A Change of Guard

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Tuesday, 24 May 2016

Strange Fossil Hints at Life After Mass Extinction

Strange Fossil Hints at Life After Mass Extinction
May 23, 2016 

by Discovery News

Shown is Sclerocormus parviceps, a newly described marine reptile.

Da-yong Jiang

A fossil from a newly discovered animal that didn’t look like it was supposed to has given scientists a window into the evolutionary period just after the worst mass extinction event the planet has ever known.

The new species, an ichthyosaur named Sclerocormus parviceps, was a marine reptile dating to the Lower Triassic, and it looked nothing like other ichthyosaurs scientists have studied.

Ichthyosaurs were marine reptiles that lived at the same time as Earth’s earliest dinosaurs. Most had dolphin-like forms – strong tail fin, long telltale snout and sleek body. But the new animal had a stubby snout and a long tail — sans the big fin at the end.

Stranger still, ichthyosaurs typically had ample teeth for catching food, but Sclerocormus parviceps had no teeth at all. The researchers think its snout was built for sucking in food like a needle drawing blood.

The fossil dates to the time just after the Permian-Triassic event, which took out nearly all marine species and the vast majority of terrestrial vertebrates. Scientists had thought it was slow going for marine reptiles rebounding from that period, with evolutionary processes unfolding slowly.

However, the new fossil, looking nothing like its ancient relatives, challenges those notions.

“Sclerocormus tells us that ichthyosauriforms evolved and diversified rapidly at the end of the Lower Triassic period,” said study co-author Olivier Rieppel, of The Field Museum, in a statement.

“We don’t have many marine reptile fossils from this period,” Rieppel added, “so this specimen is important because it suggests that there’s diversity that hasn’t been uncovered yet.”

Rieppel said the new reptile offered a peek at real-world evolution in action.

“Darwin’s model of evolution consists of small, gradual changes over a long period of time, and that’s not quite what we’re seeing here,” he said. “These ichthyosauriforms seem to have evolved very quickly, in short bursts of lots of change, in leaps and bounds.”

The museum biology curator thinks the find can help us better understand what life does when it needs to rebound.

“We’re in a mass extinction right now. Not one caused by volcanoes or meteorites but by humans,” Rieppel said. “While the extinction 250 million years ago won’t tell us how to solve what’s going on today, it does bear on the evolutionary theory at work. How do we understand the recovery and rebuilding of a food chain, of an ecosystem? How does that get fixed, and what comes first?”

Rieppel is part of an international team of scientists that worked on the study, which has been published in the journal Scientific Reports.


Anonymous said...

just wondering how come so far there has been no dinosaurs bones found in cambodia , considering that ancient khmers had seen them -- a carving relief of what looks like a dinosaur [ stegosaurus ] at Ta Prohm temple had puzzled many people .

Anonymous said...

Cambodia is a low-lying country formed by the Mekong river. Thus there is little up-lifting rocks to fossilize dinosaurs.