If this is due to a common ancestor, or to the unusual mode of locomotion used by these animals (graviportal and plantigrade) remains a mystery to be seen. However, Gaudry (1909) himself established that Pyrotherium was sufficiently different from any other group of large mammals that it should have its own order, with no clear relation to other mammals.
The reason for the unique characteristics of these animals, whether due to a shared ancestor or their unusual locomotion (graviportal and plantigrade), remains unknown. However, Gaudry (1909) concluded that Pyrotherium was distinct enough from other large mammals to warrant its own order, with no clear connection to any existing mammal groups.