Xenocranium: now a marsupial mole in the LRT
According to Wikipedia – Xenocranium
“Xenocranium (“strange skull”) is an extinct monotypic genus of placental mammal from extinct paraphyletic subfamily Epoicotheriinae within extinct paraphyletic family Epoicotheriidae in extinct order Palaeanodonta, that lived in North America during the late Eocene. Xenocranium pileorivale was a highly specialized animal that was convergent with the talpids, golden moles and marsupial mole. It possesses many traits indicative of the lifestyle of a subterranean burrower, including small eyes, an upturned snout, muscular arms.”
Figure 1. Xenocranium here compared to Ottoryctes. These tiny taxa are related to marsupial moles, like Notoryctes, in the LRT. Skulls are shown life size on a 72dpi monitor.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/xenocranium.skull2-588-1.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/xenocranium.skull2-588-1.jpg?w=584″ class=”size-full wp-image-92307″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/xenocranium.skull2-588-1.jpg” alt=”Figure 1. Xenocranium here compared to Ottoryctes. These tiny taxa are related to marsupial moles, like Notoryctes, in the LRT. Skulls are shown life size on a 72dpi monitor.” width=”584″ height=”520″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/xenocranium.skull2-588-1.jpg?w=584&h=520 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/xenocranium.skull2-588-1.jpg?w=150&h=134 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/xenocranium.skull2-588-1.jpg?w=300&h=267 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/xenocranium.skull2-588-1.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 1. Xenocranium here compared to Ottoryctes. These tiny taxa are related to marsupial moles, like Notoryctes, in the LRT. Skulls are shown life size on a 72dpi monitor.
After a bit of housekeeping
in the large reptile tree (LRT, 2338 taxa) tiny Xenocranium (Fig 1) now nests with marsupial moles, like Notoryctes, and Ottoryctes (Fig 1), which also has those inflated squamosals (magenta) substituting for inflated auditory bulla, perhaps.
‘Inflated squamosals’ are not scored in the LRT. That’s because no other tested taxa have them. Instead, the LRT scored the usual list of measurable traits.
Xenocranium pileorivale
(Colbert, 1942; Emry and Rose 1983; Late Oligocene) was originally considered a burrowing edentate, then a pangolin. Here it nests with Ottorynctes and Notoryctes, both marsupial moles. Post-crania includes large claws, interpreted for burrowing.
Figure 1. Notoryctes skull from copyright Digimorph.org, used with permission. New DGS colors applied to teeth and cranium.
” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/notoryctes-marsupial-mole_skull588.jpg?w=240″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/notoryctes-marsupial-mole_skull588.jpg?w=584″ class=”size-full wp-image-92303″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/notoryctes-marsupial-mole_skull588.jpg” alt=”Figure 1. Notoryctes skull from copyright Digimorph.org, used with permission. New DGS colors applied to teeth and cranium.” width=”584″ height=”730″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/notoryctes-marsupial-mole_skull588.jpg?w=584&h=730 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/notoryctes-marsupial-mole_skull588.jpg?w=120&h=150 120w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/notoryctes-marsupial-mole_skull588.jpg?w=240&h=300 240w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/04/notoryctes-marsupial-mole_skull588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />
Figure 1. Notoryctes skull from copyright Digimorph.org, used with permission. New DGS colors applied to teeth and cranium.
Notoryctes typhlops
(Stirling 1888, 1891; extant; 16 cm in length) is the marsupial mole. Once classified as a monotreme, here it nests with the marsupial Anebodon and Ottoryctes in the large reptile tree. Notoryctes is blind with eyes reduced to vestigial lenses. It has no external ears. Four molars are present. The pouch opens toward the tail and contains two teats. Several neck vertebrae are fused.The clavicle is robust as an anchor for digging muscles. The tail verts are quite robust, especially for a mole. Tiny epipubes are present. A cloaca is present a trait otherwise seen in monotremes and tenrecs. The forelimb has transformed to support the two large digging claws of digits 3 and 4.
These changes reflect recent revisions of the teeth of related taxa that also lack canines.
That means the golden mole, Chrysochloris, no longer nests with marsupial moles in the LRT. Now it nests between the recently added hedgehog, Hemiechinus and extinct Necrolestes. So Chrysochloris, the golden mole, had hedgehog ancestors.
Correcting past mistakes is what leads to present and future discoveries.
This revision appears to be a novel hypothesis of interrelationships.
If not, please provide a citation so I can promote it here.
References
Colbert EH 1942. Edentate from the Oligocene of Wyoming. Notulae Naturae. Academy of Natural Sciences, No. 109.
Emry RJ and Rose KD 1983. Extraordinary Fossorial Adaptations in the Oligocene Palaeonodonts Epoicotherium and Xenocranium (Mammalia). Journal of Morphology 175(1):33–56.
wiki/Xenocranium
wiki/Ottoryctes – not yet posted
wiki/Notoryctes
Source: https://pterosaurheresies.wordpress.com/2025/04/06/xenocranium-now-a-marsupial-mole-in-the-lrt/
