T-Rex was created by the Fallen Angels, mixing DNA:
Jasher 4-18
18 And their judges and rulers went to the daughters of men and took their wives by force from their husbands according to their choice, and the sons of men in those days
took from the cattle of the earth, the beasts of the field and the fowls of the air, and taught the mixture of animals of one species with the other,
in order therewith to provoke the Lord; and God saw the whole earth and it was corrupt, for all flesh had corrupted its ways upon earth, all men and all animals.