THE POSE AND LOCOMOTION OF DIPLODOCUS 13 



One of these species, Anchisaums colurus was described by Marsh 

 from the Triassic of the Connecticut Valley, and he published a 

 restoration of the skeleton in his work The Dinosaurs of North 

 America, PL IV. Dr. R. S. Lull 7 has identified this dinosaur as the 

 maker of the tracks known as Anchisauripus dananus (Hitch.) This 

 identification is extremely interesting, in case it can be substantiated. 

 The bones of the hind foot of Anchisaums colurus fit accurately in the 

 tracks named. These tracks are placed close to or on the line along 

 which the animal was moving, the "line of direction" (Beckles), and 

 there are, in the several specimens known, no indication of impres- 

 sions of either the fore feet or the tail. 



A study of the various printed restorations of this species reveals 

 an animal of elongated body, with limbs not greatly unlike those of a 

 crocodile, the hinder legs being a little longer in proportion to the 

 length of the body than in the crocodile, while the fore legs are about 

 three-fourths the length of the hinder ones. In the crocodile the fore 

 limb is little more than two-thirds as long as the hinder. 8 As com- 

 pared with the hind foot of the crocodile that of Anchisaums is a little 

 longer. Now, with this view of the creature, what is there in it to lead 

 one to suppose that it erected itself on its hinder limbs, unless it were 

 on rare occasions; and on such occasions would it not have borne 

 itself as did the running lizard figured by Saville-Kent ? What one 

 is asked to believe is that it bore itself so loftily that it is never found 

 to have put its hands on the ground or to have dragged its tail in the 

 mud. Furthermore, this reptile walked with all the skill and the 

 circumspection of the heron and the barn-yard fowl; for each foot was 

 brought forward and placed very near or on the line of direction and 

 thus immediately under the center of gravity. This is very different 

 from the way in which Saville-Kent's lizard ran; for when a foot was 

 advanced it was placed far from the line of direction and at the same 

 time the tail was jerked violently toward the same side, in order to 

 bring the center of gravity over the advanced foot. The dinosaur in 

 question seems to have had no other use for its tail than to serve as a 

 counterpoise to the weight of the head and trunk. 



Omitting the feet, the legs of most birds consist of three long seg- 

 ments, viz: the femur, the tibia, and the tarsometatarsus. The 



7 Mem. Bost. Soc., Nat. Hist., v. p. 487. 



8 Dollo, Bull. Mus. roy. d'Hist. nat. Belgique, ii, 1883, p. 107. 



