Вадим Дудченко
Администратор портала

A new species of Cretaceous hypercarnivorous ichthyosaur, Kyhytysuka sachicarum, has been described from a fossil found in Colombia.

Life reconstructions of Kyhytysuka sachicarum. Image credit: Dirley Cortés.

Kyhytysuka sachicarum swam in the Earth’s oceans during the Early Cretaceous epoch, some 130 million years ago.

Its well-preserved 1-m-long skull was uncovered in Colombia and initially assigned to a species called Platypterygius sachicarum.

“This animal evolved a unique dentition that allowed it to eat large prey,” said Dr. Hans Larsson, director of the Redpath Museum at McGill University.

“Whereas other ichthyosaurs had small, equally sized teeth for feeding on small prey, this new species modified its tooth sizes and spacing to build an arsenal of teeth for dispatching large prey, like big fishes and other marine reptiles.”

The big picture of ichthyosaur evolution is clarified with Kyhytysuka sachicarum, according to the team.

“We compared this animal to other Jurassic and Cretaceous ichthyosaurs and were able to define a new type of ichthyosaurs,” said Dr. Erin Maxwell, a researcher in the State Natural History Museum of Stuttgart.

“This shakes up the evolutionary tree of ichthyosaurs and lets us test new ideas of how they evolved.”

Kyhytysuka sachicarum comes from an important transitional time during the Early Cretaceous epoch.

At this time, the Earth was coming out of a relatively cool period, had rising sea levels, and the supercontinent Pangea was splitting into northern and southern landmasses.

There was also a global extinction event at the end of the Jurassic that changed marine and terrestrial ecosystems.

“Many classic Jurassic marine ecosystems of deep-water feeding ichthyosaurs, short-necked plesiosaurs, and marine-adapted crocodiles were succeeded by new lineages of long-necked plesiosaurs, sea turtles, large marine lizards called mosasaurs, and now this monster ichthyosaur,” said Dirley Cortes, a graduate student at the Smithsonian Tropical Research Institute.

“We are discovering many new species in the rocks this new ichthyosaur comes from.”

“We are testing the idea that this region and time in Colombia was an ancient biodiversity hotspot and are using the fossils to better understand the evolution of marine ecosystems during this transitional time.”

A paper on the findings was published in the Journal of Systematic Palaeontology.

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Dirley Cortés et al. Re-appearance of hypercarnivore ichthyosaurs in the Cretaceous with differentiated dentition: revision of ‘Platypterygius’ sachicarum (Reptilia: Ichthyosauria, Ophthalmosauridae) from Colombia. Journal of Systematic Palaeontology, published online November 22, 2021; doi: 10.1080/14772019.2021.1989507

 



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