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Re: Prognathodon (Mosasauridae) had shark-like hypocercal tail fin

It's interesting that several reptile lineages with shark-like tails 
(ichthyosaurs, mosasaurs, ocean 
crocs) all seemed to have kinked the caudal bones downward to reinforce the 
lower lobe of the fin, 
whereas sharks with asymmetrical tail lobes seem to all continue the caudals 
into the upper lobe.

Was this just coincidence (an evolutionary toss of the coin), or could it have 
something to do with 
different buoyancy issues (lungs verses liver)? Does an asymmetrical tail 
subtly change the pitch of 
the animal while it swims, with a dominant upper lobe compensating in one 
direction and a 
dominant lower lobe compensating in another?

On Wed, Sep 11th, 2013 at 1:27 AM, Ben Creisler <bcreisler@gmail.com> wrote:

> From: Ben Creisler
> bcreisler@gmail.com
> A new paper in Nature Communications:
> Johan Lindgren, Hani F. Kaddumi & Michael J. Polcyn (2013)
> Soft tissue preservation in a fossil marine lizard with a bilobed tail fin.
> Nature Communications 4, Article number: 2423
> doi:10.1038/ncomms3423
> http://www.nature.com/ncomms/2013/130910/ncomms3423/full/ncomms3423.html


Dann Pigdon
Spatial Data Analyst               Australian Dinosaurs
Melbourne, Australia               http://home.alphalink.com.au/~dannj