CSIR NET Dec 2015 Q44: Paleontology & Stratigraphy
Vertebrate evolutionary history proceeds through a well-established ascending (oldest-to-youngest) sequence of major class-level appearances in the fossil record: fishes (earliest, Ordovician-Silurian) preceded amphibians (Devonian), which preceded reptiles (Carboniferous), which preceded mammals (Triassic).
The correct ascending order of first appearance in geological history is: fishes (earliest vertebrates), followed by amphibians (first tetrapods to colonize land), followed by reptiles...
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