"Behold now behemoth, which I made with thee; he eateth grass as an ox. Lo now, his strength is in his loins, and his force is in the navel of his belly. He moveth his tail like a cedar: the sinews of his stones are wrapped together. His bones are as strong pieces of brass; his bones are like bars of iron." Job 40:15-18
This would be an ideal description from a different point of view of a dinosaur. A cedar is a big tree, and anything that has a tail that big, yeah, that's a formidable animal.
I too believe that the flood killed these animals, and not a comet, that's all speculation. There's a reason God did not allow these animals to continue on with mankind.