This Prehistoric Ocean Was a Living Nightmare

85 million years ago, a shallow inland sea split North America clean in half — and filled itself with the most dangerous collection of predators ever assembled in a single body of water. This is the Western Interior Seaway. This is Hell's Aquarium. In this video, we walk through every major predator that ruled this ocean: from mosasaurs that ate other sea monsters for lunch, to a shark that hunted flying animals from below, to the heaviest invertebrate ever to exist on Earth — all sharing 150 feet of warm, sunlit tropical water at the same time. And we end with something that evolved in North American waters after the asteroid — something that might be even stranger than everything that came before it. 💬 JOIN THE DISCUSSION Tylosaurus or Mosasaurus — you're in the water, one of them is coming. Which one, and why? Drop your answer in the comments. Best responses get called out in the next video. 📚 REFERENCES / LITERATURE Everhart, M.J. (2005). Oceans of Kansas: A Natural History of the Western Interior Sea. Indiana University Press. Everhart, M.J. et al. — Multiple papers on mosasaur distribution and stomach contents via oceanofkansas.com Konishi, T. et al. (2012). New soft tissue preservation in Platecarpus (Squamata, Mosasauridae). Journal of Vertebrate Paleontology. ReSide, J.B. & Cobban, W.A. — Western Interior Seaway paleogeography studies, USGS. Schwimmer, D.R. (2002). King of the Crocodylians: The Paleobiology of Deinosuchus. Indiana University Press. Fröbisch, N.B. et al. — Plesiosaur vertebral records and Elasmosauridae systematics. Shimada, K. (1997). Paleoecology of Cretoxyrhina mantelli from the Niobrara Chalk. Journal of Vertebrate Paleontology. Friedman, M. (2012). Xiphactinus and the ecology of Late Cretaceous large predatory fishes. 🔍TAGS western interior seaway, hell's aquarium, mosasaurus, tylosaurus, prehistoric ocean, cretaceous sea monsters, deinosuchus, cretoxyrhina ginsu shark, xiphactinus fish within a fish, parapuzosia giant ammonite, plesiosaurs elasmosaurus, squalicorax crow shark, prehistoric predators, north america prehistoric, cretaceous period animals, sea monsters documentary, prehistoric earth, mosasaur vs tylosaurus, ancient ocean predators, paleontology documentary, Mr Owl Science, prehistoric sea documentary, western interior sea predators, cretaceous apex predators, platecarpus mosasaur, tusoteuthis giant squid, prognathodon, clidastes, albertonectes, ptychodus shark #️⃣ HASHTAGS #WesternInteriorSeaway #HellsAquarium #Mosasaurus #Tylosaurus #PrehistoricOcean #SeaMonsters #Paleontology #Cretaceous #Deinosuchus #PrehistoricEarth #Xiphactinus #Plesiosaur #GinsuShark #Cretoxyrhina #AncientOcean #NaturalHistory #ScienceDocumentary #MrOwlScience #Parapuzosia #PrehistoricPredators