Mystipterus: Beast of the Week

This week we'll be checking out a newly described prehistoric mammal that I was privileged enough to help introduced to the world.  Let's look at Mystipterus austinae!

Watercolor reconstruction of Mystipterus living in what is now north Dakota, 32 million years ago.  It would have shared its home with land snails, a legless burrowing lizard, and the early canid, Hesperocyon.

Mystipterus was a prehistoric mole that lived in what is now North Dakota during the middle Oligocene period, about 32 million years ago.  Known from mostly just a lower jaw, its body length is estimated at only a few inches long (about 7 centimeters) from nose to tail.  Like its living relatives, it was likely a meat-eater, sniffing out and devouring most invertebrates and possibly other kinds of smaller animals it came across.  The genus name translates to "Impossible to Identify" because of its dubious identity after it was first discovered. It was initially interpreted as a bat, but has since been more accurately identified as a mole.

Mystipterus one of the earliest known moles.  By comparing the fossils that have been found to those of modern kinds of moles, paleontologists have predicted that Mystipterus would not have resembled the more specialized moles, with their enlarged front limbs for digging.  Rather it was most similar to moles in the genus Uropsilus, which are more generalized.  The common name for this group is the shrew-moles, since they in many ways resemble shrews.  It may have even had a long, trunk-like nose, like some shrews have.  

Jaw and teeth from Mystipterus featured in the 2023 paper, by Korth Et al. referenced below.

Like its modern relatives, Mystipterus likely spent most of its time underground, possibly coming out at night to hunt. It may also have been a strong swimmer in life, like many modern moles and shrews are, especially since the rocks its bones were found in indicate it would have inhabited a wet environment with lots of slow-moving rivers and streams.  Since it was so small, it would have needed to avoid predators, especially while above ground, like the early canid, Hesperocyon, whos bones were found in the same area as Mystipterus'.

References

Korth, W. W.; Boyd, C. A.; Emry, R. J. (2023). "Additional small mammals from the Oligocene Brule Formation (Whitneyan) of southwestern North Dakota". Paludicola. 14 (2): 57–74.