lOO EVOLUTION IN THE PAST 



equipped for frontal attacks ; but as his capacious body was 

 not protected with armour, he must have had to rely on his 

 tail to deal with sudden flank assaults. His horns were 

 doubtless of use for other purposes than fighting. If he had, 

 hke elephants, a partiality for roots, he could use them for 

 digging up shrubs and trees. It is not likely that these 

 appendages underwent any improvement as the result of 

 what is called sexual selection. It would certainly be rash 

 to suppose that these cold-blooded, dull-witted creatures 

 exhibited much ardour or discrimination in their love 

 affairs. 



Other dinosaurs also brought a lustre to the waning line. 

 These were remarkable for possessing duck-like biUs, fitted 

 out with an immense number of teeth — ^in some cases two 

 thousand {Hadrosaurus). The dentition seems to have been 

 designed purely for feeding purposes ; at least it was ill- 

 adapted for hostilities. The animals had httle or no armour ; 

 and unless they could trip up a foe, and roU over him, they 

 must have fared iU in a quarrel. Possibly their lines for the 

 most part were in out-of-the-way places, where they could 

 feed on the herbage of lakes and streams in peace and comfort. 

 Some portly creatures attained a length from snout to tail-end 

 of nearly forty feet. 

 CROCODILES Whilst dinosaurs were all on side-paths leading to extinc- 

 tion, less lugubrious was the outlook of the crocodiles. 

 Indications had been made in the last Period that these 

 reptiles were to receive some structural benefits. The im- 

 provements were directed to increasing the flexibility of the 

 backbone ; and to so altering the breathing arrangements as 

 to enable the animal to drown its prey without drowning 

 itself. In early Cretaceous times many old-fashioned forms 

 were still in existence {Pholidosaurus, Goniopholis) ; but 

 later in the Period the improvements apparently were 

 possessed by a vast majority of the crocodiles (Thoracosaurus, 

 Holops). 



The vertebrae of the backbone worked more freely, as 

 they were of concave-convex pattern, fitting each other hke 

 ball and socket. The new breathing arrangement was still 

 more remarkable. Under the old system the nasal passages- 



