Mole Skull and Jaw
Mole skull and jaw


The Voracious Flesh-Eater of Hagerman Fossil Beds

Although the title of this article may sound like a low quality, B grade movie, it is rather a translation from the Latin scientific name of one of Hagerman Fossil Beds' rarer animals, Ferinestrix vorax. This animal was first described in 1970 based on specimens found at Hagerman by the University of Michigan and is known from only two bones, a jaw and a femur (upper leg bone). Given the small number of specimens with which to work, it is difficult say much about this animal, but what is preserved is quite interesting.

Ferinestrix (since there is no common name, the first part of its scientific name, the genus, will be used) is a member of the family Mustelidae, which includes weasels, skunks, badgers and wolverines. The slicing tooth (technically called a carnassial) in the jaw is large and massive suggesting it could crush bones. Its overall size was probably only slightly larger than the modern wolverine but the leg bone is more robust suggesting an even stockier and more powerfully built body. Although this animal seems to be closely related to the Old World Honey Badger or ratel, its habits may have been similar to that of a wolverine and its role in the local ecology of 3.5 million years ago may have been that of a scavenger and carrion feeder.

Recently our knowledge of Ferinestrix took a leap forward with the discovery of additional specimens, not at Hagerman, but in South Dakota. Philip Bjork who studied the carnivores of Hagerman and originally described Ferinestrix has found new specimens from a cave/fissure system in the Black Hills. This new find includes bones of the forearm which like the hind leg indicates a strong powerful animal. But the story of Ferinestrix is not limited to North America. Recently it appears the animal has been found in Mongolia. These Mongolian discoveries have not yet been fully studied so we don't know yet if they represent the same or a different species of Ferinestrix. Other interesting questions that need to be answered are whether this new specimen comes from rocks older, the same age, or younger than Hagerman. Since Ferinestrix appears to be related to the Honey Badger which today is found in the Middle East and Africa, it is most likely that the animal originated in the Old World and later entered North America along with other animals such as the bear. Both of these discoveries from outside the Monument will help put the Hagerman fauna into a broader context. Once the Mongolian and South Dakota specimens are studied and comparisons made with the Hagerman specimens, we may have a better idea of the evolution and ecology of this rare animal and the timing of its appearance in North America.

Hagerman may have set the stage with the first discovery of Ferinestrix but it is only by these additional studies of specimens from other locations that we are learning more about this rare animal. Perhaps a more complete skeleton will one day be found on the Monument.

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This article originally appeared in The Fossil Record, July 1996

Last updated: November 22, 2016

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