Shortly before an asteroid changed the course of history, the shallow waters of present-day Morocco were bubbling with top predators whose list has just grown. A team of paleontologists has announced the discovery of a new mosasaur that has developed a hunting strategy reminiscent of that of modern sea snakes.
Mosasaurs (Mosasauridae) are a family of reptiles that populated the Earth’s oceans during the Cretaceous Period. Their diversity peaked during the Maastrichtian era, 72 to 66 million years ago. Depending on the species, these predators were between 3.5 and 18 meters long. The one newly identified in Morocco (thanks to the analysis of two almost complete skulls) fit roughly in the center of these estimates with a body length of up to about eight meters.
Hunt with the tongue
Named Pluridens Serpent, this mosasaur had developed long, slender jaws with many small hooked teeth allowing it to catch small prey such as fish and squid. Compared to related mosasaur species, it also featured smaller eyes, which suggests poor vision.
On the other hand, his muzzle showed dozens of openings for the nerves, suggesting that he was sensitive enough to hunt by detecting tiny changes in water pressure in low light conditions.
“Generally, when animals develop small eyes, it is because they are more dependent on other senses.“, Notes Dr Nick Longrich of the Milner Center for Evolution at the University of Bath.
We could then draw a parallel with modern sea snakes which wave their forked tongues underwater to detect chemical signals allowing their prey to be stalked. “If he did not use the eyes then it was very likely that he was using the tongue to hunt, like snakes“, Confirms Dr Longrich.
An exceptional ecosystem
While most terrestrial ecosystems support only one or two large carnivores today, paleontological evidence suggests that this was the case in the past as well. In this sense, the seas of the Maastrichtian era are an anomaly. Back then, off what is now Morocco, the shallow waters were indeed occupied by an array of predatory species, some of which were terrifyingly large.
A snake represents for example the thirteenth species of mosasaur from Maastrichtian Morocco. All have not evolved simultaneously, but these numbers are still remarkable. Indeed, these waters were also home to plesiosaurs, large sharks and other crocodilians, above which hovered many pterosaurs.
“The diversity of these fossils is simply astonishing. Far from declining, mosasaurs seemed have reached their peak just before their extinction“, Concludes Dr Longrich. Indeed, nothing can prepare you for an asteroid.
You will find the details of this work in the journal Cretaceous research.