314 



THE AUSTRALIAN MUSEUM MAGAZINE. 



A Dinosaur Exhibit, 



By The Editor. 



[This article describes some exceedingly interesting specimens which, through the 

 good offices of Dr. W. K. Gregory, were obtained by exchange with the American 

 Museum of Natural History, New York.] 



THE rise and development of the 

 successive faunas which have 

 peopled the globe can be traced 

 by a study of their fossil remains found 

 embedded in the sedimentary rocks of 

 the earth's crust. These rocks were 

 at one time unconsolidated clay, sand, 

 or mud, and in ages past, as to-day, 

 the bodies of animals sometimes became 

 buried in these deposits, and, as the 

 loose sand and clay became hardened 

 into sandstone and shale, the hard 

 parts of these animals were converted 

 into stone. Now in a quarry or rock 

 cutting our curiosity is sometimes 

 excited by the discovery of the petrified 

 remains of some strange creature that 

 lived and died, perhaps millions of 

 years ago. 



Thus the sedimentary rocks by their 

 contained fossils furnish a record of 

 the past history of life, the lowest rocks 

 containing the most ancient fossils, 

 and palaeontology, or the study of fos- 

 sils, is the science which deciphers this 

 wonderful record. Geological time is 

 measured not in centuries but in mil- 

 lions of years, and the life of man and 

 the whole duration of the human period, 

 is such a short span that it is difficult 

 for us to realise the vast period of time 

 during which life has been evolving 

 on our planet. Since its beginnings 

 the earth has suffered many changes 

 and majestic revolutions, and its living 

 inhabitants as well have had a strange 

 and eventful history. Race after race 

 of animals and plants came into exis- 

 tence, had their day, then wholly or 

 partly disa]>])eared, to be replaced by 

 others in accordance with the law that 

 the fittest survive. 



The latest chapter in this enthralling 

 history we in our pride call the Age of 

 Man, a comparatively short period 



which stretches over no more, perhaps, 

 than a few hundred thousand years. 

 The preceding Cainozoic (recent life) 

 or Tertiary period, which endured for 

 millions of years, is commonly known 

 as the Age of Mammals, for, during that 

 time, there was a wonderful evolution 

 of mammalian life, which reached its 

 climax about the middle of Tertiary 

 time and is now on the wane. The 

 next oldest period is the Mesozoic 

 (middle life) or Secondary, distinguished 

 by a marvellous profusion and variety 

 of reptilian forms, so that it has been 

 called the Age of Reptiles. Eelow the 

 Mesozoic lie the Palaeozoic (ancient 

 life) sediments, in which the most 

 abundant fossils are invertebrates, such 

 as corals, molluscs, and crustaceans, 

 though primitive fishes, amphibians, 

 and reptiles are also represented. This 

 is known as the Age of Invertebrates. 



The Mesozoic period, which chiefly 

 concerns us here, is divided into three 

 sections, which, in order of decreasing 

 age, are called the Triassic, Jurassic, 

 and Cretaceous. All through this vast 

 period of time, which lasted for at least 

 twelve million and j^erhaps several 

 hundred million years, reptiles were 

 the lords of creation. Birds and mam- 

 mals did exist, it is true, but they 

 were apparently poor in numbers and 

 organization, and presented but slight 

 resemblance to the birds and mammals 

 of th3 present day. The mammals, 

 now the dominant race, were then small 

 furtive crtatures, mainly arboreal in 

 habit ; their nearest living relatives 

 are probably the monotremes and 

 marsupials, the characteristic mammals 

 of our own Australia. 



The reptiles of the Mesozoic period 

 flourished amazingly in the absence of 

 serious competition by other forms, and, 

 as will always hajipen in nature under 



