The Hadrosaur Edmontosaurus from the Upper 
Cretaceous of Alberta. 
INTRODUCTION. 
The Hadrosauridse^ are a group of herbivorous dinosaurs of which 
most of the genera are from the continent of North America. The literature 
relative to this family is both voluminous and involved. The earlier 
descriptions were based often on inadequate material which gave little 
information as to the relations of the forms represented and their variety 
which has proved to be much greater than was at first supposed. The 
rapidity of the evolutionary changes that took place in these reptiles 
during Cretaceous times, especially toward the close of the period, resulting 
in a wonderful diversity of form, could not, in the circumstances, be fully 
appreciated. At the early stage of geological and palaeontological investi- 
gation the horizons supplying dinosaurian remains had been only broadly 
determined. Geological exploration was at that time carried on, in the 
west particularly, under trying and arduous conditions; transportation 
was difficult; and rough-and-ready methods of collecting were used by 
parties most inadequately equipped for field work according to present 
day standards. It is not surprising, therefore, in spite of the brilliancy 
of the pioneer few who undertook palaeontological investigation, and the 
ardour which they brought to bear on their work and by which they were 
upheld, that errors were not avoided. It does not detract from the excel- 
lence of their results to now find that diversity of form was not always 
recognized, that, for instance, generic terms were employed to include 
types not only widely separated by time intervals but also by very decided 
differences in structure. 
Recent discoveries during the last six years in the Belly River and 
Edmonton formations on Red Deer river, Alberta, of nearly complete 
skeletons of several distinct types of hadrosaurs have provided excellent 
material for study and description, thrown much light on the osteology 
of the group, and opened the way for a classification of its members. 
In the following pages a description of the large hadrosaur Edmonto- 
saurus regalis, Lambe^ from the Edmonton formation of Red Deer river, 
Alberta, is followed by a proposed division of the Hadrosauridse into 
three subfamilies the classification being based principally on type and 
other material resulting from the exploratory work of vertebrate palae- 
ontological field parties of the Geological Survey, Canada, in Alberta, 
largely supplemented by the discoveries of the American Museum of 
Natural History, New York, in the same region and to the south of the 
International Boundary. 
Of the two skeletons on which the genus Edmontosaurus was estab- 
lished in 1917, one is unique in that the majority of the bones of the head 
and of the remainder of the skeleton were found together naturally dis- 
iThe name Hadrosauridee proposed by Cope in 1869 (1871) has precedence over Trachodontidse used by 
Lydekker in 1888 and later by Marsh in 1890. 
2A new genus and species of crestless hadrosaur from the Edmonton formation of Alberta; Ottawa Naturalist, 
vol. XXI, No. 7, Oct. 1917, pp. 6&-73, pis. II and III. 
