Why???
ìOld Storyî: fish are living in habitats that dry up, or that run low on food. Those that survive are the ones that can crawl to new ponds.
- Moving on land = natural selection for limbs
ìNew Storyî: Acanthostega and others had fully formed limbs, but probably never left the water.
- Limbs were useful ìafter the factî for moving on land, but they originally had a different function.