What animal has the longest skull and the shortest spine?

The Sperm Whale (Physeter Macrocephalus) (Cachalot) is the animal with the largest skull in the world (both in general and aquatically).

The African Bush Elephant (Loxodonta Africana) is the largest-skulled terrestrial animal in the world.

The extinct aquatic animal with the largest skull would probably be either a Mosasaurus Hoffmannii or a Carcharodon Megaladon.

The Titanoceratops Ouranos is the extinct terrestrial animal with the largest skull.