So I was looking through some “older” papers and found this one by Rigby et al. (1987)(pdf attached). They were looking at some of the rock formations specifically members of the Hell Creek Formation. In one area, they have a lot of river deposits from before and after the K-T boundary. In one of the river deposits from the Paleocene as dated by pollen fossils, contains ungulate mammal fossils and some dinosaur teeth specifically ceratopsian and theropod teeth as far as I understood. They recognize that the dinosaur fossils could have been eroded from the bank and fallen in but the fossils aren’t weathered like they should have been and the river wasn’t the right kind that would rework sediments. I’m not sure I believe their arguments but what do you guys think?
Rigby-et-al_1987_Paleocene-dinos.pdf