Developmental basis of limblessness and axial patterning in snakes. Analyses of mitochondrial genomes strongly support a hippopotamus-whale clade. Stanhope, M.J., Madsen, O., Waddell, V.G., Cleven, G.C., de Jong, W.W. and Springer, M.S. 1998. Highly congruent molecular support for a diverse superordinal clade of endemic African mammals. Phylogeny Computer Lab Gagneux, P., Willis, C., Gerloff, U., Tautz, D., Morin, P.A., Boesch, C., Fruth, B., Hohmann, G., Ryder, O.A. and Woodruff, D.S. 1999.
Mitochondrial sequences show diverse evolutionary histories of African homonoids.
Maddison, W.P. 1997. Gene trees in species trees. Paleoecology Colvinaux, P.A. 1978. An ecologists perspective, Chapter 3. Late Cretaceous-Cenozoic history of dediduousness and the terminal Cretaceous event.