i 



LIBRARY 



THE CANADIAN FIELD-NATURALIST^ 



# 



VOL. XXXV. 



GARDENVALE, QUE., APRIL, 1921 



No. 4. 



A POPULAR DESCRIPTION OF DINOSAURS. 

 By C. M. Sternberg. 



Introduction. Palaeontology deaLs 

 with the history of life, and its time is 

 measured in millions of years rather 

 than centuries as civilization is measured. 

 The time that ci"vilized man has ruled 

 tihe earth is to t,he time that life ha.s 

 been upon it, as a day is to f^e averag-e 

 life of a man. 



In the remote past many orders of 

 reptiles and other animals flourfeJied dur- 

 ing their time, then passed away, in many 

 cases leavinor no descendants. Were it 

 not for the fact that many of these 

 ancient animals left their hones entombed 

 in the rock that was laid down at t/ie 

 time when they lived, we would know 

 nothinfj about tIhe animals that inhabited 

 the earth in past geological ages. 



Among the most interesting and re- 

 markable of these animals were the dino- 

 saurs whie.h were so abundant during 

 the Mesozoic Era. 



General Discussion. The name Dino- 

 saur is taken from the Greek and means 

 Terrible Lizard. It was first proposed 

 by ProfesJsor Owen, the eminent English 

 palaeontologist and anatomist. The dino- 

 saurs were an order of reptiles coni- 

 l)rising the largest land animals of which 

 we have any knowledge, and in most 

 classifications of the animal kingdom hold 

 the same rank as the Chflonia (tortoises 

 and turtles) and Squamaia (lizards, 

 ^luikes, etc.). They were the dominant 

 type of land animals during the Mesozoic 

 period or Age* of Reptiles, which lasted 

 some millions of years and closed at least 

 three million years ago. They were 

 widely distributed, their bones Ihaving 

 been found on each of the six continents, 

 although Nort,h America has yielded by 

 far the greatest numbei- of genera and 

 complete specimens. 



The dinosaurs varied greatly in size, 

 structure and habiis, but all of them are 

 noted for their small and primitive brain. 

 Wliile some of the amplhibious forms, 

 of Jurassic age, attained a length of 

 one hundred feet, others were very small, 

 Compsoganthus, a carnivore of Jurassic 

 age, being only two feet in leJig^tjh. Th(^ 

 small carnivora were very slender and 

 without doubt were fleet-footed and ac- 

 tive. The armored forms were heavy- 

 boned, clumsy, slow-moving creatures. 

 Some foruLs must have taken to the 

 water for defence, wthile others were 

 provided with horns, and yet others were 

 completely incased in dermal armor or 

 plates of bone in tihe skin. They all 

 possessed foui- limbs, though in some 

 the front pair were veiy small. None 

 of the dinosauiN had the power of flight 

 so far as known, though, a contemporars- 

 order of reptiles, the Pterodactyles, must 

 have been as graceful flyers as our pres- 

 ent-day baits. The amphibious forms 

 (Saiiropoda) must have spent much of 

 their time in the water. Soime studen 

 believe that they never left the water, 

 though of course like all reptiles they 

 ^vere eompelled to keep the nose above 

 water to breathe. In this sub-order are 

 placed Gigantosmirus, Brontosatirus. Di- 

 pJodocus, etc. 



Certain of the carnivorous forms' were 

 so bird-like that, w^iere only part of the 

 skeleton was known, they have been called 

 birds. Because of the great similarity- 

 between these forms and certain birds, 

 some students believe tlhat in the course 

 of evolution, the birds evolved throug^h 

 the dinosaurs, while other; believe that 

 both birds and dinosaurs were derived 

 from a common ancestor. The similarity 

 of certain dinosaurs to b:j is is most no- 



