A'lII. — The Reconstruction of a Cretaceous Dinosaur, Clao- 

 SAURUS annectens Marsii. By Charles E. BEEniEi?. 

 (Witli Plates XLI to XLV.) 



Tntrocluctio7i. — The completion of the mounting of the skeleton of 

 a large dinosaur is a matter of considerable moment to any museum, 

 as well as of some general scientific interest. Although the subject 

 lies wholly outside the particular field of research of the writer, it 

 still seems desirable to present, even imperfectly, some description of 

 a specimen which is in many ways unique, and by chance is the first 

 (linosaurian skeleton to be mounted in America. 



In most kinds of construction the concrete result is usually found 

 to differ in many particulars from the ideal or mental picture as 

 ■expressed in language or by an artist. This being a general state- 

 ment of fact, one would naturally expect some discrepancy between 

 the pictured restoration of the skeleton of an extinct animal and the 

 skeleton itself when actually put together and mounted. 



The limitations of paleontologic work require that in order to give 

 A general conception of an animal, this must be represented by a 

 drawing or model in which the missing parts are restored according 

 to the best knowledge and inference on the part of the investigator. 

 The more complete the material studied, the more satisfactory and 

 accurate the restoration is likeh' to become. An illustration of this 

 fact will appear later on. 



Ea'cu when approximately entire skeletons of fossil vertebrates are 

 •discovered, the bones are usuall}^ found displaced, and their nature 

 and position are determined principally by comparative studies on 

 other better known animals supposed to be related or to have anal- 

 ogous features. In the study of a group of vertebrate animals that 

 is wholly extinct and has left no direct descendants, the difiiculties 

 of attempting to make a restoi'ation of any particular type are con- 

 siderably increased. This applies either to a drawing or to the 

 moimting of the skeleton in a manner which shall be rendered true 

 to nature, by placing all the bones in their proper position and 

 giving the skeleton a posture it may have had during life. It has 

 therefore come about that the positive information conveyed by the 

 Jinding of a foot or of any other portion of a skeleton, with the 

 bones in a sequential position in the rock, is of far greater anatomi- 

 cal value than any number of expert opinions. 



