Sinonyx jiashanensis (Zhou et al. 1995; late Paleocene, 55 mya; 28 cm skull length) was also originally considered a mesonychid. Here Sinonyx nests with Andrewsarchus as an anagalid. It had 11 teeth (x4) including 4 blunt molars and a tall sagittal crest over the narrow cranium.

Wikipedia reports that scientists once thought of Sinonyx as a whale ancestor, but now consider artiodactyls close to hippos as whale ancestors. Both suffer from taxon exclusion.

Arctocyon primaevus (Blainville 1841, Gould and Rose 2014; YPM VP 021233; Paleocene, 60 mya) was long and widely considered a primitive plantigrade ungulate condylarth procreodi placental. In the LRT Arctocyon nests within the mesonychds not far from Sinonyx. Litolophus (below) is related.

Blainville HM 1841. Osteographie et description iconographique des Mammiferes récentes et fossiles (Carnivores) 1, 2 Paris.

Bai B, Wang Y-Q and Meng J 2010. Early Eocene chalicothere Litolophus with hoof-like unguals. Journal of Vertebrate Paleontology 31(6):1387-1391.

Colbert EH 1934. Chalicotheres from Mongolia and China in the American Museum. Bulletin of the American Museum of Natural History 47(3):353–387.

Gould FDH and Rose KD 2014. Gnathic and postcranial skeleton of the largest known arctocyonid ‘condylarth’ Arctocyon mumak (Mammalia, Procreodi) and ecomorphological diversity in Procreodi. Journal of Vertebrate Paleontology 34(5):1180-1202.

Zhou X, Zhai R, Gingerich PD and Chen L 1995. Skull of a new mesonychid (Mammalia, Mesonychia) from the Late Paleocene of China. Journal of Vertebrate Paleontology 15(2):387-400.

wiki/Sinonyx
wiki/Arctocyon