Ichthyosaurs, Dinosaurs’ Marine Cousins Killed By Climate Change

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The ichthyosaurs, predatory “fish-reptiles”, fell victim to climate change and slowed evolution during their 150 million year life as the dinosaur/shark of the ocean according to new research.

Global environmental changes spelled doom for the ichthyosaurs

While dinosaurs were roaming the earth, the ichthyosaurs were ruling the oceans. For about 157 million years ending roughly 90 million years ago, these large-eyed, shark-like killing machines were patrolling and stalking out their quarry in the depths of the ocean.

Vertebrate paleontologist, Dr. Valentin Fischer of the University of Oxford, led the study and published his findings in the journal Nature Communications today. The doctor pointed out that the extinction was a mystery to he and his colleagues for years as the ichthyosaurs were well-suited to their lives in the ocean. The extinction of the ichthyosaurs occurred about 30 million years ahead of the mass dinosaur extinction that the end of the Cretaceous period 66 million years ago.

Prior to the group’s findings it was postulated that the extinction was not caused by climate change, but rather competition for food from other marine reptiles and fish or a decline in their primary food supply, squid-like belemnites.

“These theories were at odds with the recent understanding of the ichthyosaur fossil record, which suggests they were actually quite diverse prior to their extinction,” he said.

“We wanted to analyse this extinction thoroughly and look for possible alternative drivers.”

What were those drivers?

The group believes that fluctuations in the sea level and water temperatures were responsible for the creatures’ demise among other factors.

“It seems that a large part of the marine biosphere was affected by an event or a series of rapid events that profoundly modified marine ecosystems,” he added.

“These events coincided with profound climatic changes: fast-moving continents, intense volcanism, ice-free poles and episodes of anoxia (lack of oxygen) on the sea floor.”

The team, with its findings, did not dismiss other possibilities for the extinction of the ichthyosaur including competition, dwindling food supplies and other factors.

Because of the diversity of the ichthyosaurs, the researchers essentially ruled out a lack of evolutionary prowess among the ichthyosaurs and pinned their demise on a continued changing of the climate.

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