THE AUSTRALIAN MUSEUM MAGAZINE 



319 



The giant carnivorous Dinosaur, Tyrannosaurus, approaching Triceratops. a herbivorous 

 relative on which it probably preyed. From a drawing by C. R. Knight. 



[Courtesy of the American Museum of Satnral History. 



EXTINCTION OF DINOSAURS. 



Many suggestions have been made to 

 account for the extinction of these rep- 

 tiles, which seem to have been built 

 to endure for all time, but it is always 

 difficult to discover the causes of ex- 

 tinction of organic types. Looking 

 down the great vista of the past we are 

 apt to think that the dinosaurs evolved, 

 reached their culmination, and then 

 suddenly died out. But in reality the 

 process was one of extreme slowness, 

 spread over millions of years, and, once 

 we realise that important fact, we 

 cease to wonder at their disappearance. 

 The great American naturalist. Cope, 

 suggested that the small cunning mam- 

 mals, which had already made their 

 appearance before the Age of Reptiles 

 drew to its close, would seek out and eat 

 the eggs of their formidable contem- 

 poraries. A more plausible explan- 



ation is that great geographical changes 

 took place, the swamps necessary for 

 some kinds of dinosaurs were drained by 

 elevation of the land, aridity increased 

 and the climate grew more severe. 

 Reptiles as a class are more susceptible 

 than birds or mammals to changes of 

 temperature, for they are cold-blooded 

 and have no covering of feathers or hair 

 to protect them against cold. Then, 

 too, the large size and over special- 

 ization of many dinosaurs handicapped 

 them for life's race. A large animal 

 requires more food than a small one, 

 and any considerable alteration in en- 

 vironment is fatal to a creature which 

 has become specially adapted to hve 

 in a certain way and cannot adjust 

 itself quickly enough to changed con- 

 ditions. Palaeontology is continually 

 enforcing the lesson that large size and 

 extreme specialization almost always 

 presage extinction. 



Professor T. Thomson Flynn, Liii- 

 versity of Tasmania, Hobart, is at 

 present carrying on certain investiga- 

 tions relating to the internal organs 

 of the Blue Tongue or Sleeping Lizards, 

 a large well-known species belonging to 

 the genus Tiliqua. As a large number of 



specimens is required, readers would 

 be rendering a great service by send- 

 ing any they may secure to the Aus- 

 tralian Museum. It does not matter 

 whether they be alive or dead so long 

 as the abdominal organs are intact 

 and uninjured. 



