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Re: [humanism-174] Tetrapod anatomy: Backbone back-to-front in early animals

From: sheri p.
Sent on: Monday, January 14, 2013 12:40 PM
That does help, Tim.  I was confused about whether the spine was "spun" around or if it was what you said; reversed from head to tail.  I just couldn't picture it and their pics didn't help.  But, your second paragraph definitely made me see what you are talking about with the "pushers and pullers.  That makes sense!

Thanks! :)



On Mon, Jan 14, 2013 at 12:28 PM, Tim Campbell <[address removed]> wrote:
I need to read the corresponding papers and perhaps see some pics of comparative anatomy, but I am guessing that some of the structures in our spines that in modern four-limbed backbone animals face the butt end, in early animals faced forward, with mnore emphasis or concentration on the front half of their anatomy .  Keep in mind that tetrapods developed lung-like apparatus, but still lived in the sea. They shared a common ancestor with fish, but they were not strictly fish, though they lived in the sea.  Apparently, this orientation of specific structures in their spines somehow aided in their transition from sea animal to sea-land to land. 
 
One possibility is that these early four-limbed animals concentrated their musculature in their front limbs and thus pulled themselves along, whereas most modern four-limbed animals have more of their musculature and strength in their hindquarters, thus being more "pushers" than "pullers". 
 
But I am making some assumptions here based only on reading what is after all a basic summary of the actual scientific papers!  Hope this helps a little bit!
 
Tim Campbell
 
In a message dated 1/14/[masked]:56:07 A.M. Eastern Standard Time, [address removed] writes:
http://www.bbc.co.uk/news/science-environment-20987289

Okay - I am being honest here and feel stupid, but I don't know what exactly they are saying here.  I am confused.

Any help in explaining this would be great.

Thanks,
Sheri





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