This is an addendum to Jeletzky's (1962) study of Danian dinosaur-bearing rocks and the Mesozoic-Cenozoic boundary. All adequately sampled North American Late Cretaceous mammalian local faunas are made up of multituberculates, placentals, and marsupials. An increase in the relative abundance of placentals occurred at least locally before the extinction of the dinosaurs. The records of Scaphites and other marine organisms in the upper part of the Lance Formation are probably the result of erratic introduction of contemporaneous animals during deposition.