Mustelid diversity is well reflected in the Neogene fossil record, in spite of the fact that mustelids are among the rarest of fossil carnivores.
1998, Jon A. Baskin, “9: Mustelidae”, in Christine M. Janis, Kathleen M. Scott, Louis L. Jacobs, Gregg F. Gunnell, Mark D. Uhen, editors, Evolution of Tertiary Mammals of North America: Volume 1, Cambridge University Press, page 169