Ugh.

Had a major brainfart.

I wrote:
 > Biggest mammalian land carnivore looks like a variety of sabre-tooth
 > tiger, 'Smilodon populator' that topped out at 440kg.

That ignores the polar bear, but is otherwise correct.

There were larger bear-like creatures, the amphicyonids or "bear-dogs"
that lived in the Eocene to Pleistocene epochs that may have got up to
600kg. They transitioned to plantigrade gait (and likely omnivorous
diets) by the time they got that big.

Rob O'Connor