This painting depicts the relationship of two of the great orders of South American fish. The Characiformes, which include the piranhas and tetras, and the Siluriformes, or catfish. Since first appearing in the Cretaceous, both groups have evolved side by side, while tending to exploit different niches. The Characiformes have tended to evolve in and toward the light, the Siluriformes have tended to evolve in and toward the darkness.
fishes, Characiformes, Siluriformes, paleontology, South America