I know the Book of Enoch is not considered divinely inspired but I do think the apocrypha could have some historical significance. I just recently started reading the book of Enoch and early on when it talks about the fallen angels mating with women and giving birth to the nephilim, it soon after says they began to sin against various animals as well. When I first read this I immediately thought of dinosaurs. If the fallen angels and humans gave birth to giant offspring could the fallen angels have mated with animals and given birth to dinosaurs and they were then wiped out in the flood as well?
I personally think dinosaurs were produced through genetic manipulation of some kind, and were wiped out in the flood along with the Nephilim. The Book of Enoch lends support to this view. But since it was written thousands of years after the fact, by someone only pretending to be Enoch, my opinion remains in the category of conjecture along with everything to be found in the Book of Enoch.