A few years ago, I noticed some interesting presentations by geology undergraduates at the Keck Symposium – see 4 papers online here – describing fossils from the Miocene and Pliocene (both well after the Cretaceous) in the Arctic. Here’s a tree from the Pliocene – which is not “hundreds of millions” of years ago, but the period immediately preceding the very cold Pleistocene.
One of the paper specifically reports on Alaska temperature over the Tertiary (post-dinosaurs: the last 50 million years or so)
In Alaska (paleolatitude of 60°N) the MAT dropped from ca. 11° to 4° C between 12 and 13 Ma with concomitant changes in the vegetation (Wolfe 1997).
I’m sure that any geology undergrad could make an excellent reading list for an inquisitive Secretary.