Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, 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

‘Lost’ Tectonic Plate Found Beneath California

May 9th, 2013 Riffin

A tectonic plate that disappeared under North America millions of years ago still peeks out in central California and Mexico, new research finds.

The Farallon oceanic plate was once nestled between the Pacific and North American plates, which were converging around 200 million years ago at what would become the San Andreas fault along the Pacific coast. This slow geological movement forced the Farallon plate under North America, a process called subduction.

Much of the Farallon plate got pushed down into the mantle, the gooey molten layer below the Earth’s crust. Off the coast, parts of the plate fragmented, leaving some remnants at the surface, stuck to the Pacific plate.

The Isabella anomaly in California is in line with known remnants of the long-gone Farallon plate.

The Isabella anomaly in California is in line with known remnants of the long-gone Farallon plate.

Now, new research published Monday (March 18) in the journal Proceedings of the National Academy of Sciences, finds that these pieces of Farallon plate are attached to much larger chunks at the surface. In fact, part of the Baja region of Mexico and part of central California near the Sierra Nevada mountains sit upon slabs of Farallon plate.

The finding solves a mystery of California geology. Earth scientists use seismic waves (either recorded from earthquakes or created with dynamic charges or other methods) to map out the region beneath the Earth’s surface. Softer and hotter materials slow seismic waves down. The waves move faster through stiffer, cooler material.

In California, these seismic surveys revealed a large mass of cool, dry material 62 miles to 124 miles (100 to 200 kilometers) below the surface. This strange spot was dubbed the “Isabella anomaly.

Despite many theories, no one had nailed down exactly what caused the Isabella anomaly. Then researchers discovered another anomaly (where the researchers saw a change in seismic wave speed where one wasn’t expected) under the Baja Peninsula, directly east of some of the known remains of the Farallon plate. The proximity led Brown University geophysicists Donald Forsyth and Yun Wang (now at the University of Alaska) to suspect they might be related.

Near the eastern edge of the anomaly, the researchers found volcanic rock deposits called high-magnesium andesites. These are usually linked to the melting of oceanic crust, suggesting that this is the spot where the Farallon plate broke off and subducted, melting into the mantle.

A re-examination of the Isabella anomaly found that it, too, lined up with known Farallon fragments.

“This work has radically changed our understanding of the make-up of the west coast of North America,” study co-author Brian Savage of the University of Rhode Island said in a statement. “It will cause a thorough rethinking of the geological history of North America and undoubtedly many other continental margins.”

Source: Article By Stephanie Pappas, LiveScience Senior Writer | LiveScience.com – Tue, Mar 19, 2013

Acrotholus audeti : a New Species of Dinosaur

May 8th, 2013 Riffin

Scientists have named a new species of bone-headed dinosaur (pachycephalosaur) from Alberta, Canada. Acrotholus audeti (Ack-RHO-tho-LUS) was identified from both recently discovered and historically collected fossils. Approximately six feet long and weighing about 40 kilograms in life, the newly identified plant-eating dinosaur represents the oldest bone-headed dinosaur in North America, and possibly the world.

Dr. Michael Ryan, curator of vertebrate paleontology at The Cleveland Museum of Natural History, co-authored research describing the new species, which was published May 7, 2013 in the journal Nature Communications.

Life reconstruction of the new pachycephalosaurid dinosaur Acrotholus audeti. Credit: Julius Csotonyi

Life reconstruction of the new pachycephalosaurid dinosaur Acrotholus audeti. Credit: Julius Csotonyi

Acrotholus means “high dome,” referring to its dome-shaped skull, which is composed of solid bone over 10 centimeters (two inches) thick. The name Acrotholus audeti also honors Alberta rancher Roy Audet, on whose land the best specimen was discovered in 2008. Acrotholus walked on two legs and had a greatly thickened, domed skull above its eyes, which was used for display to other members of its species, and may have also been used in head-butting contests. Acrotholus lived about 85 million years ago.

The new dinosaur discovery is based on two skull ‘caps’ from the Milk River Formation of southern Alberta. One of these was collected by the Royal Ontario Museum (ROM) more than 50 years ago. However, a better specimen was found in 2008 by University of Toronto graduate student Caleb Brown during a field expedition organized by Dr. David Evans of the Royal Ontario Museum and University of Toronto, and Ryan.

“Acrotholus provides a wealth of new information on the evolution of bone-headed dinosaurs. Although it is one of the earliest known members this group, its thickened skull dome is surprisingly well-developed for its geological age,” said lead author Evans, ROM curator, vertebrate palaeontology. “More importantly, the unique fossil record of these animals suggests that we are only beginning to understand the diversity of small-bodied plant-eating dinosaurs.”

Small mammals and reptiles can be very diverse and abundant in modern ecosystems, but small dinosaurs (less than 100 kg) are considerably less common than large ones in the fossil record. Whether this pattern is a true reflection of dinosaur communities, or is related to the greater potential for small bones to be destroyed by carnivores and natural decay, has been debated. The massively constructed skull domes of pachycephalosaurs are resistant to destruction, and are much more common than their relatively delicate skeletons — which resemble those of other small plant-eating dinosaurs. Therefore, the researchers suggest that the pachycephalosaur fossil record can provide valuable insights into the diversity of small, plant-eating dinosaurs as a whole.

“We can predict that many new small dinosaur species like Acrotholus are waiting to be discovered by researchers willing to sort through the many small bones that they pick up in the field,” said co-author Ryan of The Cleveland Museum of Natural History. “This fully domed and mature individual suggests that there is an undiscovered, hidden diversity of small-bodied dinosaurs. So when we look back, we need to reimagine the paleoenvironment. There is an evolutionary history that we just don’t know because the fossil record is incomplete. This discovery also highlights the importance of landowners, like Roy Audet, who grant access to their land and allow scientifically important finds to be made.”

This dinosaur is the latest in a series of new finds being made by Evans and Ryan as part of their Southern Alberta Dinosaur Project, which aims to fill in gaps in of the record of Late Cretaceous dinosaurs and study their evolution. This project focuses on the palaeontology of some of the oldest dinosaur-bearing rocks in Alberta, which have been studied less intensely than those of the famous badlands of Dinosaur Provincial Park and Drumheller.

Acrotholus was identified by a team comprising of palaeontologists Evans, of the Royal Ontario Museum; and Ryan, of The Cleveland Museum of Natural History; as well as Ryan Schott, Caleb Brown, and Derek Larson, all graduate students at the University of Toronto who studied under Evans.

Ancient Genetic Data from Black Sea

May 7th, 2013 Riffin

When Woods Hole Oceanographic Institution (WHOI) marine paleoecologist Marco Coolen was mining through vast amounts of genetic data from the Black Sea sediment record, he was amazed about the variety of past plankton species that left behind their genetic makeup (i.e., the plankton paleome).

The semi-isolated Black Sea is highly sensitive to climate driven environmental changes, and the underlying sediments represent high-resolution archives of past continental climate and concurrent hydrologic changes in the basin. The brackish Black Sea is currently receiving salty Mediterranean waters via the narrow Strait of Bosphorus as well as freshwater from rivers and via precipitation.

The breach of the Bosporus sill connected the Black Sea to the Sea of Marmara and the world ocean. As glaciers melted and global sea levels began to rise, the Black Sea also rose, bringing it to its present day level. (Credit: Jack Cook, Woods Hole Oceanographic Institution)

The breach of the Bosporus sill connected the Black Sea to the Sea of Marmara and the world ocean. As glaciers melted and global sea levels began to rise, the Black Sea also rose, bringing it to its present day level. (Credit: Jack Cook, Woods Hole Oceanographic Institution)

 

“However, during glacial sea level lowstands, the marine connection was hindered, and the Black Sea functioned as a giant lake,” says WHOI geologist Liviu Giosan.

 

He added that “the dynamics of the environmental changes from the Late Glacial into the Holocene (last 10,000 years) remain a matter of debate, and information on how these changes affected the plankton ecology of the Black Sea is sparse.”

 

Using a combination of advanced ancient DNA techniques and tools to reconstruct the past climate, Coolen, Giosan, and their colleagues have determined how communities of plankton have responded to changes in climate and the influence of humans over the last 11,400 years. Their results will be published in the Proceedings of the National Academy of Sciences, USA (PNAS), and will be available online on May 6.

 

Researchers traditionally reconstruct the make up of plankton by using a microscope to count the fossil skeletons found in sediment cores. But, this method is limited because most plankton leave no fossils, so instead Coolen looked for sedimentary genomic remains of the past inhabitants of the Black Sea water column.

 

“DNA offers the best opportunity to learn the past ecology of the Black Sea,” says Coolen. “For example, calcareous and organic-walled dinocysts are frequently used to reconstruct past environmental conditions, but 90 percent of the dinoflagellate species do not produce such diagnostic resting stages, yet their DNA remains in the fossil record.”

 

However, ancient DNA signatures in marine sediments have thus far been used for targeted reconstruction of specific plankton groups and those studies were based on very small clone libraries. Instead, the researchers used a high throughput next generation DNA sequencing approach called pyrosequencing to look for the overall plankton changes in the Back Sea from the deglaciation to recent times.

 

In addition, the researchers reconstructed past changes in salinity and temperature as the possible causes for plankton community shifts in the Black Sea.

 

To reconstruct the salinity, the WHOI team analyzed sediments containing highly resistant organic compounds called alkenones, which are uniquely produced by Emiliania huxleyi — the same photosynthetic organism oceanographers study to determine past sea surface temperatures. By examining the ratio of two hydrogen isotopes in the alkenones, they were able to map the salinity trend in the Black Sea over the last 6,500 years.

 

“One of the isotopes, deuterium, is not very common in nature,” explains Coolen, “And it doesn’t evaporate as easily as other isotopes. Higher ratios of deuterium are indicative of higher salinity.”

 

The WHOI team was funded through the National Science Foundation and they collaborated with Chris Quince and his postdoc Keith Harris from the Computational Microbial Genomics Group at the University of Glasgow, and with micropaloentologist Mariana Filipova-Marinova from the Natural History Museum in Varna, Bulgaria.

 

Their study revealed that 150 of 2,710 identified plankton showed a statistically significantly response to four environmental stages since the deglacial. Freshwater green algae were the best indicator species for lake conditions more than 9,000 years ago although the co-presence of previously unidentified marine plankton species indicated that the Black Sea might have been influenced to some extent by the Mediterranean Sea over at least the past 9,600 years. Dinoflagellates, cercozoa, eustigmatophytes, and haptophyte algae responded most dramatically to the gradual increase in salinity after the latest marine reconnection and during the warm and moist mid-Holocene climatic optimum. Salinity increased rapidly with the onset of the dry Subboreal climate stage after ca. 5200 years ago leading to an increase in marine fungi and the first occurrence of marine copepods. A gradual succession of phytoplankton such as dinoflagellates, diatoms, and golden algae occurred during refreshening of the Black Sea with the onset of the cool and wet Subatlantic climate around 2500 years ago. The most drastic changes in plankton occurred over the last century associated with recent human disturbances in the region.

 

The new findings show how sensitive marine ecosystems are to climate and human impact. The high throughput sequencing of ancient DNA signatures allows us to reconstruct a large part of ancient oceanic life including organisms that are not preserved as fossils.

 

Coolen added that ancient plankton DNA was even preserved in the oldest analyzed Black Sea lake sediments when the entire water column was most likely well mixed and oxygenated. This means that ancient plankton DNA might be widely preserved in sediments and can likely be used to reconstruct past life in the majority of oceanic and lake environments.

Long Lost Cousin of T. Rex Identified by Scientists

May 6th, 2013 Riffin

Scientists have identified a new species of gigantic theropod dinosaur, a close relative of T. rex, from fossil skull and jaw bones discovered in China.

According to findings published online on April 1, 2011 in the scientific journal Cretaceous Research, the newly named dinosaur species Zhuchengtyrannus magnus probably measured about 11 metres long, stood about 4 metres tall, and weighed close to 6 tonnes.

The newly named dinosaur species Zhuchengtyrannus magnus probably measured about 11 metres long, stood about 4 meters tall, and weighed close to 6 tons. Comparable in size and scale to the legendary T. rex, this new dinosaur is one of the largest theropod (carnivorous) dinosaurs ever identified by scientists. (Credit: Copyright Robert Nicholls)

The newly named dinosaur species Zhuchengtyrannus magnus probably measured about 11 metres long, stood about 4 meters tall, and weighed close to 6 tons. Comparable in size and scale to the legendary T. rex, this new dinosaur is one of the largest theropod (carnivorous) dinosaurs ever identified by scientists. (Credit: Copyright Robert Nicholls)

Comparable in size and scale to the legendary T. rex, this new dinosaur is one of the largest theropod (carnivorous) dinosaurs ever identified by scientists.

Alongside T. rex and the Asian Tarbosaurus, Zhuchengtyrannus magnus is one of a specialised group of gigantic theropods called tyrannosaurines. The tyrannosaurines existed in North America and eastern Asia during the Late Cretaceous Period, which lasted from about 99 to 65 million years ago.

“Zhuchengtyrannus can be distinguished from other tyrannosaurines by a combination of unique features in the skull not seen in any other theropod,” explains Dr David Hone from the UCD School of Biology and Environmental Science at University College Dublin, Ireland, the lead author of the scientific paper.

“With only some skull and jaw bones to work with, it is difficult to precisely gauge the overall size of this animal. But the bones we have are just a few centimetres smaller than the equivalent ones in the largest T. rex specimen. So there is no doubt that Zhuchengtyrannus was a huge tyrannosaurine.”

“We named the new genus Zhuchengtyrannus magnus — which means the ‘Tyrant from Zhucheng’ — because the bones were found in the city of Zhucheng, in eastern China’s Shandong Province,” says Dr Hone.

A key member of the international team of scientists involved in the study is Professor Xu Xing of the Beijing Institute of Vertebrate Paleontology and Paleoanthropology in China. Professor Xu has named more than 30 dinosaurs, making him the world leader in describing new dinosaur species.

The tyrannosaurines, the group including T. rex and its closest relatives, were huge carnivores characterised by small arms, two-fingered hands, and large powerful jaws that could have delivered a powerful bone-crushing bite. They were likely both predators and scavengers.

Together with nearby sites, the quarry in Shandong Province, eastern China where the remains of this huge carnivore were found contains one of the largest concentrations of dinosaur bones in the world. Most of the specimens recovered from the quarry belong to a gigantic species of hadrosaur, or duck-billed dinosaur. Research suggests that the area contains so many dinosaur fossils because it was a large flood plain where many dinosaur bodies were washed together during floods and fossilised.

Killer Entrance Suspected in Mystery of Unusually Large Group of Carnivores in Ancient Cave

May 5th, 2013 Riffin

An assortment of saber-toothed cats, hyenas, an extinct ‘bear-dog’, ancestors of the red panda and several other carnivores died under unusual circumstances in a Spanish cave near Madrid approximately 9-10 million years ago. It now appears that the animals may have entered the cave intentionally and been trapped there, according to research published May 1 in the open access journal PLOS ONE by Soledad Domingo from the University of Michigan and colleagues from other institutions.

This is the interior of Batallones-1 trap showing two individuals of the sabertoothed cat Machairodus aphanistus feeding from the carcass of a rhinoceros. (Credit: Mauricio Antón)

This is the interior of Batallones-1 trap showing two individuals of the sabertoothed cat Machairodus aphanistus feeding from the carcass of a rhinoceros. (Credit: Mauricio Antón)

Different reasons have previously been offered to explain the unusually large concentration of healthy adult carnivores in this cave, including mass mortality, accidental falls into the cave, or simply that the animals died in other locations and were washed up into the cave. However, none of these could explain the absence of herbivores (nearly 98% of the fossils are of carnivores) or the large numbers of apparently healthy adults.

In the present study, authors examined the geological conditions under which the cave was formed, the age of individuals in the cave and the time frame over which they likely entered this pit. Tracking clues like the demography of the individuals recovered, the orientation of the remains and scarcity of fractured bones or trampling marks, among others, the researchers conclude that the animals most likely actively entered the cavity in search of food or water over a protracted period of time and were subsequently unable to make their way out, ultimately dying in the cave.

They suggest that the scarcity of herbivore remains may indicate that the cavity was clearly visible and thus avoided by these animals. Fossil bones in this site exhibit a very good preservation state as a consequence of their deposition in the restricted and protective environment of the chamber.

A new Species dinosaur fossil discovered in China

May 4th, 2013 Riffin

Fossil remains found by a George Washington University biologist in northwestern China have been identified as a new species of small theropod, or meat-eating, dinosaur.

The discovery was made by James Clark, the Ronald B. Weintraub Professor of Biology, in the Department of Biological Sciences of GW’s Columbian College of Arts and Sciences. Dr. Clark, along with his then doctoral student Jonah Choiniere and a team of international researchers, found the dinosaur specimen in a remote region of Xinjiang in China in 2006.

James Clark, George Washington University This baby dinosaur, found in China's Shishugou Formation, was identified as a new species, Aorun zhaoi.

James Clark, George Washington University
This baby dinosaur, found in China’s Shishugou Formation, was identified as a new species, Aorun zhaoi.

In a research paper published in the Journal of Systematic Palaeontology, Drs. Clark and Choiniere explain recovering the skull, mandible and partial skeleton of the dinosaur. The new theropod was an estimated 1 meter or just over 3 feet long and probably weighed about 3 pounds.

“All that was exposed on the surface was a bit of the leg,” said Dr. Clark. “We were pleasantly surprised to find a skull buried in the rock too.”

The dinosaur is named Aorun zhaoi, after the Dragon King in the Chinese epic tale Journey to the West. It wasn’t necessarily a small dinosaur species, though, because Aorun was still a youngster when it became a fossil.

“We were able to look at microscopic details of Aorun’s bones and they showed that the animal was less than a year old when it died on the banks of a stream,” said Dr. Choiniere.

Dr. Choiniere, now a senior researcher at the Evolutionary Studies Institute at the University of the Witwatersrand in Johannesburg, South Africa, was a doctoral student in Biological Studies at GW when the discovery was made. He was also a Kalbfleisch Fellow and Gerstner Scholar at the American Museum of Natural History.

Aorun lived more than 161 million years ago, in the earliest part of the Late Jurassic Period. Its small, numerous teeth suggest that it would have eaten prey like lizards and small relatives of today’s mammals and crocodilians.

This is the fifth new theropod discovered at the Wucaiwan locality by the team, co-led by Dr. Clark and Dr. Xu Xing of the Chinese Academy of Sciences.

This research was funded by the National Science Foundation Division of Earth Sciences and the Chinese National Natural Science Foundation.

WFS Profile:José Fernando Bonaparte

May 3rd, 2013 Riffin

José Fernando Bonaparte, Ph.D. (born June 14, 1928), is an Argentine paleontologist who discovered a plethora of South American dinosaurs and mentored a new generation of Argentine paleontologists like Rodolfo Coria. According to University of Pennsylvania paleontologist Peter Dodson, “almost singlehandedly he’s responsible for Argentina becoming the sixth country in the world in kinds of dinosaurs”

Paleontologist Jose Bonaparte

Paleontologist Jose Bonaparte

Bonaparte is the son of an Italian sailor. He was born in Rosario, Argentina, and grew up in Mercedes, Buenos Aires. Despite a lack of formal training in paleontology, he started collecting fossils at an early age, and created a museum in his home town. He later became the curator of the National University of Tucumán, were he was named Doctor Honoris causa in 1974, and then in the late 1970s became a senior scientist at the National Museum of Natural Sciences in Buenos Aires.

Paleontologist Jose Bonaparte

Paleontologist Jose Bonaparte

 

Discoveries

Southern diversity

The supercontinent of Pangea split into Laurasia in the north and Gondwana in the south during the Jurassic. During the Cretaceous, South America pulled away from the rest of Gondwana. The division caused a divergence between northern biota and the southern biota, and the southern animals appear strange to those used to the more northerly fauna. Bonaparte’s finds illustrate this divergence, and caused paleontologist Robert Bakker to dub him the “Master of the Mesozoic“.

In South America, the titanosaurs developed armor and flourished, while the sauropods of the northern continent were dying out and being replaced by vast herds of hadrosaurs; the carnivorous theropods were represented by abelisaurs and strange-looking dinosaurs like the horned, short-armed, and stub-nosed Carnotaurus. There are indications that a land bridge reunited North and South America during the Late Cretaceous because titanosaurs have been discovered as far north as Utah and duck-bills as far south as Patagonia.

List of dinosaurs named

 

Source: Wikipedia.

Weird Dino Ancestors Boomed After Mass Extinction

May 2nd, 2013 Riffin

Dinosaurs — or at least their ancestors — may have gotten an earlier start than once believed.

Bizarre four-legged creatures that resembled demonic dogs and predated dinosaurs branched out shortly after an extinction that wiped out most of life on land, according to a new study. Some of these creatures were the direct ancestors of dinosaurs, and their flourishing toehold in what is now Africa and Antarctica appears to have benefited from the clean slate of the mass extinction.

The pig-size Dicynodon was part of a large, dominant group of plant eaters found across the southern hemisphere until the mass extinction event weakened their numbers so that newly emerging herbivores could compete. New research published April

“We get the hint that the dinosaur radiation, which we don’t really see in the fossil record until about 20 million years later, is really starting to take off in this region,” said Christian Sidor, a biologist at the University of Washington and a research associate at the Field Museum of Natural History in Chicago.

Vanished life

About 252 million years ago, 90 percent of marine life and about 70 percent of land animals vanished in what’s known as the Permian-Triassic extinction event. No one knows why the mass extinction happened; theories include meteorite impacts, an uptick in volcanic activity or the release of carbon dioxide and methane, which would have caused major climate upheaval.

Among the weird creatures roaming the Earth at the time was the Dicynodon, a pig-size, four-legged animal that had the lizardlike look of the demonic dogs in 1984’s “Ghostbusters.” Just replace the canine teeth with beaks, and nix the glowing red eyes.

“They have short tails, two big tusks that are ever-growing like an elephant[’s], and they have a beak like a turtle,” Sidor told LiveScience.

Dicynodon and its contemporaries lived on Pangaea, a single landmass made of all of today’s continents mashed together into one. The fossil record around the Permian extinction is spotty, with most paleontological research coming from a few fossil sites in Russia and in South Africa. Sidor and his colleagues wanted to broaden that range to better understand the post-extinction ecosystem across southern Pangaea, or what would today be Africa, South America, India, Australia and Antarctica.

Emerging ecosystems

To do so, the researchers analyzed fossils — some newly found and others in museum collections — from Tanzania, Zambia, Malawi and Antarctica, as well as the Karoo Basin in South Africa, where the Permian extinction record is long known. The project involved years of fieldwork, including at a base camp situated halfway between the McMurdo Station, a research base in Antarctica; and the South Pole, where rocks are periodically covered and uncovered by snow and ice.

“It’s a huge logistical thing, as you might imagine,” Sidor said.

The fossils revealed that the landscape 5 million years before the extinction, animal diversity was similar across all five sites, dominated particularly by the herbivorous Dicynodon. At the next fossil snapshot, 10 million years post-extinction, the five regions had diversified significantly.

After the Permian extinction, Dicynodon lost its perch as the dominant herbivore. Though it did not go extinct until about 200 million years ago, Dicynodon never regained its prominence. ,

“After the extinction, things change dramatically,” Sidor said. “The animals that are common in the Karoo are not the ones that are common in Tanzania.”

In particular, Sidor said, the post-extinction landscape hosted many archosaurs, a group that includes crocodiles, birds, flying reptiles called pterosaurs and non-avian dinosaurs. An animal that may be the earliest known dinosaur, or at least the archosaur most closely related to dinosaurs — Nyasasaurus parringtoni—comes from Tanzania and lived about 245 million to 240 million years ago.

“There are a whole bunch of different archosaurs,” Sidor said. “There were plant-eaters, large carnivores, armored forms — so they were really taking off into a variety of different body forms. It’s not just the origin of dinosaurs we’re tracing backwards, but seemingly a completely different ecosystem in Tanzania than what you see in South Africa.”

It’s not clear how two similar ecosystems could emerge to be so different after a mass extinction, Sidor said, but it’s not an uncommon occurrence. He likened the change to politics: It’s hard to dislodge an incumbent politician, but once you do, anyone could step in to fill the gap.

Some scientists believe that the Earth is now undergoing another mass extinction, due to human activity. If this is the case, Sidor said, the Permian extinction is a cautionary tale.

“Mass extinctions have unpredictable consequences,” he said. “You couldn’t tell, based on what was existing before the extinction, what’s going to do well afterwards.”

The researchers report their findings this week in the journal Proceedings of the National Academy of Sciences.

Source: By Stephanie Pappas, LiveScience Senior Writer | LiveScience.com – Mon, Apr 29, 2013

First Land Animals Kept Fishlike Jaws for Millions of Years

May 1st, 2013 Riffin

Scientists studying how early land vertebrates evolved from fishes long thought that the animals developed legs for moving around on land well before their feeding systems and dietary habits changed enough to let them eat a land-based diet, but strong evidence was lacking. Now, for the first time fossil jaw measurements by Philip Anderson at the University of Massachusetts Amherst and others have tested and statistically confirmed this lag.

“This pattern had been hypothesized previously, but not really tested. Now we’ve done that,” Anderson says. He and his team found that the mechanical properties of tetrapod jaws did not show significant adaptations to land-based feeding until some 40 to 80 million years after the four-legged creatures initially came out of the water. Until then, tetrapod jaws were still very fish-like, even though their owners had weight-bearing limbs and the ability to walk on land. Anderson says this finding suggests tetrapods may have shown a limited variety of feeding strategies in the early phases of their evolution on land.

“What it took to really initiate evolutionary changes in the jaw system was for these animals to start eating plants,” he says. For the study, published in an early online edition of the journal Integrative and Comparative Biology, Anderson and researchers Matt Friedman of the University of Oxford and Marcello Ruta of the University of Lincoln, U.K., examined images of 89 fossils of early tetrapods and their fish-like forebears. The fossils ranged in age from about 400 to 300 million years old. Anderson and his team were interested in how the jaws of these fossilized animals differed through time.

A juvenile Orobates pabsti, a reptile-like four-legged amphibian. Philip Anderson of UMass Amherst and colleagues examined images of 89 fossils of early tetrapods and their fish-like forebears ranging in age from about 400 to 300 million years old. The pictured specimen is from the Museum Der Natur in Gotha, Germany. (Credit: Thomas Martens, Stiftung Schloss Friedenstein Gotha, Germany)

A juvenile Orobates pabsti, a reptile-like four-legged amphibian. Philip Anderson of UMass Amherst and colleagues examined images of 89 fossils of early tetrapods and their fish-like forebears ranging in age from about 400 to 300 million years old. The pictured specimen is from the Museum Der Natur in Gotha, Germany. (Credit: Thomas Martens, Stiftung Schloss Friedenstein Gotha, Germany)

They used 10 biomechanical metrics to describe jaw differences. One of these, called mechanical advantage, measured how much force an animal can transfer to its bite. Anderson points out that while fossils can’t tell you what an animal actually ate, scientists can infer potential feeding behavior from fossilized evidence of biomechanical tools like jaws. The researchers compared jaw features from the fossil record and calculated the rates at which jaws evolved.

“The basic result was that it took a while for these animals to adapt their jaws for a land-based diet,” Anderson says. “They stayed essentially fish-like for a long time.”

It turns out that just moving into a new environment is not always enough to trigger functional adaptations. In their paper, the authors say the results may be explained by an earlier hypothesis: A shift from gilled to lung breathing in later tetrapod groups was necessary before they could devote their jaw structure to eating plants.

Anderson says the statistical methods they developed for this work could be used in future studies of more subtle biomechanical patterns in fossil animals that may not be initially clear.

First Snapshot of Organisms Eating Each Other: Feast Clue to Smell of Ancient Earth

April 30th, 2013 Riffin

Tiny 1,900 million-year-old fossils from rocks around Lake Superior, Canada, give the first ever snapshot of organisms eating each other and suggest what the ancient Earth would have smelled like.

The fossils, preserved in Gunflint chert, capture ancient microbes in the act of feasting on a cyanobacterium-like fossil called Gunflintia — with the perforated sheaths of Gunflintia being the discarded leftovers of this early meal.

A team, led by Dr David Wacey of the University of Western Australia and Bergen University, Norway, and Professor Martin Brasier of Oxford University, reports in this week’s Proceedings of the National Academy of Sciences the fossil evidence for how this type of feeding on organic matter — called ‘heterotrophy’ — was taking place. They also show that the ancient microbes appeared to prefer to snack on Gunflintia as a ‘tasty morsel’ in preference to another bacterium (Huroniospora).

A 3D reconstruction of tubular Gunflintia fossils being eaten by heterotrophic bacteria (orange spheres and rod-shapes) gives the first ever snapshot of organisms eating each other, Oxford University and University of Western Australia scientists report. (Credit: David Wacey)

A 3D reconstruction of tubular Gunflintia fossils being eaten by heterotrophic bacteria (orange spheres and rod-shapes) gives the first ever snapshot of organisms eating each other, Oxford University and University of Western Australia scientists report. (Credit: David Wacey)

‘What we call ‘heterotrophy’ is the same thing we do after dinner as the bacteria in our gut break down organic matter,’ said Professor Martin Brasier of Oxford University’s Department of Earth Sciences, an author of the paper. ‘Whilst there is chemical evidence suggesting that this mode of feeding dates back 3,500 million years, in this study for the first time we identify how it was happening and ‘who was eating who’. In fact we’ve all experienced modern bacteria feeding in this way as that’s where that ‘rotten egg’ whiff of hydrogen sulfide comes from in a blocked drain. So, rather surprisingly, we can say that life on earth 1,900 million years ago would have smelled a lot like rotten eggs.’

The team analysed the microscopic fossils, ranging from about 3-15 microns in diameter, using a battery of new techniques and found that one species — a tubular form thought to be the outer sheath of Gunflintia — was more perforated after death than other kinds, consistent with them having been eaten by bacteria.

In some places many of the tiny fossils had been partially or entirely replaced with iron sulfide (‘fool’s gold’) a waste product of heterotrophic sulfate-reducing bacteria that is also a highly visible marker. The team also found that these Gunflintia fossils carried clusters of even smaller (c.1 micron) spherical and rod-shaped bacteria that were seemingly in the process of consuming their hosts.

Dr Wacey said that: ‘recent geochemical analyses have shown that the sulfur-based activities of bacteria can likely be traced back to 3,500 million years or so — a finding reported by our group in Nature Geoscience in 2011. Whilst the Gunflint fossils are only about half as old, they confirm that such bacteria were indeed flourishing by 1,900 million years ago. And that they were also highly particular about what they chose to eat.’

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