During the Classical period, the common words for "Shark" and "Whale" were used in a generic sense to denote any kind of sea monster. I have good representational proof that one kind of Sea Monster or Sae Dragon referred to was a large crocodile, but the most common depictions showed a more Plesiosaurian-shaped creature. The fairly substantial forequarters with large pectoral flippers often stand in contrast to the elongated and coiling tail section, but that was the usual way of showing humps. This sort of sea monster was commonly illustrated in the stories of Jonah and the Whale or Perseus and Andromeda. Such depictions continue on into the Byzantine period. The earlier blog example showing Jason is often grouped in together with these. I don't know why many cultures depict plesiosaur-shaped creatures swallowing human prey because it seems pretty well certain that their throats are too narrow to allow such a thing.
Here are several examples spanning many centuries. The tail is ofen shown as three-pronged. which may be a conventionalized way of showing two hind flippers and a tail together.
Manes are often shown but are usually of the short and spiky sort.
The general effect is like a marine Sirrush. Two horns are often shown on the head, and sometimes the creature sticks out a long tongue also. The profile of the head and neck are conventionalised but can be recognised when shown separately at small size on coins for example.
Another, older example from Greece and illustrating the story of Pereus and Andromeda. Versions of these Sea Monster depictions done in this style can be found from 1000 BC up to about AD 1500, at which time they begin appearing in bestaries and they start to merge into the more recognisable, more modern Sea-Serpent reports.
Best Wishes, Dale D.
Multiple Coils Mean Multiple Humps in Sighting.