A new species of hypercarnivorous ichthyosaur identified

A new species of hypercarnivorous ichthyosaur from the Cretaceous, Kyhytysuka sachicarumwas described from a fossil found in Colombia.

life reconstructions of Kyhytysuka sachicarum. Image credit: Dirley Cortes.

Kyhytysuka sachicarum swam in the Earth’s oceans during the early Cretaceous, about 130 million years ago.

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

“This animal developed unique dentition that allowed it to eat large prey,” said Dr. Hans Larsson, director of McGill University’s Redpath Museum.

“While other ichthyosaurs had small teeth of equal size to feed on small prey, this new species altered the size and spacing of its teeth to build an arsenal of teeth to dispatch large prey, such as large fish and other marine reptiles.

The overview of ichthyosaur evolution is clarified with Kyhytysuka sachicarumaccording to the team.

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

“This upends the evolutionary tree of ichthyosaurs and allows us to test new ideas about how they evolved.”

Kyhytysuka sachicarum comes from an important transition period during the Lower Cretaceous epoch.

At this time, the Earth was emerging from a relatively cool period, sea levels were rising, and the supercontinent Pangea was separating into northern and southern landmasses.

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

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

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

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

A paper on the conclusions was published in the Journal of Systematic Paleontology.

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Dirley Cortes et al. Reappearance of hypercarnivorous ichthyosaurs in the Cretaceous with differentiated dentition: revision of ‘Platypterygius’ sachicarum (Reptilia: Ichthyosauria, Ophthalmosauridae) from Colombia. Journal of Systematic Paleontology, posted on November 22, 2021; doi: 10.1080/14772019.2021.1989507

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