THE AUSTRALIAN MUSEUM MAGAZINE. 



315 



similar conditions, they branched out 

 in many directions in obedience to the 

 law of Adaptive Radiation f o con- 

 vincingly expounded by Dr. H. F. 

 Osborn. Some were swift destiuctive 

 flesh-eaters, preying u|)on their weaker 

 fellows as the lion, the wolf, and other 

 carnivores do to-day ; others were 

 vegetable feeders, comparable with 

 modern hoofed mammals. Some, as 

 the Ichthyosaurus and Plesiosaurus, 

 became adapted to a marine life like 

 our Avhales and porpoises ; still others, 

 the pterodactyls, took to themselves 

 wings and flew through the air like 

 birds. 



But of all the reptiles of the period 

 the dinosaurs were the most remarkable. 

 Apparently they originated in the Tri- 

 assic as lizard-like forms with long 

 limbs and tails, having five toes on each 

 foot armed with sharp claws. These 

 ancestral forms were probably adapted 

 to live on dry land, and their gait was 

 more or less bipedal or kangaroo-like. 

 This central type gave rise to a great 

 variety of forms. Some were carniv- 

 orous, others herbivorous, some were 

 gigantic, almost equalling modern 

 whales in bulk, others were quite small, 

 some walked on all fours, others on their 

 hind legs ; some were dwellers on the 

 dry land, others wallowed in the waters 

 of rivers and lakes like the hippopota- 

 mus. Many were provided with bony 

 armour-plates or armed with formidable 

 horns or spines ; some had long sharp 

 claws, others hoofs. In fact, in their 

 time, the dinosaurs played much the 

 same part as the larger mammals now 

 inhabiting the earth. And the explan- 

 ation is simply that in nature there are 

 certain roles to be filled, and the actors 

 are chosen by natural selection from 

 the material available. As Dr. W. D. 

 Matthew has well said, if birds and 

 mammals were to be exterminated by 

 some cataclysm, it is probable that 

 existing lizards would, in the course of 

 ages, evolve into a fauna not unlike 

 the dinosaurs of old. 



The remains of these land dragons 

 have been found practically all over 

 the world ; even in Australia, which 

 seems to have been a " lonely conti- 



nent " for numy ages, we find slight 

 traces of dinosaurs. Rut it is in 

 America tha tthe greatest finds of these 

 long extinct creatures have been made. 

 From the great delta formations of the 

 Middle Western States and the Alberta 

 district of Canada, successive exploring 

 parties sent out by the leading American 

 museums have brought back a won- 

 derful series of dinosaur bones, and the 

 patient labours of many scientific 

 workers in America and Euro])e have 

 made the structure of some of these 

 long dead creatures almost as well 

 known to us as that of animals now 

 living. We know even what their 

 integument was like, through the 

 fortunate circumstance that the mum- 

 mified body of a dinosaur became em- 

 bedded in fine sediment which took an 

 impression of its skin. 



the amphibious dinosaurs (sauro- 

 poda). 



Dinosaurs are divided into groups 

 according to their structure. The 

 Sauro]ioda or Lizard-footed Dinosaurs 

 were the largest of all, and Dvplodocns, 

 Brontosaunis, and Brachiosaurus, which 

 belonged to this group, were much 

 larger than any animal now living, 

 with the exception of the largest whales. 

 Diplodocus, for example, was over 

 eighty feet long. As the Sauropoda 

 are supposed to have lived partly on 

 land and partly in water they are some- 

 times called the Amphibious Dinosaurs. 

 All the members of this group were 

 quadrupedal in gait. They had a very 

 small head, blunt teeth, long neck and 

 tail, a compact slab-sided body, and 

 massive limbs terminating in five -toed 

 feet. /'They lived during the late Jur- 

 assic and early Cretaceous, becoming 

 extinct in the mid-Cretaceous period. 



Camarasaurus, a smaller relation of 

 Diplodocus and Brontosaurus, is repre- 

 sented in our collection by an original 

 thigh bone five feet three inches in 

 length and weighing 388 pounds in its 

 petrified state, by a beautiful model, 

 one -tenth natural size of the animal as 

 it appeared when alive, and by a fine 

 drawing of the skeleton. The model 

 and drawing, both executed by the late 



