Gene study shows sabertooths were no pussy cats

Science News Article | Reuters.co.uk

I remember reading, several years ago, that sabertooth cats had appeared and disappeared throughout the fossil record, and that it happenened in cycles of somewhere around 30-40,000 years. This lead me to hypothesize (mistakenly, I guess ..) that the large cats retained the genes for "saber-toothedness", even as the gene expression went cold over long periods of time.
I even thought that this might be a form of gene conservation involving the regions called " Junk DNA " that currently don't seem to code for genes.
It also interested me, as to whether the cyclical nature, might have something to do with Ice Ages, Magnetic Pole Reversal, and/or the rise of MegaFauna.
Ice Ages could lead to a vast lowering of ocean levels, which in turn would expose and create huge grasslands ... which would lead, over time to the larger and larger .. eventually MegaFauna ... whose predators might evolve ... say, to be SaberToothed.....
Since they say that the sabertooth went extinct, then it must have been a morphological characteristic that arises in different species of cats, over time due to changes in their niches.