THE HABITAT OF THE SAUROPOD DINOSAURS 
CHARLES C. MOOK 
American Museum of Natural History 
INTRODUCTORY 
In the study of the sauropod dinosaurs which has been carried 
on by the writer for a number of years under the direction of Pro- 
fessor H. F. Osborn in connection with the preparation of the 
latter’s monograph on these reptiles, some problems have presented 
themselves upon which a study of the habitat, or immediate 
environment, has a bearing. 
The course, or trend, of evolution in a group of organisms is 
limited, or controlled, by two things: (1) the heritage or assemblage 
of characters inherited from the ancestors; and (2) the environment. 
The environment offers the organism opportunities for developing 
along a limited number of lines. What these lines will be depends 
upon the general character of the environment. For instance, 
upon inland plains advanced aquatic adaptations, such as are 
characteristic of marine organisms, will be barred out, and under 
strictly-marine conditions the development of cursorial locomotor 
apparatus is impossible. This is true no matter what may be the 
heritage of the organism under discussion. Within certain limits, 
however, the environment offers the possibilities or opportunities 
for evolution along a number of lines. The heritage furnishes the 
material or instruments by which, or by a modification of which, the 
organism may evolve along one or more of these lines. 
In working out adaptations and habits in a group of animals 
such as the Sauropoda, morphology, together with comparison with 
living forms, will be the most important guide. Morphological 
- structures have meanings, and if these meanings can be interpreted 
the habits of the animals possessing the given structures can be 
determined to a certain extent. A study of the environment of 
459 
