^Muizon, C.de and Cifelli, R.L. The "condylarths" (archaic Ungulata, Mammalia) from the early Paleocene of Tiupampa (Bolivia): implications on the origin of the South American ungulates. Geodiversitas. 2000, 22 (1): 47–150.
^Hunter, J.P. and Janis, C.M. Spiny Norman in the Garden of Eden? Dispersal and early biogeography of Placentalia. Journal of Mammalian Evolution. 2006, 13 (2): 89–123.
^Shockey, B.J., and Anaya, F. Pyrotherium macfaddeni, sp. nov. (late Oligocene, Bolivia) and the pedal morphology of pyrotheres. Journal of Vertebrate Paleontology. 2004, 24 (2): 481–488.