Early Palaeocene Alcidedorbignya compared to the extant marsupial Monodelphis

Quick one today.
These two skulls side-by-side (Fig 1) indicate extant marsupial. Monodelphis domestica, and early Palaeocene, Alcidedorbignya, may be more closely related than anyone thought. Together they create yet another separate origin for the placenta among placental mammals in the LRT. So this topic is getting both complicated and exciting.

This recovery was like turning a page and starting a new chapter.

Hopefully this will resolve all remaining issues.

Figure 1. Above: the one-vagina marsupial Monodelphis domestica. Below: the Early Palaeocene basal pantodont, Alcidedorbignya ” data-image-caption=”

Figure 1. Above: the one-vagina marsupial Monodelphis domestica. Below: the Early Palaeocene basal pantodont, Alcidedorbignya

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/09/alcidedorbignya-monodelphis588.jpg?w=153″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/09/alcidedorbignya-monodelphis588.jpg?w=523″ tabindex=”0″ role=”button” class=”size-full wp-image-88606″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/09/alcidedorbignya-monodelphis588.jpg” alt=”Figure 1. Above: the one-vagina marsupial Monodelphis domestica. Below: the Early Palaeocene basal pantodont, Alcidedorbignya” width=”584″ height=”1144″ />

Figure 1. Above: the extant one-vagina marsupial Monodelphis domestica. Below: the Early Palaeocene basal pantodont, Alcidedorbignya. Note the striking similarity of the nasal (pink) shapes along with the rest of the traits. Seeing the two skulls together allows one to get an understanding of the evolution from one to another Bauplan.

In evolution no two specimens are identical.
Therefore, no two species and no two genera are identical. In the LRT two slightly dissimilar taxa share more traits with each other than with any other tested taxa. The software does the lumping and splitting.

In their description of Alcidedorbignya
de Muizon et al 2015 mentioned Monodelphis with regard to the nasal turbinates.

Monodelphis and Alcidedorbignya were compared earlier
here in July 2022, but they did not nest together then as they do now. That’s when Monodelphis was considered the last common ancestor of all placentals. That hypothesis has changed in the last few weeks, following Wortman 1902.

References
de Muizon C de & Marshall LG 1992. Alcidedorbignya inopinata (Mammalia: Pantodonta) from the early Paleocene of Bolivia: phylogenetic and paleobiogeographic implications. Journal of Paleontology 66 (3): 499-520.
deMuizon C, Billet G, Argot C, Ladeveze S and Goussard F 2015. Alcidedorbignya inopinata, a basal pantodont (Placentalia, Mammalia) from the early Palaeocene
of Bolivia: anatomy, phylogeny and palaeobiology. Geodiversitas 87(4):397-634.
Halliday TJD, Upchurch P and Goswami A 2015. Resolving the relationships of Paleocene placental mammals. Biological Reviews. 92 (1): 521–550.
Matthew WD 1906. The Osteology of Sinopa, a Creodont Mammal of the Middle Eocene.
Proc. U. S. Nat. Mus., Vol. XXX, pp. 203-233, pl. XVI.
Wortman JL 1901-1903. Studies of Eocene Mammalia in the Marsh Collection, Peabody Museum. Am. Jour. Sci. 11:333–348.

wiki/Placentalia
wiki/Alcidedorbignya
wiki/Monodelpis

Three origins for placental reproduction in mammals

Wortman 1902 was first: Three origins for placental mammals hypothesis

Ectoconus and Pantolambda also move very close to the base of the Placentalia