[4] However, a more recent genetic analysis of mtDNA has found that they are actually most closely related to the lineage containing Centrochelys and Geochelone.

[4] This crossing was made possible by their ability to float with their heads up and to survive up to six months without food or water.

The now-extinct West Indian radiation is thought to group with the Chaco and Galapagos tortoises but is significantly basal to both, and was a rather evolutionary distinct lineage, having diverged well before any of the modern species in the genus did and only 7 mya after the divergence of Chelonoidis from African tortoises.

C. carbonarius and C. denticulatus are presently found on some of the Lesser Antillean islands, but the provenance of these individuals is unknown, and they could have been introduced by Amerindians during pre-Columbian times.

[6][8] A 2017 study found that some of these species such as those from Hispaniola were specialists adapted to dry, open habitats such as Hispaniolan dry forests and had a major role in shaping them; following a decrease in the extent of these ecosystems after the end of the Pleistocene, these tortoises were restricted to refugia habitats up until their extinction.