L I 



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 hisitory of life, and its time is 

 measured in millions of years rather 

 than centuries as eivilization is measured. 

 The time that civilized man. has ruled 

 the earth is to the time that life has 

 been upon it, as a day is to the average 

 life of a man. 



In tihe remote past many orders of 

 reptiles and other animals flourii^hed dur- 

 ing' their time, then passed away, in many 

 cases leavin,g no desoendantis. Were it 

 not for the fact that many of these 

 ancient animals left their bones entombed 

 in the rock that was laid down at t)ie 

 time when they lived, we would know 

 nothinpr about the animals that inhabited 

 the earth in past geological ag-es. 



Among the most interesting and re- 

 markable of these animals were the dino- 

 saurs whicin 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 Pi'ofessor Owen, the eminent English 

 ))alaeontologist and anatomist. The dino- 

 saurs were an order of reptiles com- 

 prising the largest land animals of which 

 we have any knowledge, and in most 

 classifications of the animal kingdom hold 

 tbe same rank as the Chelonia (tortoises 

 and turtles) and Squamata (lizards, 

 snakes, 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 having 

 been found on each of the six continents, 

 although Nortel America has yielded by 

 far the greatesit number of genera and 

 complete sipecimens. 



The dinosaurs varied greatly in size, 

 structure and habits, but all of them are 

 noted for their small and primitive brain. 

 Wliile some of the amphibioiLs form.s. 

 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 leng*tji. The 

 small carnivora were very slender and 

 without doubt ^^•ere fleet-footed and ac- 

 tive. Tbe armored forms were heavy- 

 boned, clumsy, slow-moving creatures. 

 Some forms must have taken to the 

 water for defeiice, wihile others were 

 provided witih horns, and yet others were 

 completely inea.sed in dermal armor or 

 plates of l)one in the skin. They all 

 ])Ossessed foui* limbs, thougjii in some 

 the front pair were veiy small. None 

 of the dinosaurs had the power of flight 

 so far as known, thougih a contemporary- 

 order of reptiles, the Pferodaciyles, miLst 

 liave been as gi-aceful flyers as our pres- 

 ent-day bats. The amphibious forms 

 (Sauropoda) must have spent much of 

 Iheir time in the water. Some stude" 

 believe that they never left the water, 

 though of course like all reptiles tlie>- 

 were compelled to keep the nose above 

 water to breathe. In thi,s sub-order are 

 l)laced Gigaiiiosaurvs, Brontosaiirus, Di- 

 pJodocus, etc. 



C(>rtain of the carnivorous forms were 

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

 sk(^leton 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 through 

 the dinosaurs, while other? believe that 

 botji birds and dinosaur-; were derived 

 from a common ancestor. The similarity 

 of cei-tain dinosaurs to b:3 is is most no- 



