GEOLOGY OF THE LARAMIE PLAINS 



The Jurassic beds are well exposed in the Como anticlinal, 

 in the Freezeout Mountains, and the Freezeout Hills, and on 

 Little Medicine. In the upper portion chest layers are occa- 

 sionally present. Lower down are found mollusca of the fol- 

 lowing species, viz: Camptonectes extenuatus, C. bellis- 

 triata, Ostrea strigilicula, Pecten Newherryi, ^elemnites 

 densus, Belemnites e^ucronata, Trapezium subaequalis. 



But it is the upper Jurassic that has made this formation 

 pre-eminently interesting, that has attracted people from every 

 direction to Wyoming, to dig out and view the wonderful fossil 

 treasures, the saurians small and large, and dinosaurs over 1 00 

 feet long. The world wonders at the discoveries. I only saw 

 portions of the skeletons, including a femur of a brontosaur, at 

 Laramie University, 69 inches long. I obtained the vertebral 

 joint of a dinosaur one foot in diameter. The leg bones of the 

 brontosaur would indicate a height of at least 1 5 feet. 



Fifty species of saurians have been taken from these 

 beds. Some of the dinosaurs were reptile-footed, some were 

 bird-footed, some were beast-footed. Some were related to 

 the crocodile, others presented the characteristics of birds. 

 Some were carniverous, others herbiverous. Some were cov- 

 ered with bony plates, others had horns. The stegosaur had 

 a series of pointed plates rising as spines three feet high along 

 the dorsal ridge. The adantosaur of Marsh had a thigh-bone 

 over six feet long. 



Twenty-five years ago Prof. O. C. Marsh of Yale Univer- 

 sity quarried from the beds at Como bones of larger animals 

 than had yet been found. They were chiefly saurians and 

 varied from the size of a small animal to that of the atlantosaur, 

 1 30 feet long. After that for ten years Professor Marsh worked 

 more or less at these beds. 



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