmail_html.html > > >
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