In 2002, American geneticist Beth Shapiro and colleagues analysed the DNA of the dodo and the Rodrigues solitaire for the first time. Comparison of mitochondrial cytochrome "b" and 12S rRNA sequences isolated from the femur of a Rodrigues solitaire and the tarsal of a dodo confirmed their close relationship and their placement within the Columbidae. The genetic evidence was interpreted as showing the Southeast Asian Nicobar pigeon ("Caloenas nicobarica") to be their closest living relative, followed by the crowned pigeons ("Goura") of New Guinea, and the superficially dodo-like tooth-billed pigeon ("Didunculus strigirostris") from Samoa. This clade consists of generally ground-dwelling island endemic pigeons. The following cladogram shows the closest relationships of the dodo and the Rodrigues solitaire within Columbidae, based on Shapiro et al., 2002: