MESOZOIC MAMMALS 



xix. 7 ivi£,t>uz,ui^ iMAiviiviAJua 547 



quite unlike anything found on the dentary of therian mammals. This 

 is presumed to have contained the articular and perhaps other bones, 

 fragments of which can be seen (Fig. 320). A similar groove appears 

 on the jaws of later theriodonts. Jaws carrying triconodont teeth but 



Fig. 320. A, triconodont (Priacodon) from the Jurassic; B, lingual view of lower jaw 

 of a docodont; C, multituberculate {Ptilodus) from the Palaeocene. c.a. canine alveo- 

 lus; gr. groove; m. molars; m.j. mandibular foramen; p.m. premolar; ri. ridge; tr. 

 trough. (A and C after Lull, Organic Evolution, copyright 191 7, 1929 by The 

 Macmillan Company and used with their permission. B after Kermack and Mussett.) 



without the groove have long been known from the Jurassic (*Amphi- 

 lestes). They may represent an offshoot from a stock like the doco- 

 donts. 



The multituberculata were the most numerous and long-lasting 

 Mesozoic mammals, surviving from the early Jurassic period to the 

 lower Eocene. They were herbivorous and sometimes of large size 

 (Fig. 320). Between the incisors and the molariform teeth there was 

 a gap (diastema), as in other mammals that chew large amounts of 



