Peter Costello drew attention to this mosaic in In Search Of Lake Monsters and surmised that it represented the same kind of Longnecked Sea-serpent that witnesses continued seeing and which were the basis for many reports of Lake Monsters worldwide.He noted that it could not be a reconstruction of a fossil animal because it contained features which occurred in the reports and which could not possibly be inferred from fossils. Later critical response included the assertion that it and the similar depictions below must have been made to account for fossils. Fossils do not indicate ears or horns, manes or humps on the back (often called "Coils" and thought of as being a long body thrown up into twists and turns)
(I have pointed this out to both Tyler Stone and Jay Cooney)
Illustrations of "Cetus" (Ketos in Greek) from 1st-2nd Century mosaics at Rome. The "Cetus" (Now used to mean "Whale" but it is evidently an even older IndoEuropean root meaning "a Disturbance or a Shaking",ie, "That which disturbs the waters from below"). The Greek story of Perseus had him rescuing a Phoenician princess from a Cetus (Ketos), and it is the name of one of the constellations as a result. The constellation is traditionally represented as a long-necked sea monster.