Four odd ancient marsupials, Yalkaparidon, Groeberia, Vintana and Adalatherium, have a living ancestor: Dactylopsila

Short one today
as three graphics (Figs 1–3) tell the tale recently recovered by the large reptile tree (LRT, 2324 taxa) after DGS colors for Groeberia were revised to include more incisors, no canines and adjustments to the premaxilla/maxilla border.

Earlier these taxa
nested with the terrestrial interothere, Paedotherium. Now they nest with the phylogenetically more ancient arboreal petaurid possum Dactylopsila the “mammalian woodpecker” not far from its placental 2 counterpart, the aye-aye, Daubentonia from Madagascar and Middle Jurassic multituberculates, like Megaconus.

Earlier interatheres moved into the Placentalia – Ungulata in the LRT.

Systematics can be difficult. Sometimes it takes awhile to get to know who’s in and who’s out especially when starting from scratch.

Note the exposure of the long incisor roots
in Groeberia (Fig 3) compared to the same morphology in Yalkaparidon (Fig 2). Also note the pasting of the squamosal to the lateral side of the jugal, migrating from its original dorsal position.

Beck et al 2013 described Yalkaparidon
and mentioned similarities to Dactylopsila, but did not include Dactylopsila, Vintana, Adalatherium and Groeberia in their phylogenetic analysis.

Dactylopsila trivirgata 
(Gray 1858) is the extant striped possum, earlier closely related to the sugar glider, Petaurus and the marsupial lion, Thylacoleo. Now basal to taxa listed above, but still close to sugar gliders. It is an arboreal marsupial the size and proportions of a placental squirrel, but with a prehensile tail. The fourth finger is elongated and used to extract beetles and caterpillars from tree bark (as in the placental 2 aye-aye, Daubentonia (Fig 4). This omnivore also eats leaves, fruit and small vertebrates. The extinct placental Apatemys, has similar teeth.

Soligo 2005 wrote,
“Implications for the interpretation of suggested convergences between the aye-aye, the diprotodont marsupial Dactylopsila palpator and the early Tertiary apatemyid genus Heterohyus are discussed.”

Transitional taxa in the LRT do not share these manus proportions despite their relatively close phylogenetic proximity to one another – at present.

Groeberia pattersoni
((Patterson 1952;  MMP 738, Simpson 1970; Simpson and Wyss 1999, Eocene and Oligocene). Simpson and Wyss considered Groeberia close to diprotodontians (wombats). The LRT more or less supports that nesting as Groeberia nests with Vintana, another former enigma, both within the marsupials, but on a separate branch from wombats, closer to extant Dactylopsila (Fig 1).

This novel hypothesis of interrelationships
suggests several hypotheses for the restoration of the missing parts in all taxa pictured here (Figs 1–3). If not novel, please provide a citation so I can promote it here.

References
Archer M, Hand S and Godthelp H 1988. A new order of Tertiary zalambdodont marsupials. Science 239(4847):1528-1531.
Burmeister CV 1888. Relaciónde un viaje a la Gobernaciónde Chubut. Anales del Museo Nacional de Buenos Aires 3:175–252,
Cerdeño E and Bond M 1998. Taxonomic Revision and Phylogeny of Paedotherium and Tremacyllus (Pachyrukhinae, Hegetotheriidae, Notoungulata) from the Late Miocene to the Pleistocene of Argentina. Journal of Vertebrate Paleontology 18(4): 799-811.
Chimento NR, Agnolin  FL and Novas FE 2015. The bizarre ‘metatherians’ Groeberia and Patagonia, late surviving members of gondwanatherian mammals. Historical Biology: An International Journal of Paleobiology. 27 (5): 603–623.
doi:10.1080/08912963.2014.903945
Krause DW, Hoffmann S, Wible JR, Kirk EC, and several other authors 2014. First cranial remains of a gondwanatherian mammal reveal remarkable mosaicism. Nature. online. doi:10.1038/nature13922. ISSN 1476-4687.
Krause DW et al. 2014. Vintana sertichi (Mammalia, Gondwanatheria) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology Memoir 14. 222pp.
Patterson B 1952. Un nuevo y extraordinario marsupial deseadiano. Rev Mus Mun Cienc NatMar del Plata. 1:39–44.
Simpson GG 1970. Addition to the knowledge of Groeberia (Mammalia, Marsupialia) from the mid-Cenozoic of Argentina. Breviora 362:1-17.
Soligo C 2005. Anatomy of the hand and arm in Daubentonia magagascareiensis: a functional and phylogenetic outlook. Folia Primatol (Basel) 76(5):262-300.
doi: 10.1159/000088034.

wiki/Striped_possum – Dactylopsila trivirgata
wiki/Vintana
wiki/Groeberia
wiki/Adalatherium
wiki/Yalkaparidon

Source: https://pterosaurheresies.wordpress.com/2024/09/19/four-odd-ancient-marsupials-yalkaparidon-groeberia-vintana-and-adalatherium-have-a-living-ancestor-dactylopsila/