evidence: The Rupununi wetlands represent a feature related to the dissolution of the proto-Berbice paleodrainage. Through most of the Cenozoic, the proto-Berbice flowed along the southern flank of the Pakaraima mountains emptying at the mouth of the modern Berbice River. It included parts of the modern Orinoco, Branco (including the Takutu), Essequibo (including the Rupununi), Berbice, and Courantyne river systems. During the Pliocene and Pleistocene, rivers such as the Cotinga, Uraricoera, Ireng, and Takutu were captured by the Branco River (a tributary of the Negro-Amazon rivers). Perhaps due to continuing head cutting of the Amazon River and/or the fact that the Rupununi savannas occupy a slowly filling depression that in the early Cretaceous formed the paleo-Lake Maracanta, the Rupununi portal was formed (see Lujan and Armbruster, 2011 for review).