Continuity and derivations of life forms between sponge and man.

• 
  Orientation : Inside / outside. First stage of polycellular organism.
• 
  Animation and coordination : Invention of muscle and nervous cells. Mouth and stomach.
• 
  Swimming worm. Bilateral symmetry. Segmentation. First internal organs.
• 
  Primitive Cephalochordata, formation of the spine. Differentiation of internal organs.
• 
  Skull (with eye) and spine is complete. Vertebrata : the nervous system is complete.
• 
  Formation of the Jaw. - Differentiation of fins. Chondrichthyes stage
• 
  Typical fish - Invention of bones and scales, the fins have complex musculation and articulations. The lateral fins will evolve to become limbs.
• 
  The fins evolve to fleshy members. Apparition or differentiation of lungs? First land movements?
• 
  Formation of the neck. Fingers appear - movement and prehension ability.
• 
  Land conquest. Lungs are functional, but the animal is still water-dependent for reproduction. (this one should be a salamander, not a lizard, but the general outlook is OK)
• 
  Dry skin and water-independence of Amniote. (this one should be a lizard, not a salamander, but the general outlook is OK)
• 
  Hair and gestation invention. Primitive mammalia are but insect-eaters "hairy lizards"... this one's cute, isen't it?
• 
  Living in trees, our ancestors gained an opposable thumb and binocular frontal vision.
• 
  (I needed an intermediary picture for smoother transition, so...) Higher monkey - social interaction and communication probably increased at that time. Ability to awkwardly walk on two feet.
• 
  (I needed yet another intermediary picture for smoother transition, sorry) Our nearest cousin - lost its tail, by the way.
• 
  Vertical position frees the brain and the hand.

DescriptionAncestors 2.gif	Evolution line from sponge to man
Date	1 January 2007
Source	Own work
Author	Michelet-密是力 (talk)
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