See 211, Decemviri sacris faciundis; Bardt 30. Papus may have succeeded M. Aemilius Lepidus who assumed this priesthood in 211. (Broughton MRR I)
M. Valerius Messalla succeeded L. Aemilius Papus. Liv. 42.28.10-13. See Münzer, Gent. Val. 51, no. 53. Bardt (30) holds that his son, Consul 161, may have been the successor (cf. Münzer, Gent. Val. 52, no. 54). (Broughton MRR I)