Thalattoarchon saurophagis: Marine Predators.
Size: 28 feet (8.6 meters) long.
Time Period: The Anisian Stage of the Middle Triassic.
Locale: The Favret Formation of Nevada in the United States.
Name: The generic name means “lord of the sea” in reference to the predatory nature of the animal. The specific name means “serpent-eater,” because the animal may have eaten its own relatives.
Even though the dinosaurs ruled the land during the Mesozoic, the sea was one place that they never truly conquered. Even today, seagoing birds are far from the top of the food chain, mostly due to huge aquatic predators. A trend of evolution was the tendency of some groups to return to the water even though their ancestors had once crawled out of a primeval ocean themselves. During the Mesozoic, many sea reptile groups appeared, from plesiosaurs like Liopleurodon to seagoing lizards like Plotosaurus to marine crocodiles like Dakosaurus (see my post on the very same animal for more). One other group that is slightly less well-known is the ichthyosaurs, a shame considering how cool they were. These fish-mimics had their beginnings in the Triassic Period, and finally met their end during the Early Cretaceous for reasons yet unknown (but possibly due to the appearance of aforementioned seagoing lizards). One of the earlier species of ichthyosaur may also be the sea’s first macropredatory animal (an animal capable of seizing animals as big as it was and eating them).
Thalattoarchon is the name of this ichthyosaur, whose primary difference from later relatives like Temnodontosaurus and Opthalmosaurus is its snout. Whereas you might find conical, unserrated teeth for grabbing fish and cephalopods in the snouts of most ichthyosaurs, Thalattoarchon had large, thin teeth with two cutting edges and smooth crowns. These blade-like teeth were probably helpful in the seizing of other prey, and though their surfaces aren’t serrated like a Tyrannosaurus’s, they resemble the teeth of such evolutionary success stories as the mosasaurs and pliosaurs. These animals were also kings of the ocean in their own times.
Since not very much skeletal material of Thalattoarchon is actually known, its appearance must be inferred. Like most primitive ichthyosaurs, it probably had an elongated, eel-like body and a barely-developed tail fin to aid with swimming. It was found in the same area as its look-alike, the ichthyosaur Cymbospondylus, which it differed from by having a head twice the size of Cymbospondylus’s head relative to its body. In fact, Thalattoarchon may have even evolved its lethal dentition to kill and eat other ichthyosaurs, but until actual evidence of this is found (coprolites, bones of other animals found with Thalattoarchon) no conclusion can be reached.
Another thing that Thalattoarchon indicates was how life was recovering after the Permian-Triassic extinction, which wiped out over 90% of all life on the planet. Specialized macropredatory creatures like this big ichthyosaur only appear when communities of animal are diverse and well-established. If one lived in a community that was not like this, it would simply starve due to lack of food. Since Thalattoarchon lived only 8 million years after the great extinction, the marine life of the world had to have bounced back and specialized considerably in order to accommodate such specialized predators. Only species that were truly resilient would have survived to create these new environments, alluding to the possibility of Permian ancestors of groups like the ichthyosaurs that we haven’t uncovered yet.
In conclusion, Thalattoarchon is the first huge badass marine predator described in 2013. Not only is it a huge marine apex predator, but one of the first. It fills in a bit of information about ichthyosaur evolution and how a devastated world bounces back after a major extinction, like the kind that not even the ichthyosaurs could avoid millions of years after this sharp-toothed predator ruled the seas.