Full fossils from an infinite shark that lived alongside the dinosaurs reveal essential details about this enigmatic predator — together with it being an historic relative of the nice white shark.
The sharks, from the genus Ptychodus, had been first found within the mid-eighteenth century. Descriptions of this genus had been largely based mostly on their tooth — which could possibly be practically 22 inches (55 centimeters) lengthy and 18 inches (45 cm) large, and had been tailored for crushing shells — present in quite a few marine deposits relationship to the Cretaceous interval (145 million to 66 million years in the past).
With out the flexibility to look at a totally intact specimen, researchers had hotly debated what the shark’s physique form would possibly appear to be — till now.
“The invention of full Ptychodus specimens is actually thrilling as a result of it solves one of the putting enigmas in vertebrate paleontology,” lead writer Romain Vullo, a researcher at Géosciences Rennes, informed Stay Science in an electronic mail.
In a research printed Wednesday (April 24) within the journal Proceedings of the Royal Society B: Organic Sciences, researchers have described full fossils of the shark found in limestone quarries in Nuevo León, northeastern Mexico. Its define was nonetheless totally preserved, and its physique form suggests it hunted sea turtles — which may clarify its extinction round 76 million years in the past because it was competing with different animals that ate the identical prey.
The specimens “present an beautiful preservation,” as a result of they had been deposited in a quiet space with no scavengers, Vullo stated. “The carcasses of animals had been quickly buried in a gentle lime mud earlier than being totally disarticulated.”
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Evaluation of the fossils reveals this massive predator belonged to the mackerel shark group (Lamniformes), which incorporates nice whites (Carcharodon carcharias), mako, and salmon sharks. It grew to round 33 ft (10 meters) lengthy and is understood for its huge, grinding tooth, that are not like these we see in sharks immediately.
It was extensively believed that Ptychodus consumed invertebrates from the seabed — the traditional kin of clams and mussels. However the brand new fossils problem that, revealing that this historic shark had a streamlined physique form, indicating it was a fast-swimming pelagic predator. “The newly found fossils from Mexico point out that Ptychodus appeared just like the residing porbeagle shark,” Vullo stated, however with “distinctive grinding dentition.”
This new info has led the researchers to consider it preyed on massive ammonites — a kind of crustacean with a tough shell — and sea turtles.
“Ptychodus occupied a particular ecological area of interest in Late Cretaceous seas,” Vullo stated, as a result of it was the one pelagic shark that was tailored to consuming hard-shelled prey resembling turtles. This will clarify why it died out round 10 million years earlier than the extinction occasion that ended the Cretaceous interval. “Towards the top of the Cretaceous, these massive sharks had been seemingly in direct competitors with some marine reptiles (mosasaurs) focusing on the identical prey,” he stated.