4 am in the morning, 1967, A winter season was caused in September, by an unidentified object falling from the sky.

someone had claimed they saw a creature.

What they saw:

The description was, the body of a furry humanoid, The head of a raven,the eyes of hell, the horns of the devil, the wings of the lost angels, the claws of a thirsty animal, the legs of a bovine, the muscles of a god, the complementary colors of a burning red and a dried out green.

A dreadwalker did not evolve from a bird, but a bird caught a disease, floating in the air.

And the first dreadwalker was in formation, soon to become a complete creature of its own.

No longer a deformed raven.
A creature completely designed in the depths of hell.