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This media is in the public domain (free of copyright restrictions). You can copy, modify, and distribute this work without contacting the Smithsonian. For more information, visit the Smithsonian's ...

IN his article on Phenacodus primævus in NATURE of May 16 (p. 57), Mr. Lydekker expresses his disbelief in my opinion that that animal is nearly related to the immediate ancestor of the line of the ...

ALL readers of the American Naturalist must be familiar with a striking woodcut of the entire skeleton of a peculiar fossil Ungulate, which occurs throughout a long series of numbers among the ...

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The present is the key to the past. Every geologist worth their sodium chloride knows this. The famous phrase, a distillation of the principle of uniformitarianism, can be seen emblazoned on mugs, ...

We here describe the endocranial cast of the Eocene archaic ungulate Hyopsodus lepidus AMNH 143783 (Bridgerian, North America) reconstructed from X-ray computed microtomography data. This represents ...

The epic battle waged over dinosaur fossils by rival paleontologists in the American West. In the summer of 1868, paleontologist Othniel Charles Marsh boarded a Union Pacific train for a sight-seeing ...

The shrub-flecked Badlands along Montana’s southern border reek with oil fumes. Scattered among herds of cattle, the oil derricks loom like iron-headed dinosaurs from another age. That’s exactly why ...