580 PLACENTAL MAMMALS xxi. 9 



largely preserved, the Insectivora themselves and the Chiroptera (bats), 

 the Primates and the Edentata (sloths, ant-eaters, and armadilloes), 

 all of which can be easily and directly derived from the insectivores. 

 Here also probably belong the scaly ant-eater, Manis (Pholidota), 

 and the extinct *Taeniodontia and *Tillodonta, which survived only 

 for a short time and of which little is known and they will not be 

 mentioned further. The Rodentia and the rabbits and hares (Lago- 

 morpha) are often also considered to belong here, but they appear 

 fully developed in the Eocene and must have diverged very early and 

 are therefore placed alone in a separate cohort Glires. Similarly the 

 whales (Cetacea) have certainly been distinct since the Eocene. Their 

 affinities are quite obscure, and they are classed as a separate cohort 

 named by Linnaeus Mutica (most inappropriately since they com- 

 municate by sounds). 



All the remaining mammals show signs of a common origin and 

 Simpson suggests grouping them together as a cohort Ferungulata. 

 It has long been realized that the hoofed animals include two distinct 

 types, those with an uneven number of toes, Perissodactyla, and those 

 with even toes, Artiodactyla. The former can be derived from the 

 Palaeocene and Eocene animals known as *Condylarthra. The Carni- 

 vora seem at first sight to have no similarity to either of the ungulate 

 types, but it has been suspected for some time that the ancestral Carni- 

 vora, the *Creodonta, resembled the earliest artiodactyls. Further study 

 has shown that creodonts and condylarths are often so alike as to be 

 hardly separable (they are also very like Insectivora). Simpson's sug- 

 gested cohort Ferungulata recognizes the existence of this common 

 creodont-condylarth stock, perhaps in early Palaeocene times. The 

 cohort may then conveniently be subdivided into five superorders, 

 Ferae for the Carnivora, Protungulata ( = 'first ungulates') for the con- 

 dylarths, the extinct South American ungulates (*Liptopterna and 

 # Notoungulata), the obscure *Astrapotheria and Tubulidentata 

 (Orycteropus, the Cape ant-eater). The third superorder Paenungulata 

 ( = 'near ungulates') includes the elephants (Proboscidea), hyraxes 

 (Hyracoidea), and sea cows (Sirenia), as well as the extinct *Panto- 

 donta, # Dinocerata, # Pyrotheria, and *Embrithopoda. The fourth 

 superorder Perissodactyla is then made to include only the horses, 

 tapirs, and rhinoceroses; and the fifth superorder Artiodactyla the 

 pigs, camels, and ruminants. This system gives us a means of group- 

 ing that is phylogenetically reasonably accurate and also conveniently 

 close to the usually accepted uses of familiar names. 



