Machimosaurus Rex: Largest Marine Crocodile Discovered


The biggest ever marine crocodile ever found has turned up in the Tunisian desert. The humongous of a prehistoric predator grew to over 30 feet long and weighed three tons.

Paleontologists have dubbed the new species Machimosaurus rex and describe it Monday in the journal Cretaceous Research.

Although the recovered remains are fragmentary, enough remained in the 120-million-year-old rock to identify the reptile as the largest known member of a peculiar lineage of crocodiles that spent their lives almost entirely at sea.

“This is a neat new discovery from a part of the world that hasn’t been well-explored for fossils,” says University of Edinburgh paleontologist Stephen Brusatte, who was not involved with the new study.

The fossils, including a skull and a smattering of other bones, were discovered by Federico Fanti of the University of Bologna in Italy and colleagues with support from the National Geographic Society.


A reconstruction of Machimosaurus rex based on the fossil bones found (white) shows its size compared with a human.

Scientists are awaiting the discovery of a more complete skeleton to figure out exactly how large Machimosaurus rex was.

While not as large as some of its later, distant relatives that lived in freshwater, that makes Machimosaurus rex the biggest ocean-dwelling member of the crocodile family tree.

The carnivore’s teeth may hint at what it fed on in the ancient ocean. “Machimosaurus rex had stocky, relatively short and rounded teeth,” Fanti says, “and a massive skull capable of a remarkable bite force.” This cluster of features leads Fanti to suggest that the croc was a generalist hunter that took a variety of prey, including large marine turtles.

“It would likely have been something of an ambush predator, hanging around in shallow water hunting turtles and fishes and maybe waiting for some land animals to come a little too close to the shore,” Brusatte adds.

For scientists, the most important aspect of Machimosaurus rex isn’t so much its size as when it lived.


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