Tectonic plates explain much of the diversity seen at given locations on the planet, but some species do disperse over water or land to colonize new environments. India, Madagascar, and the Seychelles Islands were one land mass, the Indigascar continent in the late Cretaceous, but it broke into pieces some time in the early Tertiary, which partially explains the shared fauna of these three locations. Now Townsend et al. have used a dated molecular phylogeny of the chameleons to demonstrate that these usually arboreal and terrestrial lizards dispersed over water from Africa to the Seychelles about 38.4 million years ago. Today, chameleons are more or less restricted to Eastern Hemisphere fragments of Gondwanaland and a single species of chameleon (Calumma tigris) is known from the three largest granitic islands in the Seychelles. It has been placed in the genus Calumma which is otherwise known only from Madagascar. The phylogeny produced by Townsend et al. recovered the African Leaf Chameleons (Rieppeleon) as the sister to the Seychelles Chameleon, requiring that it be placed in a separate genus because it is distinct from the Madagascaran Calumma lineage. The new genus is Archaius, and it shared an ancestor with Rieppeleon sometime in the Oligocene-Eocene after the break-up of the Indigascar continent, implying over water dispersal. The graphic below shows the current distribution of the African Leaf Chameleons, a member of the genus Rieppeleon, and the location of the Seychelles in relation to Madagascar and Africa.
Townsend, T. M., K. A. Tolley, F. Glaw, W. Böhme and M. Vences. 2010. Eastward from Africa: palaeocurrent-mediated chameleon dispersal to the Seychelles islands. Biological Letters. doi:10.1098/rsbl.2010.0701
