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Ancient Big-Snouted Marine Reptile Discovered

Artist's illustration of mosasaur
Tatsuya Shinmura

Approximately 145 million years ago, a new apex predator began stalking the world’s oceans: the mosasaurs. Sometimes growing up to 50 feet long (longer than a T-Rex), these fierce marine reptiles’ fossils have been found on every continent. Now, a new species has been added to the collection.

The find was described by master’s student Catie Strong from the University of Alberta (UA), who came upon the fossil in a phosphate mine in Morocco.

“Morocco is an incredibly good place to find fossils, especially in these phosphate mines,” Strong said. “Those phosphates themselves reflect sediments that would have been deposited in marine environments, so there are a lot of mosasaurs there.”

While dozens of species of mosasaurs have already been described, Strong’s find—named Gavialimimus almaghribensis—differs in that it has an extremely long snout, which is part of a skull measuring almost 10 feet long. She believes this gave it an advantage in an aquatic world where there was lots of competition for food.

“Its long snout reflects that this mosasaur was likely adapted to a specific form of predation, or niche partitioning, within this larger ecosystem, “Strong explained. “For some species, these adaptations can be very prominent, such as the extremely long snout and the interlocking teeth in Gavialimimus, which we hypothesized as helping it to catch rapidly moving prey.

Mosasaur skull fossil
Catie Strong

 

As an example of another mosasaur species with a unique adaptation, Strong points to the Globidens simplex, a find described by the UA lab last year. This reptile had short round teeth that were likely suited for crushing rather than tearing, which would help it get through the shells of prey.

Strong’s mosasaur, however, had interlocking teeth, resembling those appearing in modern-day crocodiles and alligators.

“Not all of the adaptations in these dozen or so species are this dramatic, and in some cases, there may have been some overlap in prey items, but overall there is evidence that there’s been diversification of these species into different niches,” Strong noted. “This does help give another dimension to that diversity and shows how all of these animals living at the same time in the same place were able to branch off and take their own paths through evolution to be able to coexist like that.”

The find has been described in the Journal of Systematic Palaeontology.