Updated December 30, 2016 and August 17, 2017:
Vincelestes nests in the Marsupialia now that several marsupials have been added to the LRT.
Earlier and earlier…
Earlier we looked at Jurassic origins for the first half of the mammal family tree. Vincelestes (Bonaparte 1986, MACN-N 04) is an Early Cretaceous (130 mya) taxon that nests at the base of the Carnivora in the large reptile tree (764 taxa).
Bonaparte (2008) reports, “The topology suggests that the early Cretaceous mammal from Patagonia, Vincelestes, is nested within a clade comprising ‘other Gondwanan mammals’, separated from Laurasian taxa. It is proposed that the tribosphenic condition may have developed first amongst taxa on Pangea, before the separation of Laurasia and Gondwana.”
Wikipedia reports, “Although not the direct ancestor of therians, Vincelestes is important because it gives us an idea of what the ancestor of both placental and marsupial mammals might have looked like, and also gives an indication of when these mammals may have originated.”
Digimorph reports, “The species highlighted here, Vincelestes neuquenianus, is the sister lineage of therians. the cheek teeth of Vincelestes have a “reversed triangle” occlusal pattern that closely approximates the fully tribosphenic pattern of therians, an innovation that enables them to process food more thoroughly.”
the hyperenlarged canines and short rostrum. Derived from a sister to Eomaia, the basalmost therian, Vincelestes was a sister to Oxyaena, not far from saber-toothed Thylacosmilus. Molars were not carnassial in shape, but able to process by cutting and grinding. Nine individuals are known.
Bonaparte JF 1986. Sobre Mesungulatum houusayi y nuevos mamíferos Cretácicos de Patagonia, Argentina [On Mesungulatum houssayi and new Cretaceous mammals from Patagonia, Argentina]. Actas del IV Congreso Argentino de Paleontología y Biostratigrafía 2:48-61.
Bonaparte JF 2008. On the phylogenetic relationships of Vincelestes neuquenianus. Historical Biology 20(2):
Rowe T 1993. Phylogenetic systematics and the early history of mammals; pp. 129-145 in F. S. Szalay, M. J. Novacek, and M. C. McKenna (eds.), Mammalian phylogeny, Springer-Verlag, New York.