Xenocranium pileorivale lived during the late Eocene, about 35 million years ago, in what is now the Midwestern and Mountain states regions of the USA.
Despite its very mole-like appearance, this little mammal was a member of an extinct lineage known as palaeanodonts — and its closest living relatives are actually pangolins.
Around 15cm long (~6″), Xenocranium was highly adapted for a subterranean burrowing lifestyle, with an upturned shovel-shaped snout bearing a pad of thickened skin, and short powerful limbs with large digging claws. Its eyes were very reduced, functionally blind, and may not have even been visible in life. Its sense of hearing was also specialized for the sort of low-frequency sounds that carry well through the ground.
It was probably a head-lift digger, using upward motions of its snout and downward strokes with its forelimbs to excavate tunnels while foraging for worms and underground insects.
References:
- Hopkins, Samantha SB, and Edward Byrd Davis. “Quantitative morphological proxies for fossoriality in small mammals.” Journal of Mammalogy 90.6 (2009): 1449-1460. https://doi.org/10.1644/08-MAMM-A-262R1.1
- Rose, Kenneth D., and Robert J. Emry. “Extraordinary fossorial adaptations in the Oligocene palaeanodonts Epoicotherium and Xenocranium (Mammalia).” Journal of Morphology 175.1 (1983): 33-56. https://doi.org/10.1002/jmor.1051750105
- Wikipedia contributors. “Xenocranium” Wikipedia, 31 Dec. 2025, https://en.wikipedia.org/wiki/Xenocranium