April, 1921. 



The Canadian Feeld-Natubalist. 



63 



similar habitat iiidicaties that the climate 

 was semi-tropical. 



This must have been a mueji favoured 

 Ihaunt of dinosaurs and other reptiles, 

 for there are thousands of individuals 

 represented and of course we see only a 

 very small percentage of the bones that 

 were entombed in the rocks. 



As the animals died on the banks of 

 a river or lake oi* on a delta, the flesh 

 was torn off by some hungry carnivore 

 and t^e bones scattered. In times of 

 flood these bones were picked up and 

 carried to some lake or was)hed upon a 

 mud-flat or isiand^bar. There are a great 

 many extensive "bone beds" or layers 

 in A^Hhich thousands of bones have been 

 deposited, as driftwood would be thrown 

 up on a beach by the waves, or carried 

 on to a mud-flat by back water. These 

 bone beds are usually at the junction of 

 the clay and sand rattier than wholly 

 within either type of deposit. The bones 

 in these deposits are usually disarticula- 

 ted and sihow signs of having been tossed 

 about by the waves. 



Besides these bone beds many skulls 

 and skeletons were deposited more or less 

 complete. Some of these seem to have 

 been washed upon a beach or mud-flat 

 and after the lower ^alf was covered 

 with sediment the exposed portion was 

 torn away by some carnivore leaving 

 only half of the skeleton to be preserved. 

 In otlier cases the animals were mired 

 or the carcases were washed into quick- 

 sand or on to mud-flats where the car- 

 nivora could not reach them. One skel- 

 eton collected shows t]ie remains of rushes 

 which grew among the undisturbed bones 

 and even the skin impression is preserved. 

 It is very common to find skeletons 

 mingled with the remains of vegetation 

 such aisi ruslhes, moss, leaves and branches 

 of trees. The animals which spent most 

 of their time in t^e water are better 

 known than those which habitually lived 

 on land, because after death their bodies 

 often floated into some lake or bayou 

 beyond the reacih of the camivora and 

 were buried intact. 



Kinds of Canadian Dinosaurs. Of 

 the dinosaurs that have left t^eir bones 

 entombed in the Belly River_ and Edmon- 



ton formations along Red Deer river, 

 Alberta, the best known are divided into 

 four families. The most common is that 

 of the duckbilled dinosaurs or Hadro- 

 sauridae. Of this family nine genera 

 have been coDected from Alberta, eight 

 of whiclh have not been found in ot^er 

 deposits. Next in number comes the fam- 

 ily of horned dinosaurs or Ceratopsia 

 of which two genera have been described 

 from the Edmonton and five from the 

 Belly River formations. None of these 

 are known from any other age. The 

 armored dinosaurs or Ankylomuridae are 

 not; as well known as the above-mentioned 

 families. Tji;ie carnivorous dinosaurs be- 

 long to a different sub-order. Tlhey do 

 not possess a predentary (a bone situated 

 in front of the dentary or lower jaw) as 

 do the above-mentioned families. None 

 of the very large or very (small dino- 

 saurs have been found in these deposits. 

 They have been found only in older 

 deposits than those represented on the 

 Red Deer river. 



The duck-billed dinosaurs were heavy- 

 boned creatures w^idh ranged up to forty 

 feet in length. The legs were of unequal 

 size, the hind pair being the larger. The 

 fore-feet had four toes and the hind 

 ones three. The terminal phalanges; of 

 tihe toes of i]ne hind feet and part of 

 those of the front feet bore hoofs. All 

 four feet were webbed. The tail, which 

 comprised about half the length of the 

 animal, was high and narrow, making 

 a powerful swimming organ. The integ- 

 ument was made up of small scales, (non- 

 imbricating and polygonal) wlhich were 

 little thicker than the scales of a snake. 

 At certain intervals there were areas of 

 larger scales or raised bosses whiclh varied 

 in shape and arrangement in different 

 species. It is probable tliat wit/i this var- 

 ied &kin pattern there was a varied color 

 pattern whic^ may have been quite orna- 

 mental. The thin skin and absence of any 

 means of defence, coupled with the web- 

 bed feet and swimming tail, seem to 

 prove beyond a doubt that tjhese dino- 

 saurs spent most of their time in the 

 water or at least took to the water for 

 protection from their enemies. The pre- 

 maxillae and predentaries were expanded 

 and incased in a horny sheath similar 



