820 



SCIENCE. 



[N. S. Vol. XXIII. No. 595. 



occur in considerable number in the Niobrara 

 shales of South Dakota. In some instances 

 the pebbles were even found en masse, in one 

 large specimen as many as a half bushel being 

 present, ranging from the size of a walnut to 

 four inches across. 



From the regularity of appearance and asso- 

 ciation, Mr. Brown, as it seems to one familiar 

 with the Dakotan Niobrara shales, is very 

 correctly led to the conclusion that these peb- 

 bles served as ' stomach stones.' Such attri- 

 tion stones, I was some years since informed, 

 are habitually swallowed by the Florida alli- 

 gators, and doubtless the habit of swallowing 

 stomach stones, or gastroliths, as I shall con- 

 veniently call them, is and has been wide- 

 spread amongst the reptilia, partly as in the 

 birds. 



Furthermore, Williston in his most recent 

 contribution on North American Plesiosaurs' 

 adds the following remarks to his earlier state- 

 ment : " It was with a specimen of an elas- 

 mosaur (E. Snowii) that Mudge first noticed 

 the occurrence of the peculiar siliceous peb- 

 bles which he described; and it was also with 

 another, a large species yet unnamed from the 

 Benton Cretaceous, that the like specimens 

 were found described by me in 1892. That 

 this habit was not confined to this type of 

 plesiosaur, however, is certain, since I have 

 also observed it in different species of Poly- 

 cotylus and TritMcromerum, both relatively 

 short-necked and long-headed plesiosaurs. 

 Much doubt and even ridicule have been 

 thrown upon this supposed habit, and the use 

 of pebbles by these reptiles. But the cumu- 

 lative testimony of writers, both on this and 

 the other side of the Atlantic, is quite con- 

 clusive. It has been assumed that the plesio- 

 saurs could not have utilized the pebbles as a 

 means of digestion in a muscular stomach. 

 Dr. Eastman, who has vigorously opposed the 

 idea of the possession of such a bird-like 

 structure on the part of the plesiosaurs, seems 

 to have been quite unaware that the modern 

 crocodiles have a real bird-like and muscular 

 gizzard, and are so described by Dr. Gadow. 

 The crocodiles have a similar habit, or at 



» Am.. Jour. Soi., Vol. XXI., March, 1906, p. 226. 



least such a habit has been imputed to them, 

 and it is not at all unreasonable that, strange 

 as it may seem, the plesiosaurs had a real, 

 muscular bird-like gizzard, which utilized the 

 pebbles in whatever way the crocodiles may 

 utilize them." 



Certainly in connection with the foregoing 

 facts it is of more than passing interest that 

 at least some of the sauropodous Dinosauria 

 were stone-swallowers. For one can not help 

 eagerly scanning the record for every indica- 

 tion of the true habits and structure of these 

 extraordinary animals. The evidence for the 

 use of gastroliths by the sauropods rests on at 

 least one authentic instance — namely, that of 

 a large sauropod observed at the northern end 

 of the Big Horn Mountains by Mr. Charles 

 Speer, of Billings, Montana. Mr. Speer found 

 in immediate association with a considerable 

 portion of the skeleton about two dozen quartz 

 gastroliths, which, with various skeletal parts, 

 he took back to Billings, where I saw all this 

 material, September 19, 1902. These speci- 

 mens were displayed in the window of the 

 principal bank of Billings, of which Mr. Speer 

 is cashier, and he has very courteously sent to - 

 the writer at the Yale Museum nine of these 

 pebbles weighing a little over a kilogram in 

 all, and varying from smaller forms to several 

 inches in diameter. These flints vary from 

 gray to brightly colored red and more or less 

 mottled jasper, and include one very highly 

 polished siliceous nodule quite filled with 

 bryozoa and corals, and probably sponge spic- 

 ules. This gastrolith shows the effects of sec- 

 ondary or gastral wear, its more depressed 

 portions clearly displaying the original rough- 

 er true pebble surface. The finely, and even 

 highly, polished and fresh surfaces of all the 

 pebbles would, however, immediately arrest 

 one's attention. In fact the entire surfaces 

 are so surprisingly smooth and clear as to at 

 first suggest a very recent origin, rather than 

 ancient use. It is surmised, however, that 

 immediately following the fossilization of the 

 dinosaurian host, these gastroliths were in- 

 cased in protecting calcite and clay, and that 

 they were never subsequently disturbed till 

 finally eroded out just previous to collection. 



