Tylosaurus, a formidable marine reptile that once dominated ancient oceans, ultimately vanished from Earth’s waters. Its extinction offers insight into the broader patterns of life and extinction events.
Unveiling the Tylosaurus
Tylosaurus was a massive predatory marine lizard, part of an extinct group called mosasaurs. These creatures were distant relatives of modern-day snakes and monitor lizards, adapted for aquatic life. Growing up to 45 to 50 feet long, Tylosaurus had powerful jaws with two rows of pointed, conical teeth, making it an apex predator. Its elongated snout also gave the creature its name.
This reptile thrived in the warm, shallow inland seas covering much of North America during the Late Cretaceous period, approximately 92 to 66 million years ago. The Western Interior Seaway served as its primary hunting ground. Fossil evidence shows Tylosaurus was an opportunistic hunter, with stomach contents revealing a diet of fish, turtles, other marine reptiles, and even smaller mosasaurs and plesiosaurs.
The Great Extinction Event
Tylosaurus went extinct around 66 million years ago, during the Cretaceous-Paleogene (K-Pg) extinction event. This event marks the boundary between the Cretaceous and Paleogene periods, fundamentally reshaping life on Earth. Scientific consensus points to a massive asteroid impact, estimated between 6 to 9 miles wide, as the primary trigger for this widespread extinction.
The asteroid struck Earth in what is now the Yucatán Peninsula in Mexico, creating the Chicxulub crater. The impact unleashed immense energy, equivalent to about 100 million megatons of dynamite, generating global shockwaves. This strike immediately caused widespread fires and colossal tsunamis.
Beyond the immediate devastation, the impact propelled vast quantities of dust, ash, and sulfur aerosols into the atmosphere. This atmospheric debris blocked sunlight for an extended period, leading to a prolonged “impact winter” that halted photosynthesis in plants and plankton. The disruption of the food chain, combined with global cooling and ocean acidification, created environmental conditions many species, including Tylosaurus, could not endure.
Beyond the Tylosaurus: Other Casualties
The K-Pg extinction event was not isolated to Tylosaurus; it was a mass extinction that eliminated approximately three-quarters of Earth’s plant and animal species. This event saw the complete disappearance of all non-avian dinosaurs, which had dominated terrestrial ecosystems for millions of years.
Marine environments also suffered significant losses. Alongside mosasaurs like Tylosaurus, other large marine reptiles such as plesiosaurs and ichthyosaurs vanished. Many invertebrate groups, including ammonites and rudists, also went extinct. The event profoundly impacted plankton populations, which form the base of marine food webs, leading to widespread ecosystem collapse.