Cronopio dentiacutus (Rougier et al. 2011, early Late Cretaceous, 98 mya; MPCA PV 454 and others; 2 cm est. skull length) was originally described as a dryolestid mammal. Tradtionally and here dryolestids nest outside of the Theria, basal to Didelphis. Here Cronopio nests with Acristatherium. This shrew-like mammal had a long rostrum and extraordinary saber-tooth canines. In dorsal and palatal view the rostrum was pinched then expanded.

Acristatherium yanensis (Hu et al., 2010; early Cretaceous (Aptian), 125 mya, IVPP V15004) was originally described as a tiny eutherian mammal. By contrast, in the large reptile tree Acristatherium nests with Cronopio, a taxon not originally tested.

Bradshaw D and Bradshaw F 2012. The physiology of the honey possum, Tarsipes rostratus, a small marsupial with a suite of highly specialised characters: a review. J Comp Physiol 182(4):469-89. doi: 10.1007/s00360-011-0632-9.

Hu Y-M, Meng J, Li C-K and Wang YQ 2016. New basal eutherian mammal from the Early Cretaceous Jehol biota, Liaoning, China. Proceedings of the Royal Society B.
doi:10.1098/rspb.2009.0203 Published online

Rougier GW, Apesteguía S and Gaetano LC 2011. Highly specialized mammalian skulls from the Late Cretaceous of South America. Nature. 479: 98–102.

Tomes PZS 1863. A small marsupial from Ecuador, named Hyracodon fuliginosus. Proceedings of the Zoological Society, London: 50–51.

wiki/Cronopio
wiki/Acristatherium