[Tallguy]

Ummmm... Continental Drift?...

[KarlInOhio]

Ummmm... Continental Drift?...

That was my first reaction too, but the article says: "When Svalbard was hot, 55 million years ago, the islands were also closer to the North Pole."

[verum ago]

Ummmm... Continental Drift?...

best I can tell going over maps, animations of continental positions, and texts, it appears Scandinavia was in nearly (maybe as little as ±5 to 10° latitude, but I'm not confident in that estimate at all) the same position then it was today, but rotated such that's long axis was in a roughly E-W direction, and squashed in closer to the continent. I'm going to see if I can't find some better information.
Also, sniffing around online it appears that Hippopotami were in fairly widespread in Europe as recently as less than 2MYA and as at least as far north as the british Isles; the ones in Africa also seem to do fine in zoos in colder climates as well.