First amphibious ichthyosaur discovered, filling evolutionary gap

November 5, 2014, UC Davis
This illustration shows what a newly discovered amphibious ichthyosaur may have looked like when it was alive some 248 million years ago. Credit: Stefano Broccoli/University of Milan

The first fossil of an amphibious ichthyosaur has been discovered in China by a team led by researchers at the University of California, Davis. The discovery is the first to link the dolphin-like ichthyosaur to its terrestrial ancestors, filling a gap in the fossil record. The fossil is described in a paper published in advance online Nov. 5 in the journal Nature.

The represents a missing stage in the evolution of ichthyosaurs, marine reptiles from the Age of Dinosaurs about 250 million years ago. Until now, there were no fossils marking their transition from land to sea.

"But now we have this fossil showing the transition," said lead author Ryosuke Motani, a professor in the UC Davis Department of Earth and Planetary Sciences. "There's nothing that prevents it from coming onto land."

Motani and his colleagues discovered the fossil in China's Anhui Province. About 248 million years old, it is from the Triassic period and measures roughly 1.5 feet long.

Unlike ichthyosaurs fully adapted to life at sea, this one had unusually large, flexible flippers that likely allowed for seal-like movement on land. It had flexible wrists, which are essential for crawling on the ground. Most ichthyosaurs have long, beak-like snouts, but the amphibious fossil shows a nose as short as that of land reptiles.

Its body also contains thicker bones than previously-described ichthyosaurs. This is in keeping with the idea that most who transitioned from land first became heavier, for example with thicker bones, in order to swim through rough coastal waves before entering the deep sea.

Fossil remains show the first amphibious ichthyosaur found in China by a team led by a UC Davis scientist. Its amphibious characteristics include large flippers and flexible wrists, essential for crawling on the ground. Credit: Ryosuke Motani/UC Davis

The study's implications go beyond evolutionary theory, Motani said. This animal lived about 4 million years after the worst mass extinction in Earth's history, 252 million years ago. Scientists have wondered how long it took for animals and plants to recover after such destruction, particularly since the extinction was associated with global warming.

"This was analogous to what might happen if the world gets warmer and warmer," Motani said. "How long did it take before the globe was good enough for predators like this to reappear? In that world, many things became extinct, but it started something new. These reptiles came out during this recovery."

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9 comments

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Shabs42
4.4 / 5 (7) Nov 05, 2014
Whoa, ten hours and we don't have any of the anti-evolution cranks coming out yet? Hard evidence can be hard to dispute. Guess I'll go have to read some astrophysics articles to get my dose of crazy today.
tritace
Nov 05, 2014
This comment has been removed by a moderator.
Whydening Gyre
5 / 5 (3) Nov 06, 2014
Zeph - that was great! Five to you..:-)
Torbjorn_Larsson_OM
3.5 / 5 (8) Nov 06, 2014
Ah, a true transational fossil!

But can we please lay off the religious magic references on a science thread? The leader of the catholic sect is as much a creationist as those that post different lies here.

They still have a magic man behind the curtain, and doesn't accept the human lineage or the natural emergence of the universe. (Claim that there were a bottleneck of a single human breeding pair, because their myth says so, despite we now know it is lie - the bottleneck was ~ 12 000 humans; claim that humans have a magic 'soul'; et cetera; open and known lies, such as that they are not creationists in the first place.)
Whydening Gyre
5 / 5 (2) Nov 06, 2014
Ah, a true transational fossil!

But can we please lay off the religious magic references on a science thread? The leader of the catholic sect is as much a creationist as those that post different lies here.

They still have a magic man behind the curtain, and doesn't accept the human lineage or the natural emergence of the universe. (Claim that there were a bottleneck of a single human breeding pair, because their myth says so, despite we now know it is lie - the bottleneck was ~ 12 000 humans; claim that humans have a magic 'soul'; et cetera; open and known lies, such as that they are not creationists in the first place.)

C'mon, TL... You didn't get the sarcasm in his comment and link post?
Anda
not rated yet Nov 09, 2014
Nice finding.
Reminds the actual evolutionary state of seals and the like.
TheGhostofOtto1923
4 / 5 (4) Nov 09, 2014
does anyone know how fossils are formed?
Well according to you and your book, they were all formed during the great flood, which leads us to the uncomfortable conclusion that if all those millions of extinct species were alive together beforehand in sufficiently large reproductive groups, that 1000s of species would be occupying the same niches at the same time and worse, the world would be knee deep in dead and dying animal flesh.

Does this really make sense to you?
Vietvet
4.2 / 5 (5) Nov 09, 2014
@Ren82
You ARE an uneducated troll.
Mike_Massen
3 / 5 (2) Nov 13, 2014
Ren82 claimed with sarcasm but proves he doesnt have maths/physics knowledge
Some researchers must find an transient species and they found amphibian. Then they must find Higgs boson and they found Higgs boson. Currently they looking for dark matter, and I'm sure that you they will find it. The same with dark energy. That is the way to invent a new reality in which they are filling more comfortable.
All above have maths to deal with as part of the route to evidence, plus in biological terms we NOW know mechanism by which changes to species occur - Darwin didn't know, we do - its called DNA & its reliance on DNA base pairs.

One of which comes from early earth's atmosphere of ammonia, becomes formamide leading to Guanine. Does progression stop there Ren82, is there any evidence other base pairs (also amines) could NOT have occurred given ALL the base materials were present & are STILL present ?

Evidence Ren82, your god forced Moses to write a book ?

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