The serpentine whale from Eyrie is based on the basilosaurus. Within the novel, the serpentine whales lurk off the southern coast of Luminaire, feeding upon local schools of fish and migrating with them as the seasons change.
Fisherfolk still tell the tale of the time a serpentine whale became trapped in the shallows near Swan’s Rest and wrecked several villages before being dispatched by a massive crane opinicus and his petrel gryphon second-in-command.
In the real world, basilosaurus, despite the name and most paleoart, is a whale and not a dinosaur. It was long, snake-like, and huge. Wikipedia has a nice collection of bones and interpretations to look over.