WFS

Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, India

Fossil wood park maintained by geological survey of India at Tamilnadu

Cretaceous fossil sites india

Fossils in rack:-Cyad

Fossils in rack:-echiniderms

Fossils in rack:-Rastellum sp

Pre-historic seabed, Cretaceous period

volcanoes may be much closer than thought

December 10th, 2014

Riffin

Credit: Virginia Tech

Traditional thought holds that hot updrafts from the Earth’s core cause volcanoes, but researchers say eruptions may stem from the asthenosphere, a layer closer to the surface.

Credit: Virginia Tech

A long-held assumption about the Earth is discussed in today’s edition of Science, as Don L. Anderson, an emeritus professor with the Seismological Laboratory of the California Institute of Technology, and Scott King, a professor of geophysics in the College of Science at Virginia Tech, look at how a layer beneath the Earth’s crust may be responsible for volcanic eruptions.

The discovery challenges conventional thought that volcanoes are caused when plates that make up the planet’s crust shift and release heat.

Instead of coming from deep within the interior of the planet, the responsibility is closer to the surface, about 80 kilometers to 200 kilometers deep — a layer above the Earth’s mantle, known as the as the asthenosphere.

“For nearly 40 years there has been a debate over a theory that volcanic island chains, such as Hawaii, have been formed by the interaction between plates at the surface and plumes of hot material that rise from the core-mantle boundary nearly 1,800 miles below the Earth’s surface,” King said. “Our paper shows that a hot layer beneath the plates may explain the origin of mid-plate volcanoes without resorting to deep conduits from halfway to the center of the Earth.”

Traditionally, the asthenosphere has been viewed as a passive structure that separates the moving tectonic plates from the mantle.

As tectonic plates move several inches every year, the boundaries between the plates spawn most of the planet’s volcanoes and earthquakes.

“As the Earth cools, the tectonic plates sink and displace warmer material deep within the interior of the Earth,” explained King. “This material rises as two broad, passive updrafts that seismologists have long recognized in their imaging of the interior of the Earth.”

The work of Anderson and King, however, shows that the hot, weak region beneath the plates acts as a lubricating layer, preventing the plates from dragging the material below along with them as they move.

The researchers show this lubricating layer is also the hottest part of the mantle, so there is no need for heat to be carried up to explain mid-plate volcanoes.

“We’re taking the position that plate tectonics and mid-plate volcanoes are the natural results of processes in the plates and the layer beneath them,” King said.

Fossil hunters find skeleton of 40,000-year-old woolly mammoth in North Sea

December 9th, 2014

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Fossil hunters searching for ancient relics have found the skeleton of a 40,000-year-old woolly mammoth in North Sea. The team of archaeologists, salvagers and palaeontologists trawled the waters off the east coast of Britain at a depth of 100 feet. North Sea Fossils, who are based in Urk, Netherlands, include an expert they call “Mr Mammoth” and are in search of the remains of extinct animals in the dark depths. Bones of animals including woolly rhinos, Irish elks and parts of the male skeleton of an 11-foot tall woolly mammoth, including its skull and tusks, have all been brought up and collected. A prehistoric skull of a European bison, also known as a Wisent, was also discovered lying on the North Sea bed.

Carbon dating tests revealed the bones belonged to a mammoth that roamed the planet around 40,000 years ago.Markus Broch, who works at North Sea Fossils, said it is “extremely rare” to find and later assemble a complete mammoth skeleton.Mr Broch said: “During the Ice Age there was no sea between Holland and England and these great beasts roamed and died there.”That is why their bones are still found by boats fishing in the North Sea.

“My father-in-law, who is a fisherman, started collecting these bones at young age because he was fascinated by them, and has now assembled a very large collection “We started selling duplicates from his collection online some years ago, which went so well that our business have grown and grown.

“Most weeks we go to the fishing ports to meet the fishing vessels and buy the fossils they caught.”Sometimes we charter a boat of our own and go for special ‘fossil hunting’ expeditions.”Because we see so many fossils we work very closely with the leading experts in the field, such as Dick Mol, who is the world’s leading authority on mammoths.”We have assembled a number of complete skeletons of mammoths, something very few companies in the world can do.”

The skull of an adult male mammoth being fished up on the North Sea just off the coast of Rotterdam by Dutch fishermen

The salvagers have managed to piece together the entire mammoth skeleton after initially discovering the skull and tusks of the animal in 2012.

The firm travelled out to sea and recovered a stash of other mammoth fossils using deep sea trawler nets before piecing them together at their base in Urk.Other items found by the firm include parts of sabre-toothed tigers, the skull of a woolly rhino and the cranium of a reindeer.Mammoths were first described in 1799 by Johann Friedrich Blumenback, a German scientist.He gave the name Elephas primigenius to elephant-like bones found in Europe.

The bones belonged to the woolly mammoth which was later considered to be a distinct genus and renamed Mamuthus primigenus.The species found by North Sea Fossils were known to roam through parts of Central Europe around 40,000 years ago.

Source: An article in Telegraph

Turtles and dinosaurs: evolution of turtles

December 7th, 2014

Riffin

A team of scientists, including researchers from the California Academy of Sciences, has reconstructed a detailed “tree of life” for turtles. The specifics of how turtles are related — to one another, to other reptiles, and even to dinosaurs — have been hotly debated for decades. Next generation sequencing technologies in Academy labs have generated unprecedented amounts of genetic information for a thrilling new look at turtles’ evolutionary history. These high-tech lab methods revolutionize the way scientists explore species origins and evolutionary relationships, and provide a strong foundation for future looks into Earth’s fossil record.

Research results, appearing in Molecular Phylogenetics and Evolution, describe how a new genetic sequencing technique called Ultra Conserved Elements (UCE) reveal turtles’ closest relatives across the animal kingdom. The new genetic tree uses an enormous amount of data to refute the notion that turtles are most closely related to lizards and snakes. Instead, authors place turtles in the newly named group “Archelosauria” with their closest relatives: birds, crocodiles, and dinosaurs. Scientists suspect the new group will be the largest group of vertebrates to ever receive a new scientific name.

The UCE technique used in high-tech labs allowed scientists to move beyond years of speculation and place the Archelosauria group in its rightful place on the reptile tree of life. UCE has been available since 2012, yet scientists are just beginning to tap its potential for generating enormous amounts of genetic data across vertebrates.

“Calling this is an exciting new era of sequencing technology is an understatement,” says Brian Simison, PhD, Director of the Academy’s Center for Comparative Genomics (CCG) that analyzed the study’s massive amount of data. The CCG is a state-of-the-art facility composed of a sequencing lab, frozen DNA collection, and computing resources that serves as the Academy’s core genetic center. Established in the summer of 2008, the CCG continues to refine Academy research — including new turtle findings — on a global, evolutionary scale.

“In the space of just five years, reasonably affordable studies using DNA sequencing have advanced from using only a handful of genetic markers to more than 2,000 — an unbelievable amount of DNA,” adds Simison. “New techniques like UCE dramatically improve our ability to help resolve decades-long evolutionary mysteries, giving us a clear picture of how animals like turtles evolved on our constantly-changing planet.”

Major findings also resolve an evolutionary mystery surrounding softshell turtles — a bizarre group of scale-less turtles with snorkel-like snouts. Until now, studies linked softshell turtles with a smaller semi-aquatic group called mud turtles, despite the fact that softshells appear in the fossil record long before their mud-loving counterparts. The Academy’s study places softshells in a league of their own on the evolutionary tree, quite far removed from any turtle relatives. Their long independent history helps explain their striking looks as well as their ancient presence in the fossil record.

Study coauthor James Parham, PhD — Academy Research Associate, Assistant Professor of Geological Sciences at Cal State Fullerton, and turtle expert — says cutting-edge testing techniques bring a new level of clarity to more than two decades of his turtle research. With large amounts of data backing up each evolutionary branch on the turtle tree of life, scientists are able to compare their evolution not only across species, but also across each continent’s corresponding fossil records.

“I have been working on the evolutionary relationships of turtles for over 20 years using a variety of methods,” says Parham. “Fossils are essential for showing us what extinct turtles looked like, but also in letting us know when and where they lived in the past.”

Parham notes that studying turtle fossils — particularly the physical features of their bones — hasn’t always painted an accurate evolutionary picture of turtle relationships across continents and through time. “The turtle tree of life based on fossil turtle anatomy didn’t match up with the timing of their appearance in the fossil record, as well as their geography,” Parham says. “But the tree of life generated at the Academy’s CCG is consistent with time and space patterns we’ve gathered from the fossil record. These new testing techniques help reconcile the information from DNA and fossils, making us confident that we’ve found the right tree.”

Lava erupting on sea floor linked to deep-carbon cycle

November 25th, 2014

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Scientists from the Smithsonian and the University of Rhode Island have found unsuspected linkages between the oxidation state of iron in volcanic rocks and variations in the chemistry of the deep Earth. Not only do the trends run counter to predictions from recent decades of study, they belie a role for carbon circulating in the deep Earth.The team’s research was published May 2 in Science Express.

Elizabeth Cottrell, lead author and research geologist at the Smithsonian’s National Museum of Natural History, and Katherine Kelley at the University of Rhode Island’s Graduate School of Oceanography measured the oxidation state of iron, which is the amount of iron that has a 3+ versus a 2+ electronic charge, in bits of magma that froze to a glass when they hit the freezing waters and crushing pressures of the sea floor. Due to the high precision afforded by the spectroscopic technique they used, the researchers found very subtle variations in the iron-oxidation state that had been overlooked by previous investigations.

Molten magma erupted onto the seafloor freezes to glass that contains clues to its origin in Earth’s deep interior and ancient past (field of view ~1 cm). Volcanic glasses like this one may reveal a link between Earth’s oxidation state and the deep carbon cycle.
Credit: Glenn Macpherson and Tim Gooding

The variations correlate with what Cottrell described as the “fingerprints” of the deep Earth rocks that melted to produce the lavas — but not in the way previous researchers had predicted. The erupted lavas that have lower concentrations of 3+ iron also have higher concentrations of elements such as barium, thorium, rubidium and lanthanum, that concentrate in the lavas, rather than staying in their deep Earth home. More importantly, the oxidation state of iron also correlates with elements that became enriched in lavas long ago, and now, after billions of years, show elevated ratios of radiogenic isotopes. Because radiogenic isotopic ratios cannot be modified during rock melting and eruption, Cottrell called this “a dead ringer for the source of the melt itself.”

Carbon is one of the “geochemical goodies” that tends to become enriched in the lava when rocks melt. “Despite is importance to life on this planet, carbon is a really tricky element to get a handle on in melts from the deep Earth,” said Cottrell. “That is because carbon also volatilizes and is lost to the ocean waters such that it can’t easily be quantified in the lavas themselves. As humans we are very focused on what we see up here on the surface. Most people probably don’t recognize that the vast majority of carbon — the backbone of all life — is located in the deep Earth, below the surface — maybe even 90 percent of it.”

The rocks that the team analyzed that were reduced also showed a greater influence of having melted in the presence of carbon than those that were oxidized. “And this makes sense because for every atom of carbon present at depth it has to steal oxygen away from iron as it ascends toward the surface,” said Cottrell. This is because carbon is not associated with oxygen at depth, it exists on its own, like in the mineral diamond. But by the time carbon erupts in lava, it is surrounded by oxygen. In this way, concludes Cottrell, “carbon provides both a mechanism to reduce the iron and also a reasonable explanation for why these reduced lavas are enriched in ways we might expect from melting a carbon-bearing rock.”

Tricky take-off kept pterodactyls grounded

November 24th, 2014

Riffin

A new study, which teamed cutting-edge engineering techniques with paleontology, has found that take-off capacity may have determined body size limits in extinct flying reptiles. The research simulated pterodactyl flight using computer modeling, and will be presented at the upcoming Society of Vertebrate Paleontology meeting in Berlin. Findings suggest that a pterodactyl with a wingspan of 12m or more would simply not be able to get off the ground.

Pterosaurs (commonly known as pterodactyls) were truly giants of the sky. With wingspans of up to 10m, the largest species may have weighed as much as a quarter of a ton. They would have dwarfed the largest known bird at just one third this size. How could such behemoths stay aloft? What prevented them from becoming even bigger?

These questions sparked a novel partnership between Colin Palmer: entrepreneur, mechanical engineer and now doctoral student at Bristol University (UK); and Mike Habib: anatomist and paleontologist at University of Southern California.

“It has been fascinating to apply an engineering approach to understanding biological systems” says Palmer, who has worked on yachts, hovercraft, sailing vessels and windmills before turning to pterosaurs. “Working with Colin has been particularly rewarding” says paleontologist Habib “as we have complimentary skill sets and come at the problem from different backgrounds.”

Pterosaur hunting is illustrated. – Illustration by Mark Witton

The pair used 3D imaging of fossils to create a computer model of a pterosaur with a 6m wingspan. This model was then scaled up to create enlarged models with 9m and 12m wingspans. They were used to estimate the wing strength, flexibility, flying speed and power required for flight in massive pterosaurs.

Results showed that even the largest pterosaur model could sustain flight by using intermittent powered flight to find air currents for gliding. It could also slow down sufficiently to make a safe landing because the pterosaurs wing is formed from a flexible membrane.

Take-off, on the other hand, proved an entirely greater challenge. Unlike modern birds, pterosaur anatomy suggests that they used both their arms and legs to push themselves off the ground during take-off, a maneuver known as the ‘quadrupedal launch’. However, once wingspans approached 12m, the push-off force required to get the model off the ground was too great.

The challenge of propelling a 400kg animal using a quadrupedal launch kept the 12m-wingspan model strictly on terra firma. Palmer concludes “Getting into the air ultimately limited pterosaur size. Even with their unique four legged launch technique, the iron laws of physics eventually caught up with these all time giants of the cretaceous skies.”

Note: This story has been adapted from a news release issued by the Society of Vertebrate Paleontology

Erosion may trigger earthquakes

November 21st, 2014

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Researchers from laboratories at Géosciences Rennes (CNRS/Université de Rennes 1)*, Géosciences Montpellier (CNRS/Université de Montpellier 2) and Institut de Physique du Globe de Paris (CNRS/IPGP/Université Paris Diderot), in collaboration with a scientist in Taiwan, have shown that surface processes, i.e. erosion and sedimentation, may trigger shallow earthquakes (less than five kilometers deep) and favor the rupture of large deep earthquakes up to the surface. Although plate tectonics was generally thought to be the only persistent mechanism able to influence fault activity, it appears that surface processes also increase stresses on active faults, such as those in Taiwan, one of the world’s most seismic regions.

The work is published in Nature Communications on 21 November 2014.

Over the last few decades, many studies have focused on the evolution of mountain range landscapes over geological time (1 to 100 million years). The aim is to better understand the dynamics and interactions between erosion, sedimentation and tectonic deformation processes. Recent work has shown that Earth’s surface can undergo major changes in just a few days, months or years, for instance during extreme events such as typhoons or high magnitude earthquakes. Such events cause many landslides and an increase in sedimentary transport into rivers, as was the case in 2009 when typhoon Morakot struck Taiwan, leading to abrupt erosion of landscapes. Such rapid changes to the shape of Earth’s surface alter the balance of forces at the site of deep active faults.

In Taiwan, where erosion and deformation rates are among the highest in the world, the researchers showed that erosion rates of the order of 0.1 to 20 millimeters per year can cause an increase of the order of 0.1 to 10 bar in stresses on faults located nearby. Such forces are probably enough to trigger shallow earthquakes (less than five kilometers deep) or to favor the rupture of deep earthquakes up to the surface, especially if they are amplified by extreme erosion events caused by typhoons and high magnitude earthquakes. The researchers have thus shown that plate tectonics is not the only persistent mechanism able to influence the activity of seismic faults, and that surface processes such as erosion and sedimentation can increase stresses on active faults sufficiently to cause shallow earthquakes.

Thanks to an analysis of the relationships between surface processes and active deformation of Earth in near real-time, this study provides new perspectives for understanding the mechanisms that trigger earthquakes.

*The Géosciences Rennes laboratory is part of the Observatoire des Sciences de l’Univers de Rennes.

Citation: CNRS. “Erosion may trigger earthquakes.” ScienceDaily. ScienceDaily, 21 November 2014. <www.sciencedaily.com/releases/2014/11/141121082911.htm>

Tectonic plates not rigid, deform horizontally in cooling process

November 19th, 2014

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The puzzle pieces of tectonic plates that make up the outer layer of earth are not rigid and don’t fit together as nicely as we were taught in high school.

Corné Kreemer, associate professor in the College of Science at the University of Nevada, Reno, conducts research on plate tectonics and geodetics. His latest research shows that oceanic tectonic plates deform due to cooling, causing shortening of the plates and mid-plate seismicity.
Credit: Photo by Mike Wolterbeek, University of Nevada, Reno.

A study published in the journal Geology by Corné Kreemer, an associate professor at the University of Nevada, Reno, and his colleague Richard Gordon of Rice University, quantifies deformation of the Pacific plate and challenges the central approximation of the plate tectonic paradigm that plates are rigid.

Using large-scale numerical modeling as well as GPS velocities from the largest GPS data-processing center in the world — the Nevada Geodetic Laboratory at the University of Nevada, Reno — Kreemer and Gordon have showed that cooling of the lithosphere, the outermost layer of Earth, makes some sections of the Pacific plate contract horizontally at faster rates than other sections. This causes the plate to deform.

Gordon’s idea is that the plate cooling, which makes the ocean deeper, also affects horizontal movement and that there is shortening and deformation of the plates due to the cooling. In partnering with Kreemer, the two put their ideas and expertise together to show that the deformation could explain why some parts of the plate tectonic puzzle didn’t fall neatly into place in recent plate motion models, which is based on spreading rates along mid-oceanic ridges. Kreemer and Gordon also showed that there is a positive correlation between where the plate is predicted to deform and where intraplate earthquakes occur. Their work was supported by the National Science Foundation.

Results of the study suggest that plate-scale horizontal thermal contraction is significant, and that it may be partly released seismically. . The pair of researchers are, as the saying goes, rewriting the textbooks.

“This is plate tectonics 2.0, it revolutionizes the concepts of plate rigidity,” Kreemer, who teaches in the University’s College of Science, said. “We have shown that the Pacific plate deforms, that it is pliable. We are refining the plate tectonic theory and have come up with an explanation for mid-plate seismicity.”

The oceanic plates are shortening due to cooling, which causes relative motion inside the plate, Kreemer said. The oceanic crust of the Pacific plate off shore California is moving 2 mm to the south every year relative to the Pacific/Antarctic plate boundary.

“It may not sound like much, but it is significant considering that we can measure crustal motion with GPS within a fraction of a millimeter per year,” he said. “Unfortunately, all existing GPS stations on Pacific islands are in the old part of the plate that is not expected nor shown to deform. New measurements will be needed within the young parts of the plate to confirm this study’s predictions, either on very remote islands or through sensors on the ocean floor.”

This work is complementary to Kreemer’s ongoing effort to quantify the deformation in all of Earth’s plate boundary zones with GPS velocities — data that are for a large part processed in the Nevada Geodetic Laboratory. The main goal of the global modeling is to convert the strain rates to earthquake forecast maps.

“Because we don’t have GPS data in the right places of the Pacific plate, our prediction of how that plate deforms can supplement the strain rates I’ve estimated in parts of the world where we can quantify them with GPS data,” Kreemer said. “Ultimately, we hope to have a good estimate of strain rates everywhere so that the models not only forecast earthquakes for places like Reno and San Francisco, but also for places where you may expect them the least.”

Fossil finds behind mall causing excitement

November 17th, 2014

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A dig site, in New Jersey, is yielding exciting finds: the fossils of animals believed killed around the same time the dinosaurs disappeared. Uncovering the mystery has taken a cast of thousands.

Behind a strip mall in southern New Jersey, paleontologists from Drexel University are traveling 65 million years into the past. This quarry could be the most significant fossil site in decades.

“We know all these animals died at the same time because their bones are still put together,” said Ken Lacovara, the professor leading the dig team.

Lacovara thinks those may be the fossils of thousands of animals that all died around the time a meteor struck and killed off 70 percent of life on earth.

If it turns out to be the case, the only window the world has to animals actually killed in that cataclysm, that wipes out the dinosaurs, and essentially makes the modern world as we know it, is in a pit behind a shopping mall in New Jersey.

Last summer, Lacovara made big news when he announced another discovery — the largest dinosaur in the world.

The dreadnaughtus was bigger than a Boeing 746 and weight 65 tons. Lacovara found it in the wilds of Patagonia in Argentina.

In the New Jersey quarry, the Drexel team has uncovered some amazing fossils over the past 12 years, including a predator the size of a bus, and a 7-foot-long thoracosaurus crocodile that once lived along the coast here.

But this site is special for another reason. For three years now, Lacovara has invited the public to come help dig for a day; 1,300 people have shown up to help.

The people are fascinated, looking almost like they are going to find what’s under the Christmas tree.

“Can you imagine when you’re a kid, when you find your first fossil?” said Lacovara. :That’s a transformational experience, it connects them for the first time in a tangible to the Earth’s ancient past. I think for many of these kids they are never going to forget that moment.

The hope is these kids find more than fossils. Lacovara wants them to discover a love for science.

“I am going to be a paleontologist when I grow up,” said Jordan Lane, who came with her mother and brother. “Because they’re so cool.”

Even with all the help, the team has literally just scratched the surface of what the quarry might reveal.

“If we were to excavate here five days a week we could process an acre in 10 years and this property is 65 acres, so we have about 650 years of work left to do,” said Lacovara. “Geologically, that’s no time at all.”

Which means there will be plenty of work awaiting all these future paleontologists.

Source: CBS News November 16, 2014

How the tortoise’s ribs got embedded in its shell……….

November 15th, 2014

Riffin

Through the careful study of modern and early fossil tortoise, researchers now have a better understanding of how tortoises breathe and the evolutionary processes that helped shape their unique breathing apparatus and tortoise shell. The findings published in a paper, titled: Origin of the unique ventilatory apparatus of turtles, in the scientific journal, Nature Communications, on Friday, 7 November 2014, help determine when and how the unique breathing apparatus of tortoises evolved.

A Computed Tomography rendering of a snapping turtle (Chelydra serpentina) showing the skeleton (white), lungs (blue), and abdominal muscles (red and pink) used to ventilate the lungs. Because turtles have locked their ribs up into the iconic turtle shell, they can no longer use their ribs to breathe as in most other animals and instead have developed a unique abdominal muscle based system.
Credit: Emma R. Schachner

Lead author Dr Tyler Lyson of Wits University’s Evolutionary Studies Institute, the Smithsonian Institution and the Denver Museum of Nature and Science said: “Tortoises have a bizarre body plan and one of the more puzzling aspects to this body plan is the fact that tortoises have locked their ribs up into the iconic tortoise shell. No other animal does this and the likely reason is that ribs play such an important role in breathing in most animals including mammals, birds, crocodilians, and lizards.”

Instead tortoises have developed a unique abdominal muscular sling that wraps around their lungs and organs to help them breathe. When and how this mechanism evolved has been unknown.

“It seemed pretty clear that the tortoise shell and breathing mechanism evolved in tandem, but which happened first? It’s a bit of the chicken or the egg causality dilemma,” Lyson said. By studying the anatomy and thin sections (also known as histology), Lyson and his colleagues have shown that the modern tortoise breathing apparatus was already in place in the earliest fossil tortoise, an animal known as Eunotosaurus africanus.

This animal lived in South Africa 260 million years ago and shares many unique features with modern day tortoises, but lacked a shell. A recognisable tortoise shell does not appear for another 50 million years.

Lyson said Eunotosaurus bridges the morphological gap between the early reptile body plan and the highly modified body plan of living tortoises, making it the Archaeopteryx of turtles.

“Named in 1892, Eunotosaurus is one of the earliest tortoise ancestors and is known from early rocks near Beaufort West,” said Professor Bruce Rubidge, Director of the Evolutionary Studies Institute at Wits University and co-author of the paper.

“There are some 50 specimen of Eunotosaurus. The rocks of the Karoo are remarkable in the diversity of fossils of early tortoises they have produced. The fact that we find Eunotosaurus at the base of the Karoo succession strongly suggest that there are more ancestral forms of tortoises still to be discovered in the Karoo,” Rubidge added.

The study suggests that early in the evolution of the tortoise body plan a gradual increase in body wall rigidity produced a division of function between the ribs and abdominal respiratory muscles. As the ribs broadened and stiffened the torso, they became less effective for breathing which caused the abdominal muscles to become specialised for breathing, which in turn freed up the ribs to eventually — approximately 50 million years later — to become fully integrated into the characteristic tortoise shell.

Lyson and his colleagues now plan to investigate reasons why the ribs of early tortoises starting to broaden in the first place. “Broadened ribs are the first step in the general increase in body wall rigidity of early basal tortoises, which ultimately leads to both the evolution of the tortoise shell and this unique way of breathing. We plan to study this key aspect to get a better understanding why the ribs started to broaden.”

First amphibious ichthyosaur discovered, filling evolutionary gap

November 8th, 2014

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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 fossil 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.

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

Its body also contains thicker bones than previously-described ichthyosaurs. This is in keeping with the idea that most marine reptiles 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.

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.”