Mongolochelys efremovi (Khosatzky 1997; Suzuki and Chinzorig 2010; Campanian, Late Cretaceous, 70mya; PIN 551-459) was originally considered a basal sister to Meiolania but here nests with Chubutemys.

Chubutemys copelloi (Gaffney et al. 2007, Sterli et al. 2013; Early Cretaceous, 112mya, 0.6m, (2 ft) in length; MEPF-PV 1236) was considered a basal meiolaniform, but here Meiolania is the basalmost hard-shelled turtle and Chubutemys nests with Mongolochelys. The shell was remarkably thin.

Gaffney ES, Rich TH, Vickers-Rich P, Constantine, A, Vacca R and Kool L 2007. Chubutemys, a new Eucryptodiran turtle from the Early Cretaceous of Argentina, and the relationships of the Meiolaniidae. American Museum Novitates 3599, 1–35.

Hutchinson JH, Jenkins FA Jr. and Meeker LJ 1987. Modern Turtle Origins; The Oldest Known Cryptodire. Science 237 (4812): 289–291. doi:10.1126/science.237.4812.289. PMID 17772056.

Khosatzky LI 1997. Big turtle of the Late Cretaceous of Mongolia. Russian Journal of Herpetology 4(2):148-154.

Sterli J, Fuente MS, Umazano AM 2013. New remains and new insights on the Gondwanan meiolaniform turtle Chubutemys copelloi from the Lower Cretaceous of Patagonia, Argentina. Gondwana Research (2013). doi:10.1016/j.gr.2013.08.016.

Suzuki S, Chinzorig T 2010. A catalog of Mongolochelys collected by the HMNS–MPC Joint Paleontological Expedition. Hayashibara Museum of Natural Sciences Research
Bulletin 3: 119–131.

wiki/Chubutemys