INSECTIVOBE 



Recent 



Pleistocene 



Pliocene 7 



Miocene 19 



Oligocene 30 



Eocene 45 



Cretaceous and 

 Palaeocene 125 



Figure ^6. Probable pedigrees of the various Cetaceans (see also Fig. 27). Geological ages 



are marked on the right ( (>i millions of years ) . Broken lines mean that no fossils are known from 



the period in question. [After data by Slijper. 1936.) 



