Stratigraphic Changes in the Pliocene Carnivoran Assemblage from Hagerman Fossil Beds National Monument, Idaho

At least 17 carnivoran taxa occur in the Pliocene Glenns Ferry Formation at Hagerman Fossil Beds National Monument (HAFO), Idaho. This assemblage was examined for stratigraphic changes in species distribution, specimen abundance, and species diversity. Three relatively common mustelids, Trigonictis cookii, Trigonictis macrodon, and Mustela rexroadensis, occur at most stratigraphic levels, but are absent during an interval coinciding with the coolest time segment at HAFO. It is within this gap that two less-common mustelids, Ferinestrix vorax and Buisnictis breviramus, first appear at HAFO; they persist up-section with the more common mustelids listed above. Specimens of Borophagus hilli are restricted to the warm intervals at HAFO, irrespective of the relative abundance of surface water. The other canid at HAFO, Canis lepophagus, is more abundant during the dry intervals at HAFO, regardless of the estimated paleotemperature. Most remarkable is the recovery of many taxa impacted by abrupt climate change, although a notable change is the much higher relative abundance of carnivoran species following a return to warm temperatures.