Dispersalist Implications of Paraulacodusindicus: A South Asian Rodent of African Affinity

The rodent family Thryonomyidae, especially the middle Miocene Paraulacodus indicus from Pakistan, presents the minimum biogeographic and biostratigraphic conditions required to document intercontinental dispersal. Thryonomyids have a long evolutionary history in Africa, where the closest relatives (congeneric) to P. indicus occur. The Siwalik fossil record of the Indian Subcontinent is sufficient to precisely date the range of P. indicus, and demonstrates the lack of a close relative in that region. A scenario of long distance dispersal from Africa to southern Asia in the middle Miocene best explains the Siwalik occurrence of P. indicus. Paraulacodus indicus is more closely related to P. johanesi and other African middle Miocene species than to the smaller Kochalia from older and coeval Siwalik stratigraphic horizons. We reconstruct two dispersal events of Thryonomyidae from Africa to the Indian Subcontinent, the first prior to 16.3 Ma, and the second about 13 Ma.