"The further down the CNS you move, from the hind-brain through the medulla into the spinal cord, you descend back into the neuronic past. For example, the junction between T-12 and L-1, is the great zone of transit between the gill-breathing fish and the air-breathing amphibians with their respiratory rib-cages, the very junction where we stand now on the shores of this lagoon, between the Paleozoic and Triassic eras.
Ballard- The Drowned World