Re: Somerset Plesiosaur

[Colin McHenry <cmchenry@westserv.net.au>]

Michael Lovejoy wrote:

> Dan Varner wrote:
> http://news.bbc.co.uk/1/hi/england/somerset/3603507.stm
>
> Talk about Macrocephalus! the skull looks to be wider than the torso. Is it
> possible that this thing's juvenile? (do we even know if juvenile plesios
> had relatively larger heads?)
>
> Regards,
> Michael Lovejoy
>
>  

Yes, it certainly reminds me of P. macrocephalus...  Most vertebrates 
have larger heads when juvenile, so it's not unreasonable to suppose 
that plesiosaurs did as well.  If this is a juvenile, then it is 
probably a young Rhomaleosauus - like thing?

However, 1.5 metres long is very large for a juvenile reptile to be 
displaying such 'un-adult' proportions.  By the time a crocodile or 
turtle is that sort of size, it has essentialy the same proportions as 
the adults, and has had for quite some time.  The only time that crocs 
and turtles show such 'juvenile' body proportions  is when they're just 
out of the egg.

So the thought's just occurred to me....if this thing is a young version 
of some Liassic rhomaleosaur, then could it constitute very suggestive 
(although indirect) evidence for live birth?.  The logic being that to 
see juvenile proportions it would have to be very young - and to be so 
young and so large, it would have been way too large to have hatched 
from an egg and would necessarily have been born live. And what a baby - 
1.5 metres is a pretty significant fraction of a (guessing) 5 metre 
mother pliosaur!

Live birth in plesiosars? who would have thought it.....

Cheers

Colin