Look at how the mouths evolve. The bottom middle looks sorrta like how my Naucean evolved. With little tenticles that turned into limbs. Very cool!!
I read somewhere that this was how some limbs evolved, from food manipulators moving back into general manipulators.
I had read that, too... but then I saw some diagrams that showed fish fins developing from a fold along the sides of their bodies... stingrays just kept enlarging that fold, while other fish split it into parts and each part became a fin.
Then I read that the same gene that creates spider legs creates insect mouthparts, so the mouthpart theory makes sense (a swimming arthropod just wiggles its body to move, but needs parts to catch food.
So I think they're both right, and different lines got legs in different ways. The nauceans seem to have utilized both methods, evolving manipulative mouth parts AND locomotive limbs.
