Pseudhipparion

kuda kecil berkuku tiga dari 15 juta tahun lalu

Bacaan lanjut
http://ashfall.unl.edu/ashfallgeology.html
http://www.youdebate.com/cgi-bin/scarecrow/topic.cgi?forum=3&topic=40784
S. D. Webb and R. C. Hulbert. 1986. Systematics and evolution of Pseudhipparion (Mammalia, Equidae) from the late Neogene of the Gulf Coastal Plain and the Great Plains. Contributions to Geology, the University of Wyoming, Special Paper 3:237-272 [J. Alroy/J. Alroy/J. Alroy]

Sumber gambar
http://www-museum.unl.edu/research/vertpaleo/ash-feat.html