Skulls of different members of the Ceratopsidae, a group of ornithischian dinosaurs. Original caption: “Skulls of Horned Dinosaurs. The lower row, <i>Chasmosaurus</i>, <i>Styracosaurus</i>, <i>Monoclonius</i>, are from the Middle Cretacic (Belly River formation) of Alberta; <i>Anchiceratops</i> is from the Upper Cretacic (Edmonton formation) of Alberta; <i>Triceratops</i> and <i>Torosaurus</i> from the uppermost Cretacic (Lance formation) of Wyoming.”
William Diller Matthew (1871-1930)
1915
<p><i>Dinosaurs - With Special Reference to the American Museum Collections</i>. American Museum of Natural History, New York. 
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Online Source: <a rel="nofollow" class="external text" href="http://www.gutenberg.org/etext/19302">Project Gutenberg</a>