January 18, 1906] 



NA TURE 



283 



connection the writer's assistants, Messrs. Mattl 

 Granger, made a complete restoration of the muscles of 

 the shoulder girdle and of the neck on the basis of dissec- 

 tions of the alligator and lizard. As a result, two 

 important modifications of previous restorations have been 

 made, first, the scapula is considerably more depressed 

 below the level of the back than in previous restorations, 

 thus allowing" space for the cartilages between the ribs and 

 coracoid, second, the elbows are considerably everted. 

 In all previous restorations the manus is represented as 



aquatic theory suggi sted • > n his original study of 



Cetiosaurus on account of the shape i I the caudal vertebra, 

 and partly supported by Cope on the ground of the extreme 

 lightness of the dorsal vertebra? ; this has been more 

 recently supported by Matthew and Gidley on the ground 

 that the limbs were incapable of progri ssion upon land, and 

 were very much K flexed than in any of the 



restorations of the animal which have been published. 

 The amphibious theory lias been partly developed by Cope 

 and the present writer, namely, that the animals spent a 



-Skull of the Moro 



provided with a nearly complete series of terminal claws 

 like those of the pes, which lacks the terminal claw only on 

 two digits. Comparison of ten specimens of Sauropoda in 

 various museums has convinced the writer that, according 

 to present evidence, in Diplodocus and Brontosaurus there 

 is but one claw in the manus, and that a small one, on 

 the pollex. The arching and elevation of the backbone 

 also come in for considerable modification. Although, as 

 previouslv supposed by the writer on other grounds, the 

 sacrum was the centre of power and of motion in this 

 great animal, as a result of the depression of the scapula 

 the posterior portion of the neck and middle portion of 

 the back were elevated, and the highest vertebra of the 

 back is not necessarily the spine of the sacrum. Another 

 characteristic of all Sauropoda is the elongation of the neck 

 and the extreme abbreviation of the back, which now in 

 several forms is found to be composed of from ten to eleven 

 vertebrae only. Brontosaurus seems to differ from Diplo- 

 docus in the relative abbreviation of length as a whole 

 correlated with the greater massiveness of the skeleton, but 

 especially in the abbreviation of the tail. 



C "™ a,s lobars Sa " als Caudals 



Brontosaurus ... 13 est. ... 10 ... 5-6 ... 49 +est. 

 Diplodocus ... 15 ... 11 ... 4-5 ... 35-40 



In three specimens of Diplodocus evidence has been found 

 of the consolidation of certain vertebra; of the tail (caudals, 

 17-1S and 19-21) at the point where they reach the ground. 

 From this it has been inferred that the tail was used 

 partly as a bracing or supporting organ when the anterior 

 half of the body was elevated. There is no evidence of 

 such consolidation in Brontosaurus, and the tail was re- 

 latively much shorter. Another difference is that in the 

 tail of Diplodocus the vertebral spines are very lofty, and 

 the . transverse processes laterally compressed, indicating 

 that this organ was partly used for propulsion in the 

 water. These characters are much less strongly developed 

 in the massive limbed Brontosaurus. 



In this connection we may mention two partly antagon- 

 istic theories of the habits of this animal. First, the 



considerable part of their life in the water, but were also 

 capable of progression, and even of feeding, upon land ; 

 that during the reproductive and hatching period they 

 spent a considerable time on land guarding their nests. 

 A similar theory was advocated by Hatcher in his memoir 

 on Diplodocus. 



The size of the Brontosaurus has been very generally 

 overestimated. The chief measurements of the present 

 skeleton as mounted are : — 



Length over all from head to tip of tail ... 

 Length of vertebral column ... 

 Length of neck... 



Length of tail 



Length of longest rib... 

 Length of hind-limb, including foot 

 Length of fore-limb, including foot... 

 Depth of body from lower end of pubis 



to top of posterior dorsal spine ... 

 Length of head as restored ... 

 Estimated weight of animal when alive 



Feet Inche 

 66 8 



38 tons 



NO. 189O, VOL. 73] 



As above noted, the long-limbed Diplodocus attained a 

 greater length ; the specimen recently presented to the 

 British Museum is 84 feet long. The little known Baro- 

 saurus, related to Diplodocus, was of still larger size, and 

 the Brachiosaurus of Riggs had a much greater length of 

 limb, but we have no means of ascertaining its length 

 over all. 



It is interesting to compare these measurements with 

 those of a fully grown " sulphur bottom " whale, care- 

 fully measured by Mr. F. A. Lucas, and reproduced at the 

 St. Louis Exposition. This animal, a male, measured 

 74 feet S inches from the notch of the flukes to the tip 

 of the nose. The approximate weight of the bones was 

 17,920 pounds. The entire animal was estimated at not 

 much less than 63 tons. 



Our estimate of the weight of Brontosaurus is based on 

 a model by Mr. Charles R. Knight on a one-sixteenth scale, 

 founded upon the actual measurements of the present 

 skeleton. As carefully estimated by Mr. W. K. Gregory 



