16 



EVOLUTION OF MAMMALIAN MOLAR TEETH 



2 



o 



c 



o 

 O 



CO 

 CD 



O 



c3 



4^> 



CD 



o 



O 



O 



Super-order: NOTUNGULATA (Both) Scott (South American 



Ungulates) (p. 189.) 



Order I. *Toxodontia (Owen) Scott 

 Sub-order 1. *Toxodontia Scott 

 Examples 

 Toxodon 

 Nesodon 



Sub-order 2. *Typotheria Zittel 

 Examples 



Pachyrucos 



Icochilns 



Typotherium 

 Sub-order 3. * H o m a 1 o d o t h e r i a Scott 



Homcdodon totherium 



Order II. * Astrapotheria (Ameghino) 

 Astrapotherium 



Order III. *Litopterna Ameghino (p. 189.) 

 Proterotherium 

 Macrauchenia 



Order: Pyrotheria Ameghino (short-footed South American 



Ungulates) 

 Pyroiherium 



Order: * Zeuglodontia Van Beneden (p. 191.) 



Examples 

 Protocetus 

 Zeuglodon 



Order: Odontoceti Gray (toothed whales) (p. 190.) 

 Squalodonts (Squalodontida?) 

 Fluviatile dolphins (Platanistidse) 

 Dolphins (Delphinid^e) 



Belugas ) /-rx -i i i \ 



& . . I (Delphmapteridae) 



Narwhals J 



Beaked whales (Ziphiidse) 



Sperm whales (Physeteridse) 



Order : Mystacoceti Gray 



Whalebone whales (Balsenidae) 

 Plight whales (Balccna) 

 Humpbacked whales (Megaptera) 

 Finbacked whales (Balcenoptera) 



* Extinct. 



