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Animals Transition to Land

Recently, paleontologists have been making discoveries about how sea animals made the transition to land.  The animal depicted below is representative of these new discoveries.   This animal lived in shallow seas approx 300 million years ago.  It appears ready to transition to land as it has toes (8 of them).

Acanthostega gunnari fossil.jpg              The drawing on the left is constructed from recent fossil evidence and represent animals that lived in shallow seas over 300 million years ago.  These seas were actually drying up into huge swamps.  
            The water was so shallow that animals started to walk along the bottom, as well as swimming.   Acanthostega has the large tail for propulsion through the water AND what can be seen as 8 distinct toes that would be useful for walking along the bottom.

            The bones on the left depict a fin of a species related to Acanthostega.   Notice that the bones create the framework for "fingers" that enhance the animals capability for walking along the bottom.
            Both these species have 8 digits, and were no doubt precursors  to early amphibians which are reported to have had 8 digits. 
            How and when 5 digits came into being is a mystery yet to be solved.              I believe that this fossil suggests a possible 'evolutionary' scenario.
The bone labeled "i" by genetic mutation (or some other genetic mechanism to be discovered) fused to the bone labeled "R".
            A gap between the digits rooted to the R bone and the digits rooted to the H bone is created by the fusion.  
            Also the number of digits is reduced. Possibly 4 digits coming out of the UL bone and 1 larger digit out of R.  Or possibly some other             changes which caused a final figuration of 5 digits with a gap between 4 digits and the larger 5th digit.
            This gap enabled the animal to perform grasping which created some slight survival advantage.  Over time the brain of the animal             learned to control the digits and take advantage for the grasping possibility. This adaptive change found its way into the primate class.
            Soon after the opposable thumb came into existence by the interaction of the digits and the control circuitry  in the brain -             the primate became a user of tools leading to our current situation.  

 Sauripterus.jpgSauripterus taylori fin bones


Native American rendition of a creature with strange properties suggestive of transition from sea to land.   

This ceramic inlay I bought in the South West and never knew quite what to make of it.

Now I have a theory.  The large tail is for propulsion in water.  The 4 fins have turned into digits useful for locomotion along the ground - no opposable digit would be required at this stage. The horn on the mouth would be used by the animal to announce itself on its transition to land - the artists fantasy.

This theory is of course very speculative, however on first glance I thought this was a strange sea creature that was somehow important to life.. and the match up with the fossil record really is amazing.. I credit the Native American naturalist intuition for the strength of this correlation with the fossil record.  




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