Proterix
Proterix is an extinct genus of erinaceid mammal from the Late Oligocene to the Early Miocene of North America. Ecology
Proterix was most likely a burrowing insectivore. The original reference suggests reduced limbs may be possible, due to the unusually high number of lumbar vertebrae, but cautions that conclusions must be reserved until a complete skeleton is found. This proposal was exaggerated in a popular science book by Dougal Dixon, which speculated that it may have been a limbless mammal with an armored head. Though very little of the post-cranial skeleton has been found, this situation is typical for mammals and not an indicator of unusual anatomy. References

Oligocene mammals of North America
Miocene mammals of North America
Erinaceidae
Fossil taxa described in 1903