> develop armored plates to defend against predators
> innervate scales to detect touch & therefore early detection to predators
> realize the scales around the mouth help scrape algae off rocks better
> develop specialized rough teeth around the mouth to do so even better
> develop jaw
> lose armored plates
> move to land
> “it’s hot out, I want a cold sweet treat”
> bite down
> ah
(Image related)
[Image description: In the first picture, a scientific illustration of two ancient armored fish, from the species Astraspis. In the second, an evolutionary tree; At the bottom an example stem gnathosome Lophosteus develops down two branches. Some evolve into chondricthyans like sharks. The others evolve down a lineage with several progressive steps towards teeth before dividing into sarcopterygians (the ancestors to tetrapods, depicted here with an alligator) and actinoptreygians (the ancestors to teleosts, depicted here with an anglerfish). End Image description.]
























