 Using shared derived characters, an early attempt in the 1970s used strict parsimony to determine the three long-necked genera ("Chelodina", "Chelus", and "Hydromedusa") were each other's closest relatives.This was accepted for some time, but brought into scrutiny, because the major differences between the genera showed they all appeared to have evolved independently of each other, hinging on the fact that although they had long necks, how they used them and their structures were different.A number of additional data sets were developed that used electrophoresis and nuclear and mtDNA analysis; these all agreed on the independent evolution of the three long-necked clades.