LIFE IN THE MESOZOIC EPOCH 



fig. 1330) were short-tailed. But one of the later types (Ptera- 

 nodon] was a toothless reptile with a spread of wing not far 

 short of 20 feet. 



Crocodiles (Crocodilid) and Turtles (Chelonid) were numer- 

 ous during the Mesozoic epoch, and in the later part of it both 

 Lizards (Lacertilid) and Snakes (Ophidid) are known to have 

 existed. 



MESOZOIC BIRDS (AVES). The few mesozoic birds which have 

 so far been discovered have certain characters, e.g. the possession 

 of teeth, which suggest reptilian descent. In the oldest known 

 form (Arch&opteryx)) which has 

 elsewhere been described (see vol. 

 iii, p. 296), the tail was long, and 

 bore pairs of quill - feathers at 

 regular intervals. 



MESOZOIC MAMMALS (MAM- 

 MALIA). That a certain number 

 of small mammals lived during the 

 Mesozoic epoch is known from the 

 discovery of fossil lower jaws in 

 several localities. Some of these 

 suggest affinity with Egg -laying 

 Mammals (Monotrematd), while 

 others probably belonged to small 

 Pouched Mammals (Marsupialid). 

 It has been suggested that Mam- 

 mals evolved from some of the Varied-Toothed Reptiles (Anomo- 

 dontid] on a land-area in the southern hemisphere, which there 

 is some reason to believe once existed (see p. 411). Smith 

 Woodward (in Vertebrate Paleontology] states that in Jurassic 

 (i.e. mid-mesozoic) times " ... it is extremely probable that 

 on some continent in that part of the globe the Anomodontia 

 were gradually being transformed into Mammalia. At least, in 

 the Jurassic formations both of Europe and North America there 

 are occasional remains of small mammals as large as rats; and 

 the most plausible explanation of these is, that they were acci- 

 dental escapes from some other region with a more advanced 

 fauna, just as are the rats and mice of the present day in the 

 comparatively antique realm of Australia." 



Fig. 1330. Pterodactyle (Pterodactylus), reduced. 

 A, Eye; L, lachrymal bone; sc, scapula; co, coracoid; 

 k, humerus; c, carpus; me, metacarpus; i-v (in fore- 

 limb), thumb and ringers; st, sternum; b, abdominal 

 ribs; p> pubis; //, ilium; I v (in hind-limb), toes. 



