MORRISON MAMMALS: PANTOTHERIA 



43 



AA A 



>B 



A* 4Jl 



A 



rom bhate IL^UM. 



^A 



H 



O^TjiJ, 



find this distortion of perspective acting even more strongly in the usual treatment of 

 the Pantotheria. which do resemble the later mammals in many important respects. 

 Passing over the taxonomic history of the group between 1824, when its first member 

 {Antp/iit/icriutn) was described, and 

 1 87 1, one finds that even at the lat- 

 ter date the existence of the group as 

 such was not recognized by Owen. 

 In his classic memoir he grouped 

 the pantotheres with such manifestly 

 extraneous forms as Microlestes 

 {Thomasia), Spalacotherium, and 

 Dromatherium. At that time no ade- 

 quate conception was possible of the 

 truly vast gap between the Jurassic 

 mammals and the Tertiary ones, 

 whether measured in years or in 

 evolutionary progress. It was possi- 

 ble for Owen to hope that bulky 

 "ungulates and carnivores may still 

 be found at Stonesfield or Durdle- 

 stone, or elsewhere.'"^ 



In 1880, Marsh named and de- 

 fined the order Pantotheria, in the 

 following words : 



"With the exception of a very 

 few aberrant forms the known Meso- 

 zoic mammals may be placed in a 

 single order, which may appropri- 

 ately be named Pantotheria. Some 

 of the more important characters of 

 the group would be as follows : 



( 1 ) Cerebral hemispheres smooth. 



(2) Teeth exceeding or equaling 

 the normal number, 44. 



(3) Premolars and molars imper- 

 fectly differentiated. 



(4) Canine teeth with bifid or 

 grooved fangs. 



(5) Rami of lower jaw unanky- 

 losed at symphysis. 



iTiide 



1-niide 



Ant^T, 



K 



Innde 



Outildr 



Fig. 20. Mesozoic mammals. Last lower premolars. A, 

 Atnfhilestes broderipii. B, Priacodon robustus. C, Amphi- 

 don superstes. D, Tinodon bellus. E, Paurodon valens. F, 

 Laolesles eminens. G, Dryolestes priscus. H, Docodon vic- 

 tor. I, Lance didelphodontine. J, Lance pediomyine. K, 

 Lance Pinsectivore. L, Psalodon marshi. M (bottom three 

 drawings), Menisco'essus. Not to scale. 



" That is, elsewhere in the Jurassic. Stonesfield, Oxfordshire, is the locality of the middle Jurassic 

 Stonesfield slate mammalian fauna, and the upper Jurassic mammalian fauna of the Purbeck beds comes 

 from Durdlestone Bay in Dorsetshire. 



