According to theories, what was earth’s atmosphere originally like?

Refer to this portion of a dichotomous key to answer the question.1. (a) has a single dorsal fin  ®  5          (b) has a double dorsal fin  ®  25. (a) has a small fin on back near tail  ®  6          (b) has no fin on back near tail  ®  76. (a) has barbs near the mouth  ®  catfish          (b) does not have barbs near the mouth  ®  107. (a) tail is asymmetrical  ®  sturgeon      (b) tail is symmetrical  ®  8what would the result be when identifying a fish with a single dorsal fin, no fin on its back near the tail, and a tail that is asymmetrical? sturgeongo to step 8go tp step 2catfish.mark this and return