Joe LeMonnier 



Suborder 



Family Tree of the Order Carnivora 



F e I i f o r m i a Caniformia 



Family FELIDAE 

 Common name (Cats) 



HYAENIDAE VIVERRIDAE 

 (Hyenas) (Civets) 



CANIDAE AlVIPHiCYONIDAE URSIDAE 



(Dogs) (Bear-dogs) (Bears) 



Extinct 



■PINNIPEDS' PI50CY0NIDAE MUSTELIDAE 



(Sea lions, (Raccoons) (Weasels, Skunks, 



Walruses, Otters) 

 Seals) 



dhole, the most hypercamivorous living 

 canids, have the most catlike teeth. Similar 

 teeth are found in some extinct amphicy- 

 onids and several groups of fossil canids. 

 This phenomenon, called paiallel evolu- 

 tion, is widespread among mammals in 



Lion 



general. It occurs when closely related 

 groups of mammals follow similar adap- 

 tive paths. 



A related phenomenon is convergent 

 evolution, in which distantly related spe- 

 cies achieve similar adaptations and come 



Carnassial (Premoiar) 

 Premolars 



hcisor 



Carnassial (Malar) 



Premolars 



Carbines 



Wolf 



Molars 



Carnassial (Premolar) 

 Premolars 



Incisors 



Molars - 

 Talonid • 

 Carnassial (Molar)' 



Premolars 



Canines 

 Incisor 



to resemble each other superficially. For 

 example, different skeletal parts of the 

 forelimb were modified in bats, birds, and 

 pterosaurs to produce the same adaptation, 

 flight. Similarly, some mammals outside 

 the order Carnivora have evolved teeth 

 that resemble camassials. These include 

 the Tasmanian devil, which is a primarily 

 carnivorous marsupial, and the extinct cre- 

 odonts, placental mammals usually re- 

 garded as distant relatives of the Car- 

 nivora. In these relatively primitive 

 animals, all the molars have a camassial- 

 like form, functioning together like pink- 

 ing shears. Similar teeth also characterize 

 early members of the order Insectivora. In 

 one insectivore. the hedgehog, the same 

 teeth as in true camivores have become 

 specialized camassials — the upper last 

 premolar and lower first molar. This ap- 

 pears to be an unusual case of convergent 

 evolution, in which the same structures are 

 involved among animals only distantly re- 

 lated to the Carnivora. 



A comparison of the skulls of a lion 



and a wolf reveals the cat family's 



extreme adaptation to carnivory. 



The lion lacks crushing teeth; its 



only lower molar is the meat- 

 shearing carnassial. Its sole upper 

 molar is a tiny, hladelike tooth, here 

 hidden behind the upper carnassial. 

 The wolf retains molars for 

 crushing, and even its lower 

 carnassial has a shelflike section, 

 the talonid. In this view of both 

 skulls, the canines and larger 

 incisors hide the smaller incisors. 



Illustration by Ed Heck 



76 Natural History 4/94 



