I reckon they died out around the time of Noe's flood.
And as for them bieng fossilised don't worry about that, you see scientists will tell you that bones take millions of years to fossilise but this is incorrect.
There are cat skeletons at Lightning Ridge in Australia which have opalised in the few short years since europeans have been here.
Previously scientists thought that bones took millions of years to opalise.
The answers are all there, it's just that this modern evil society will do and say just about ANYTHING no matter how preposterous to deny the existence of God.