Gastroliths.

  • Wieland, G. R. (George Reber), 1865-1953.
Date:
1907
Catalogue details

Licence: In copyright

Credit: Gastroliths. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    thus still more closely locate the actual hab- itat and haunts of the sauropods. At least it already appears that the dinosaurs of the Big Horn and Colorado localities either picked up the fossiliferous nodules on the same ancient shore line, or else from streams which cut this line along some inland range of hills or moun- tains and carried the pebbles forward into the lower river courses. In the latter and more probable case the dinosaurs would have found the transported fossil bearing pebbles inter- mingled with a variety of others just as in the two occurrences now observed. It should be definitely stated that the dino- saurian gastroliths are unmistakable objects. Pebbles which are merely waterwom rarely have other than ground glass surfaces, and where a partial polish approaching a sheen is present, this does not markedly extend into depressions, and is much interrupted by vari- ous irregularities. So also the wind-worn pebbles of steppes, although I have seen near the glacial ice sheet limit of eastern Nebraska large boulders of Sioux quartzite presenting small polished areas due to seolian action; while in the case of the readily determinable desert patina the glassy surfaces are of a some- what different origin. But from all these the dinosaurian gastroliths will never fail of recognition. Except for the original inequali- ties of the pebble outline, though even these may be nearly eliminated, their entire surface may exhibit a higher polish than wind or water ever produces. Indeed the smoothness and sheen are, I may say, from my section making, such as is difficult to equal, and best compared to the finest results obtained by the use of the buffing wheel. It is evident that the dinosaurs were more or less given to selecting the pebbles they swallowed, choosing the brighter colored ones, much as do the ostriches and other birds. And it appears that pebble-swallowing is quite