I’ve been dragging my heels with these prehistoric creature posts, but with “Jurassic World” just around the corner, I decided to get off my buns and post about one of my all time favorites: mosasaurs.
Mosasaurs ruled the oceans of the Cretaceous Period of the Mesozoic Era of Earth’s history, biting sharks in half while T-Rex was doing the same with anatosaurs. A close relative of modern-day monitor lizards and snakes (more on this in a minute) mosasaurs were the dominant marine predators for the last 20 million years of the Dinosaur Age, an age where the seas included plesiosaurs and Ginsu sharks–25 foot long ancestors of the great white and named for the Ginsu knife. Evolving from small lizards that lived in swamps and lakes to avoid dinosaurs, and later made the transition to oceans, mosasaurs ruled their environment with a number of different weapons, not least of which was their size, which ranged from roughly the size of a Labrador, to the 60 foot long Mosasaurus.
But what did such titanic beasts even feed on? Luckily for mosasaurs, everything during this time was just too big. Sea birds as tall as a man, carnivorous fish the size of motor boats, sea turtle that dwarfed life-rafts, and of course the sharks and plesiosaurs I mentioned earlier, mosasaurs had their pick of what to eat. Mosasaurs tracked their prey with two keen weapons, the first of which were pressure sensors in their snouts. Like modern day crocodiles and Cretaceous Era Spinosaurus (the star of Jurassic Park III) mosasaurs had pockets of nervous tissue in their snouts that allowed them to detect the pressure waves made by all swimming creatures. Their second weapon was a forked tongue that, like those of their modern snake and monitor lizard cousins, could be used to track scents, even underwater.
We can make the assumption that mosasaurs had these forked tongues by looking at their modern relatives, and we certainly know who those are. By looking at the skeletons of mosasaurs, as well as soft tissue imprints–which show small, triangular scales like those of snakes–we can see the similarities they possess to snakes and monitors. Not just that, but the lower jaw of a mosasaur was double-hinged, just like those of modern snakes, which mean that they could move their bottom jaws forward-and-back as well as up-and-down. You’d think that meat hook teeth and Satan’s own mandibles would be enough, but mosasaurs also possessed a second set of teeth in the upper jaw which would hold prey, as well as shred it to pieces, as it used its double-hinged snappers to drag up to four feet of flesh down its gullet at a time. Pay attention to the inside of the mosasaur’s jaws in the Jurassic World trailer and you’ll see those devilish teeth yourself.
I mentioned soft tissue deposits, which, as you may be aware, rarely fossilize. Well, remains in Harrana, Jordan (which was underwater at the time) were so well preserved that scientists were able to study the softer, squishier bits that don’t often survive millions of years of being buried in the dirt. This is how they know what the mosasaurs’ scales were like, how they know that the organs were arranged much like those of modern whales, and how they know that mosasaur had a tail like a shark’s. This design being in modern sharks and fish is no accident, it optimizes how much water is displaced with each stroke from the tail, allowing more efficiency for a swimming creature. While things are more ambiguous for the smaller species, larger specimens like the Mosasaurus itself were unlikely to pursue prey long distances. Like modern great whites, they likely patrolled populous waters until they found a good spot before laying in wait for something to swim too close, tagging their chosen prey with a great burst of power.
With the depletion in fish stalks that occurred after the KT Event–otherwise known as the meteor-based bitch slap that rebooted life on planet Earth–larger predators simply couldn’t continue; they simply couldn’t survive on the smaller fish left behind. The implications that it took an event of cosmic proportions to send these beasts into extinction speaks volumes of their rule. Even had dinosaurs died out and left the mosasaurs alive, the world would be much different; there would be no whales, dolphins, porpoises, seals or sea lions or walruses for one thing. They wouldn’t be able to compete, mammals simply couldn’t take to the seas, which raises more implications about man’s place in a world like this. Even if we evolved at all, we wouldn’t be able to conquer the globe like we have today. Fishing would be too dangerous an enterprise with 60-foot sea beasts patrolling the best places, early man would not have been able to travel as far afield across the oceans in rafts and small boats. Much of our current success is a result of our ability to harness the resources of the oceans, the domain of the mosasaurs.