Really? The Book of Giants also says that the Nephilim created a legion of monsters via mixing DNA of different animals. I am in no doubt at all that this is how dinosaurs came into existence.

Read:

The two hundred angels choose animals on which to perform unnatural acts, including, presumably, humans.

1Q23 Frag. 1 + 6 [ . . . two hundred] 2donkeys, two hundred asses, two hundred . . . rams of the] 3flock, two hundred goats, two hundred [ . . . beast of the] 4field from every animal, from every [bird . . . ] 5[ . . . ] for miscegenation DNA mixing [ . . . ]

The outcome of the demonic corruption was violence, perversion, and a brood of monstrous beings. Compare Genesis 6:4.
4Q531 Frag. 2 [ . . . ] they defiled [ . . . ] 2[ . . . they begot] giants and monsters [ . . . ] 3[ . . . ] they begot, and, behold, all [the earth was corrupted . . . ] 4[ . . . ] with its blood and by the hand of [ . . . ] 5[giant's] which did not suffice for them and [ . . . ] 6[ . . . ] and they were seeking to devour many [ . . . ] 7[ . . . ] 8[ . . . ] the monsters attacked it.

4Q532 Col. 2 Frags. 1 - 6 2[ . . . ] flesh [ . . . ] 3al[l . . . ] monsters [ . . . ] will be [ . . . ] 4[ . . . ] they would arise [ . . . ] lacking in true knowledge [ . . . ] because [ . . . ] 5[ . . . ] the earth [grew corrupt . . . ] mighty [ . . . ] 6[ . . . ] they were considering [ . . . ] 7[ . . . ] from the angels upon [ . . . ] 8[ . . . ] in the end it will perish and die [ . . . ] 9[ . . . ] they caused great corruption in the [earth . . . ] [ . . . this did not] suffice to [ . . . ] "they will be [ . . . ]