GODDIDIT! That’s the only explanation for two completely different animals evolving the same gene. God was pissed off about the creation/evolution debate, so he went back a few thousand years and put the same gene into both dolphins and bats. Then he was like “Mwah! Wait until I create the field of genetics and then nudge some smarmy biochem post-doc in the early 21st century into comparing the DNA of these two animals! That’ll show ‘em.”