Necrolestes patagonensis (Ameghino 1891; early Miocene, 16mya; YPM PU 15065, 15384, and 15699) has been argued about for over a hundred years. Originally it was described as the only known extinct placental “insectivore” from South America and allied to Chrysochloris, the extant golden mole from Africa.
Unfortunately, as time went Saban 1954 considered Necrolestes a palaeanodont (Ernanodon was previously considered one). Patterson 1958 considered it a borhyaenoid metatherian. Asher et al. 2007 looked at several candidates and could not make a firm conclusion. Ladevèze et al. 2008 supported metatherian affinities. Goin et al. 2008 also could not be specific with regard to a closest known sister taxon.
The latest paper on the subject,
Rougier et al. 2012, reported, “earlier studies leaned toward placental affinities and more recent ones endorsed either therian or specifically metatherian relationships.” Ultimately they nested Necrolestes with Cronopio (Fig. 4) which they considered a non-therian mammal. That is closer. They considered an earlier Van Valen 1988 statement inspired, “…the enigmatic Miocene genus Necrolestes, usually thought to be a marsupial, is [conceivably] a late surviving Gondwantherian pantothere.” That is incorrect.
In the LRT Necrolestes nests with the extant marsupial mole, Notoryctes and the Middle Jurassic marsupial mole, Docofossor. All three have five or more molars and a long list of other synapomorphies. |
