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出典:Wikipedia
出典:『Wikipedia』 (2011/06/08 22:49 UTC 版)
Protoceras ('first horns') is an extinct genus of Artiodactyla, of the family Protoceratidae, endemic to North America from the Oligocene through Miocene (Orellan to Harrisonian stage) 33.9—20.6 Ma, existing for approximately 13.3 million years.
Protoceras