300 A. 8. Biggs — Brachiosaurus altithorax. 



stratum in which the bones were imbedded "pinched out" 

 and was replaced by a thickening of the massive ledge of sand- 

 stone which overlaid it. The presence of pebbles at the base 

 of this sandstone, as well as the uniform direction in which the 

 ribs were displaced, showed that the anterior portion of the 

 skeleton had been carried away by the action of a water-current 

 before it had become thoroughly imbedded. 



When the surface fragments of the humerus had been care- 

 fully collected and fitted to the portion still in position, that 

 bone stretched out to such an unheard-of length that the writer 

 was for the time convinced that it must be a crushed femur. 

 This conclusion was given additional weight by finding, soon 

 after, a well preserved femur of almost identical length. How- 

 ever, when removed from the matrix in the laboratory and the 

 two compared, all doubt was removed by the characteristic form 

 of the head of the humerus as well as the presence of a well 

 defined deltoid crest, 



The length of the humerus and femur, together with the 

 immense size of the thorax, at once establishes the fact that 

 this is the largest and longest-limbed of all known land animals, 

 as well as the only dinosaur known to science in which the 

 humerus is longer than the femur. Assuming that the lower 

 fore-leg bones were proportionately long, we have to do with 

 a creature whose shoulders were carried far above his hips and 

 whose fore-legs played a more important part than the hind 

 ones. Such proportions at once suggest arboreal food-habits. 

 Instead of rearing upon the hind legs and supporting itself by 

 means of a ponderous tail, as were the evident habits of Bronto- 

 saurus and Diplodocus, this animal may from sheer length of 

 limb have been able to browse at will upon the foliage of tree 

 and shrub. What were the proportions of the neck can only 

 be conjectured ; to be consistent with the proportions of body 

 and limbs it must have been long and flexible. The short 

 spines and the slight processes of the anterior caudals show that 

 the tail was much reduced both in size and in length. This 

 then was the giraffe among dinosaurs, just as Claosaurus was 

 the kangaroo. 



Description of Skeleton. 



The humerus is somewhat crushed antero-posteriorly and 

 twisted so that the head and distal end are brought into the 

 same plane (fig. 1). The surface of the distal end has flaked 

 away in the process of weathering to a firm chalcedony core. 

 In proportions the humerus approaches more nearly to that of 

 Diplodocus than to any other well-known American genus. The 

 head is considerably expanded, forming a rounded prominence 



