You do not have observable evidence of a dinosaur or a fossil forming. Therefore, you have no logical evidence that dinosaurs or dinosaur fossils exist as you have no firsthand evidence. Your argument of assimilation proves my point, as you assimilate through direct observations. Yet you have no direct observable evidence of a dinosaur or a fossil forming.
So according to your own assimilation argument, both are false.
How about mammoets Al-Fatihah ? Have they ever existed?
In this picture you see a human, an elephant and a mammoet.