Tetraclaenodon was a genus of small and early ungulate mammals that was part of the Phenacodontidae family. It is the oldest and most primitive phenacodontid. Its fossils known from the Nacimiento Formation, New Mexico. In 2012, Tetraclaenodon was defined as the basalmost member of the clade containing "Phenacodontidae" and Altungulata.
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