Problem: In the Carboniferous period (359 mya), a mass extinction resulted in a loss of 75% of species on earth. This allowed for the chimera lineage to dominate and proliferate, resulting in many new species. For example, there was the emergence of Stethacanthus, which had a truly peculiar anvil-shaped fin on its back, Helicoprion with a spiral buzz saw-like bottom jaw, and Falcatus, in which the males had a long spine jutting out of the back and over the top of the head. This scenario is an example of: In the Carboniferous period (359 mya), a mass extinction resulted in a loss of 75% of species on earth. This allowed for the chimera lineage to dominate and proliferate, resulting in many new species. For example, there was the emergence of Stethacanthus, which had a truly peculiar anvil-shaped fin on its back, Helicoprion with a spiral buzz saw-like bottom jaw, and Falcatus, in which the males had a long spine jutting out of the back and over the top of the head. This scenario is an example of: Mutation