REPTILE RECONSTRUCTION GILMORE. 275 



surfaces in the dinosaurs are usually poorly defined, and afford lit- 

 tle evidence concerning the exact manner of articulation of bones 

 found detached and misplaced. For this reason any information 

 conveyed by the finding of an articulated specimen with bones in 

 sequential position in the rock is more to be relied upon than any 

 number of expert opinions. As a rule specimens so exhibited also 

 hold the attention of the average museum .visitor far longer and 

 arouse a keener interest in the genuineness of the specimens than does 

 a skeleton that has been freed from the rock and mounted in an 

 upright lifelike posture. 



To the layman the type of Thescalosdums neglectus is of interest 

 as showing the skeleton in the same position as when covered up 

 millions of years ago ; and to. the vertebrate paleontologists it will 

 long remain a standard for interpreting and coordinating the scat- 

 tered and isolated parts of others of its kind. 



In life this animal was about 12 feet in length and evidently strong 

 and agile in movement. The tail was long, equaling one-half the 

 entire length of the skeleton, which served as a balancing organ 

 when the upright bipedal posture was assumed. In rapid locomo- 

 tion Thescelosaurus doubtless progressed entirely upon its hind legs, 

 as do many of our living lizards, the short fore limbs being used 

 for sustaining the fore part of the body when feeding from the 

 ground. 



While the head is unknown the resemblance of the skeleton to other 

 well-known dinosaurs indicates that it was in all probability a plant 

 eater. The foot structure would imply that it was more of an upland 

 animal rather than an inhabitant of swampy areas. 



In modeling the restoration shown in plate 3, the missing head 

 and neck were restored from a closely related form in which these 

 parts are known. In this model an attempt has been made to ex- 

 press the light, agile nature of Thescelosaurus, as is so clearly indi- 

 cated by the skeleton and especially by the cursorial structure of the 

 hind limbs. 



The animals briefly reviewed in the preceding pages all lived 

 during the Upper Cretaceous geological period, estimated by the best 

 authorities as being between 6,000,000 and 7,000,000 years ago. 

 Dinosaurs, however, existed long before that time in what is known 

 as the Upper Jurassic, and attention is now called to typical repre- 

 sentatives of the reptilian inhabitants of that period which is esti- 

 mated to be 10,000,000 or more years old. 



One of the most interesting was the Stegosaw i us, or plated lizard. 

 They were by reason of their large size and ornate bony skin struc- 

 tures the more striking and characteristic of the large reptilia that 

 inhabited the Northern Hemisphere in those long past ages. It 

 should be stated, however, that this family is not confined exclusively 



