An apparent eye-witness account is found in Aristotle’s Historia Animalium.
Strabo makes reference to an eyewitness account of a dead sea creature sighted by Poseidonius on the coast of the northern Levant. He reports the following: “As for the plains, the first, beginning at the sea, is called Macras, or Macra-Plain. Here, as reported by Poseidonius, was seen the fallen dragon, the corpse of which was about a plethrum [100 feet] in length, and so bulky that horsemen standing by it on either side could not see one another; and its jaws were large enough to admit a man on horseback, and each flake of its horny scales exceeded an oblong shield in length. “(Geography, book 16, chapter two, paragraph 17) The creature was seen by Poseidonius, a Philosopher, sometime between 130 and 51 BC.