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New, improved zebrafish cloning method may further human health research

September 1, 2009 By admin Leave a Comment

London, August 31 (ANI): In what may eventually prove very useful in human health research, scientists at Michigan State University have come up with a more efficient method to clone zebra fish.

What makes this work an important achievement is the fact that zebra fish, which have served as an excellent model for understanding normal development and birth defects for more than 20 years, are quickly becoming the animal of choice for many researchers.

“After the mouse, it is the most commonly used vertebrate in genetic studies. It is used in cancer research and cardiovascular research because they have many of the same genes we have,” Nature magazine quoted Jose Cibelli, an MSU professor of Animal Science, as saying.

While previous methods of cloning zebra fish have had very low success rates, the MSU researchers say that their novel method can increase the number of cloned fish that can be obtained from an adult fin cell or an embryonic tail clip increased by 2 percent to 13 percent, respectively.

What makes zebra fish so useful in research is their eggs are transparent and the fish’s development is easy to follow.

Improving on the techniques of zebra fish cloning also is important because currently only the mouse remains the best model for gene targeting.

“So far the mouse is the only one from which you can delete genes in a reliable fashion. What researchers do is mutate a gene, abolish its function completely, and then study the consequences,” Cibelli said.

A research article describing the novel technique has been published in the journal Nature Methods. (ANI)

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New species of lungless salamander found in Appalachian foothills of the US

July 10, 2009 By admin Leave a Comment

London, July 9 (ANI): A striking new species of lungless salamander has been found living in a small stream in the Appalachian foothills of the US.

According to a report by BBC News, the salamander, scientifically known as ‘Urspelerpes brucei’, is so distinct that it’s been classified within its own genus, a taxonomic grouping that usually includes a host of related species.

The creature breathes through its skin, and unusually for its kind, males and females have different colouration.

Such a distinct amphibian has not been found in the US for half a century.

The researchers who discovered the creature have dubbed it the ‘patch-nosed’ salamander after the yellow patch on the animal’s snout.

The tiny animal averages just 25 to 26mm long.

The researchers found so few of the animals that either it is highly secretive, or more likely it survives in such small, isolated numbers that it is already at risk of extinction.

“This animal is really a spectacular find,” said Biologist Carlos Camp of Piedmont College in Demorest, Georgia, who led the team which described the new species.

“It is the first genus of amphibian, indeed of any four-footed vertebrate, discovered in the US in nearly 50 years,” he added.

The Appalachian Highlands of the southeastern US is a hot spot for lungless salamander diversity, with species occupying a variety of moist or wet environments including living in streams, underground, among the leaf litter of the forest floor, up cliffs and in trees.

“The salamander fauna of the US, particularly of the southern Appalachians, has been intensively studied for well over a century, so the discovery of such a distinct form was completely unsuspected,” said Carlos.

The amphibian also looks strikingly different to other species.

For a start, it has the smallest body size of any salamander in the US.

It is also the only lungless salamander in the US whose males have a different colour and pattern than females, a trait more characteristic of birds.

Males have a pair of distinct dark stripes running down the sides of the body and a yellow back. Females lack stripes and are more muted in colour.

Males also have 15 vertebrae, one less than females. Yet while most species of lungless salamander have male and females of differing sizes, those of Urspelerpes brucei are close to being equal in size.

Uniquely for such a small lungless salamander, Urspelerpes brucei has five toes, whereas most other small species have reduced that number to four. (ANI)

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Gargantuan dinos the ‘couch potatoes’ of prehistoric world

July 7, 2009 By admin Leave a Comment

London, July 7 (ANI): A new research has determined that due to their huge sizes, dinosaurs were the ‘couch potatoes’ of the prehistoric world.

According to a report in the Telegraph, the research was done by Dr McNab from the University of Florida.

Having easy access to food, coupled with their sedentary lifestyle when not hunting, helped the creatures grow into the biggest beasts to have ever walked the earth, according to Dr McNab.

Paleontologists have argued that dinosaurs’ size was in some way due to the way they regulated the temperature of their blood.

Dr McNab believes that the availability of food resources was more important, however.

Using a model based on a vertebrate’s energy expenditure, mass and eating habits, Dr McNab explained the body size of existing and extinct mammals, including baleen whales, an ancient rhinoceros and modern elephants.

He used the example of the larger mass found in some marine mammals which reflect greater resources in their environment.

While Dr McNab said that thermal biology differences are easily seen in small organisms, he suggested dinosaurs were neither cold nor warm blooded but maintained an intermediate temperature between mammals and reptiles, thanks to their size.

Some dinosaurs ate lizards, turtles or eggs, while others hunted other dinosaurs. The majority ate plants however.

Many of these plants, which can be seen in fossils, had edible leaves, including evergreen conifers such as pine trees, redwoods and their relatives, ferns, mosses and in the latter stages of the dinosaur age, flowering fruit plants.

According to Dr McNab, “Like couch potatoes sitting within easy reach of high calorie foods, the gargantuan size of dinosaurs most likely stems from the abundance of resources available, coupled with low energy expenditures.”

“Some dinosaurs reached masses that were at least eight times those of the largest, ecologically equivalent terrestrial mammals,” he said.

“The factors most responsible for setting the maximal body size of vertebrates are resource quality and quantity, as modified by the mobility of the consumer, and the vertebrate’s rate of energy expenditure,” he added. (ANI)

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Primates evolved larger brains to hop between trees

July 1, 2009 By admin Leave a Comment

Washington, July 1 (ANI): A new study, in which scientists scanned a 54-million-year-old skull roughly the size of a walnut, has suggested that primates such as lemurs, monkeys, apes, and humans might have evolved larger brains as a result of the need to move quickly from tree to tree.

According to a report in National Geographic News, the 1.5-inch-long (4-centimeter-long) skull belongs to the long-gone Ignacius graybullianus, described as a cousin of our earliest ancestors, which arose less than ten million years after the dinosaurs vanished.

Discovered in Wyoming roughly 25 years ago, the fossil “is the most complete early primate skull known,” said study co-author Jonathan Bloch, a vertebrate paleontologist at the University of Florida.

Due to its completeness and age, the skull gives us the clearest idea yet what early primates were like, according to the researchers.

After taking more than 1,200 detailed X-ray images of the skull, researchers combined them to help create a 3-D model of Ignacius’ brain.

The model showed a brain just one-half to two-thirds the size of the smallest modern primate brain, the study said.

It seems that such a small brain was enough for tree dwelling and fruit seeking.

Ignacius’ teeth, for example, suggest it had a fruit diet, while the animal’s claws and flexible joints hint at tree dwelling.

The finding therefore reopens the question of what triggered the evolution of large brains in later primate species, if not branch living or fruit eating?

One activity Ignacius seems unsuited for is jumping from tree to tree, as opposed to simply climbing branches.

In primates, this type of leaping generally requires long hind limbs, large inner-ear organs linked to balance-and strong visual processing.

Instead of a robust center of vision, Ignacius’ brain had large lobes dedicated to smelling, the model suggests.

The prehistoric primate “was mostly a nose-first animal that relied on smell instead of sight, unlike modern primates, which have far more developed visual processing areas,” explained lead study author Mary Silcox, a vertebrate paleontologist at the University of Winnipeg.

“For primates, stepping up vision would have been key for leaping safely,” she surmised.

But, to do that, the brain had to be larger, which eventually happened as a result of evolution. (ANI)

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Duckbilled dino had skin like birds and crocodiles

July 1, 2009 By admin Leave a Comment

Washington, July 1 (ANI): A new study of a remarkably preserved fossil of a duckbilled dinosaur has revealed that the prehistoric reptile had skin like that of birds and crocodiles.

According to a report in National Geographic News, advanced imaging and chemical techniques revealed that the 66-million-year-old “mummified” duckbilled dinosaur had two layers of skin, as do modern vertebrates, including humans.

Such a discovery was possible because the dinosaur’s skin fossilized before bacteria had a chance to eat up the tissue.

It is “absolutely amazing to be able to identify organic molecules from soft tissue that belonged to a beast that died over 66 million years ago,” said excavation leader Phillip Manning, a paleontologist at Britain’s University of Manchester. “It’s certainly in my top ten all-time (most significant) fossils,” he added.

Tyler Lyson, a teenager at the time, discovered Dakota, as the fossil was later dubbed, in 1999 on his family’s North Dakota property.

No one knows how the hippo-size animal died. But, scientists do know that the body was probably buried rapidly.

The resulting low-oxygen environment and the apparent lack of disturbance to the site made Dakota a “world-class dinosaur” fossil, according to the new study.

With electron microscopes and x-rays, Manning discovered that Dakota had cell-like structures indicative of two-ply skin: a thin surface layer plus an underlying layer of dense connective tissues.

That’s just like skin of modern birds and reptiles, which scientists believe are closely related to duckbilled dinosaurs.

Protein-recovery techniques used on the skin and a claw detected amino acids, the building blocks of proteins.

Proteins themselves, complex molecules that degrade easily over time, were not found, however.

But, Manning did identify molecules that would have broken down proteins in Dakota’s body.

That’s like finding fragments of a broken vase instead of the intact vase, explained Tom Holtz, a vertebrate paleontologist at the University of Maryland.

“What’s really nice about the new research is this protein-recovery strategy. It’s the first time the skin of such a big plant-eating dinosaur has been analyzed so deeply,” said Holtz.

“That Dakota’s skin resembles modern vertebrate skin is not surprising but nonetheless comforting,” he added.

Understanding the exact environments that froze Dakota in time may help paleontologists better target future fossil hunts, according to lead study author Manning. (ANI)

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Reinforcement begins at Peking Man site in China

June 27, 2009 By admin Leave a Comment

New Delhi, June 25 (ANI): Reports indicate that reinforcement has begun at the Peking Man site in China to prevent one of its walls from collapsing.

‘Peking Man’ is referred to a group of fossil specimens, hundreds of thousands of years old, discovered in 1923-27 during excavations at Zhoukoudian near Beijing (at that time known as Peking), in China.

Archaeologists are now working for protective excavation at the Peking Man site, focusing on the west section of the cave where the first Peking Man skull was found in Zhoukoudian.

The west section is the only part that has remained untouched since the cave’s discovery.

“Repair work cannot be done without a comprehensive excavation,” said Gao Xing, deputy director and research fellow of the Institute of Vertebrate Paleontology and Palaeoanthropology of the Chinese Academy of Sciences.

However, the wall is slanting towards the ground and risks collapse.

Closer observation over the past month has revealed loose rocks and a crack along its top, which makes it more vulnerable to erosion caused by rain.

Work over the next month will concentrate on areas around the crack and then expand to the whole section between August and October.

“Our ultimate aim is to save the section from further damage so that it might be available for research by future generations,” said Gao.

The site used to be a 20-m wide, 140-m deep cave but the ceiling collapsed long ago.

Chinese archaeologist Pei Wenzhong found the first complete skull at the site in December 1929, together with a large number of stone tools and evidence of fire use by humans.

In 1936, three more skulls were unearthed, and fossils in the caves were found to belong to 40 individuals, with more than 100,000 stone tools.

Controversy remains on various issues, such as if Peking Man was able to control fire, if hunting was part of their lifestyle and the age of Peking Man.

Peking Man, the tool-making “erect man,” was previously believed to have lived in Zhoukoudian Caves about 400,000 to 500,000 years ago.

But, in March, Chinese scientists revealed that using a new radioactive dating method, Peking Man may have lived 200,000 years earlier.

“More intensive research will be done to explain the development of relic deposits in the cave, Gao said.

“The deposits contained traces of humans, ancient animals and changes of natural environment. The excavation will help us understand in a more detailed way when humans settled down in the cave, when they began to use fire, and what and when major climate changes occurred,” he added. (ANI)

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How genetics influences mate selection among humans

May 25, 2009 By admin Leave a Comment

Washington, May 25 (ANI): Shedding new light on how humans choose their partners, a Brazilian scientist has revealed that people have an inherent tendency to get attracted towards genetically opposite individuals.

Professor Maria da Graca Bicalho, head of the Immunogenetics and Histocompatibility Laboratory at the University of Parana, has said that people with diverse major histocompatibility complexes (MHCs) were more likely to choose each other as mates than those whose MHCs were similar.

And she said that this tendency was likely to be an evolutionary strategy to ensure healthy reproduction.

Previous studies have already shown females’ preference for MHC dissimilar mates in many vertebrate species, including humans, and it is also known that MHC influences mating selection by preferences for particular body odours.

In the current study, the researchers decided to investigate mate selection in the Brazilian population, while trying to uncover the biological significance of MHC diversity.

They studied MHC data from 90 married couples, and compared them with 152 randomly generated control couples.

They also counted the number of MHC dissimilarities among those who were real couples, and compared them with those in the randomly-generated ‘virtual couples’.

“If MHC genes did not influence mate selection, we would have expected to see similar results from both sets of couples. But we found that the real partners had significantly more MHC dissimilarities than we could have expected to find simply by chance,” said Bicalho.

Within MHC-dissimilar couples the partners will be genetically different, and such a pattern of mate choice decreases the danger of endogamy (mating among relatives) and increases the genetic variability of offspring.

It’s known that genetic variability is an advantage for offspring,and scientists said that the MHC effect could be an evolutionary strategy underlying incest avoidance in humans and also improving the efficiency of the immune system.

“Although it may be tempting to think that humans choose their partners because of their similarities. Our research has shown clearly that it is differences that make for successful reproduction, and that the subconscious drive to have healthy children is important when choosing a mate,” said Bicalho.

The scientists believe that the findings will help understanding of conception, fertility and gestational failures.

Bicalho will present the findings at the annual conference of the European Society of Human Genetics. (ANI)

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Investing in islands crucial for saving most species in the world

May 18, 2009 By admin Leave a Comment

London, May 18 (ANI): The first worldwide analysis of the importance of different regions for maintaining global biodiversity has determined that an island is about nine times as valuable as an equally large piece of mainland, which makes investing in islands crucial for saving most species in the world.

While it is common knowledge that islands generally house a high number of species that live only in that location, the total diversity of life on most islands is relatively low compared with mainland areas.

“As a result, their importance for conservation efforts hasn’t been clear,” said a team from the Universities of Bonn and Eberswalde, Germany, and the University of California, San Diego.

According to a report in New Scientist, to settle this question, the team calculated a new combined index that takes into account both the number of unique species in a given region and the total number of different species living there.

This “endemism richness” scale measures how much a given area of land contributes to global biodiversity.

The team evaluated the endemism richness of plants and vertebrate land animals for 90 regions covering most of the Earth’s surface.

They discovered that values for islands were 9.5 times higher for plants and 8.1 times higher for vertebrates, compared with similarly sized regions of mainland.

Tropical islands scored highest, with New Caledonia topping the list.

“The results should lead to an increased investment in conservation on tropical island biodiversity hotspots,” said Thomas Brooks, head of Conservation Priorities and Responses at Conservation International’s Center for Applied Biodiversity Science in Arlington, Virginia.

The results should lead to increased investment in conserving tropical island biodiversity hotspots.

According to the researchers, increased investment in islands should be doubly worthwhile because they are likely to lose more habitat from human impact this century than mainland regions. (ANI)

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Poorly regulated US wildlife trade threatens public health and ecosystems

May 3, 2009 By admin Leave a Comment

Washington, May 2 (ANI): In a new report, a team of scientists has determined that the poorly regulated US wildlife trade can lead to devastating effects on ecosystems, native species, food supply chains and human health.

The report has been made by scientists from the Wildlife Trust, Brown University, Pacific Lutheran University, the Centers for Disease Control and Prevention, and the Global Invasive Species Programme.

According to the scientists, the poorly regulated US wildlife trade can lead to devastating effects on ecosystems, native species, food supply chains and human health.

“As our world, in many senses, grows smaller and smaller with the ease of international travel, the network of connections has increased, facilitating the spread of diseases,” said Rita Teutonico, senior advisor for integrative activities in the National Science Foundation’s (NSF) Directorate for Social, Behavioral and Economic Sciences (SBE).

“These scientists report a pattern of trade in wildlife that includes a very large number of animals, coupled with a poor understanding of what species are traded,” said James Collins, NSF Assistant Director for Biological Sciences.

“The findings highlight the need for further research because of the unknown effects these animals and their pathogens can have on native organisms,” he added.

A global trade in wildlife generates hundreds of billions of dollars each year.

The researchers report that during a six-year period from 2000 through 2006, the US imported more than 1.5 billion live animals.

“That’s more than 200 million animals a year – unexpectedly high,” said scientist Peter Daszak, president of the Wildlife Trust, who co-led the research.

The animals collected were from wild populations in more than 190 countries around the world, and were intended for commercial sale in the U.S. – primarily in the pet trade.

“This incredible number of imports is equivalent to every single person in the US owning at least five pets,” said biologist Katherine Smith of Brown University, co-leader of the study.

More than 86 percent of shipments contained animals that were not classified to the level of species, making it impossible to assess the full diversity of animals imported, or calculate the risk of non-native species introductions or disease transmission.

“Shipments are coming in labeled ‘live vertebrate’ or ‘fish’,” said Daszak. “If we don’t know what animals are in there, how do we know which are going to become invasive species or carry diseases that could affect livestock, wildlife – or ourselves?” he added.

“The threat to public health is real, as the majority of emerging diseases come from wildlife,” said Smith. (ANI)

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Frogs provide clues about alcohol’s effects during pregnancy

April 6, 2009 By admin 1 Comment

Washington, Apr 6 (ANI): Scientists have successfully used the African frog Xenopus as a tool to identify important clues about the effects of maternal consumption of alcohol in early pregnancy.

As the Xenopus embryos are large, easy to work with and very responsive to environmental cues, they make for ideal instruments to understand early vertebrate development.

Foetal alcohol spectrum disorder (FASD) and Foetal alcohol syndrome (FAS) cause malformations in babies, including facial defects, short stature, and mental and behavioural abnormalities.

Alcohol consumption prevents normal development by inhibiting the production of retinoic acid.

Normally, the levels of retinoic acid made in different areas of the embryo provide cells with necessary information about their proper location and fate.

In the new research, it has been shown that alcohol steals away the molecules that make retinoic acid and use them for its own process of detoxification, resulting in cellular disorientation during a critical period of development.

The study, provides evidence that the characteristics associated with FASD and FAS come from competition of alcohol for key molecules in a pathway that produce retinoic acid from vitamin A.

Retinoic acid is needed for correct positioning of cells in developing embryos and by preventing its normal production.

Alcohol keeps cells from migrating to their correct positions and maturing properly.

Researchers at the Hebrew University in Israel have found that shutting down a molecule needed to produce retinoic acid, known as retinaldehyde dehydrogenase (RALDH2), increases sensitivity of developing embryos to low doses of alcohol.

On the other hand, more of the molecule RALDH2 protected embryos from the negative effects of alcohol.

The research provides evidence that alcohol ‘hijacks’ RALDH2 molecules for its own breakdown process, and steals it away from its important role in synthesizing positional and maturation cues during development.

The study has been published in Disease Models and Mechanisms (DMM). (ANI)

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Evolution of fins and limbs linked with that of gills

March 24, 2009 By admin Leave a Comment

Washington, March 24 (ANI): A new research has suggested the genetic toolkit that animals use to build fins and limbs is the same genetic toolkit that controls the development of part of the gill skeleton in sharks.

The research was conducted by Andrew Gillis and Neil Shubin of the University of Chicago, and Randall Dahn of Mount Desert Island Biological Laboratory.

“In fact, the skeleton of any appendage off the body of an animal is probably patterned by the developmental genetic program that we have traced back to formation of gills in sharks,” said Andrew Gillis.

“We have pushed back the evolutionary origin of the developmental genetic program that patterns fins and limbs,” he added.

This new finding is consistent with an old theory, often discounted in science textbooks, that fins and (later) limbs evolved from the gills of an extinct vertebrate.

“A dearth of fossils prevents us from definitely concluding that fins evolved from gills. Nevertheless, this research shows that the genetic architecture of gills, fins and limbs is the same,” said Gillis.

The research builds on the breakthrough discovery of the fossil Tiktaalik, a “fish with legs,” by Neil Shubin and his colleagues in 2006.

“This is another example of how evolution uses common developmental programs to pattern different anatomical structures,” said Shubin, who is the Associate Dean of Organismal and Evolutionary Biology at the University of Chicago.

“In this case, shared developmental mechanisms pattern the skeletons of vertebrate gill arches and paired fins,” he added.

The research also showed for the first time that the gill arch skeleton of embryonic skates (a living relative of sharks that has gill rays) responds to treatment with the vitamin A derivative retinoic acid in the same way a limb or fin skeleton does, by making a mirror image duplicate of the structure as the embryo develops.

According to the researchers, the genetic circuitry that patterns paired appendages (arms, legs and fins) has a deep evolutionary origin that actually predates the origin of paired appendages themselves.

“These findings suggest that when paired appendages appeared, the mechanism used to pattern the skeleton was co-opted from the gills,” Gillis said.

“Perhaps we should think of shark gills as another type of vertebrate appendage-one that’s patterned in essentially the same way as fins and limbs,” he added. (ANI)

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Scientists discover elephant shark can see color much like humans can

March 18, 2009 By admin Leave a Comment

Washington, March 18 (ANI): Scientists have discovered that the elephant shark, a primitive deep-sea fish that belongs to the oldest living family of jawed vertebrates, can see color much like humans can.

This discovery may enhance scientists’ understanding of how color vision evolved in early vertebrates over the last 450 million years of evolution.

“It was unexpected that a ‘primitive’ vertebrate like the elephant shark had the potential for color vision like humans,” said Byrappa Venkatesh, a scientist at Singapore’s Institute of Molecular and Cell Biology (IMCB), who with David Hunt, from the Institute of Ophthalmology at University College London (UCL), headed the research team responsible for this surprising discovery.

“The discovery shows that it has acquired the traits for color vision during evolution in parallel with humans,” he added.

The research team found that the elephant shark had three cone pigments for color vision and, like humans, it accomplished this through gene duplication.

Dr. Venkatesh said that the finding underscores the research utility of the elephant shark, which IMCB scientists proposed in 2005 as a valuable reference genome to understand the human genome.

In several scientific publications, Dr. Venkatesh’s team has described research showing that the human DNA sequence was more similar to elephant shark than to any other fish.

According to Dr. Venkatesh, “We expect the sequencing of the whole genome of the elephant shark to be completed by early 2010, the availability of which will then enable scientists to explore the important functional elements in both the human and elephant shark genome that have remained unchanged during the last 450 million years of evolution.” (ANI)

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60-mln yr old giant snake would have made modern anacondas seem like garter snakes

February 6, 2009 By admin Leave a Comment

Washington, Feb 5 (ANI): Scientists have found fossils from a 60-million-year-old South American snake, which is the largest snake on record, and would have outsized even present day anacondas, making them seem like garter snakes in comparison.

Named Titanoboa cerrejonensis by its discoverers, the size of the snake’s vertebrae suggest it weighed 1,140 kilograms (2,500 pounds) and measured 13 meters (42.7 feet) nose to tail tip.

“At its greatest width, the snake would have come up to about your hips,” said geologist David Polly of Indiana University, who identified the position of the fossil vertebrae, which made an estimate possible.

“The size is pretty amazing. We went a step further and asked, how warm would the Earth have to be to support a body of this size?” he added.

Smithsonian Tropical Research Institute geologist Carlos Jaramillo and University of Florida vertebrate paleontologist Jonathan Bloch discovered the fossils in the Cerrejon Coal Mine in northern Colombia, and investigated what the snake’s environment might have been like.

Paleontologist Jason Head of the University of Toronto, the research paper’s lead author, made an estimate of Earth’s temperature 58 to 60 million years ago in an area encompassed by modern-day Colombia.

“Scientists have long known of a rough correlation between a period or epoch’s temperature and the size of its poikilotherms (cold-blooded creatures),” said Paul Filmer, program director in the National Science Foundation (NSF)’s Division of Earth Sciences, which co-funded the research.

“As Earth’s temperature increases, so does the upper size limit on poikilotherms,” he added.

Head estimated that a snake of Titanoboa’s size would have required an average annual temperature of 30 to 34 degrees Celsius (86 to 93 Fahrenheit) to survive.

“Tropical ecosystems of South America were surprisingly different 60 million years ago,” said Bloch. “It was a rainforest, like today, but it was even hotter and the cold-blooded reptiles were substantially larger. The result was, among other things, the largest snakes the world has ever seen,” he added.

The scientists classify Titanoboa as a boine snake, a type of non-venomous constrictor that includes anacondas and boas.

Polly extrapolated the placement of Titanoboa fossil vertebrae by comparing the fossils’ structure to the vertebrae of today’s boine snakes.

Snake vertebrae become larger near a snake’s midsection, but they are also structured differently than vertebrae closer to a snake’s head or tail.

Using a computer model, Polly estimated that the fossil vertebrae originated near Titanoboa’s middle. Therefore, the snake could have been even larger than it appears. (ANI)

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Feathered dinosaur fossil may provide clues to how dinos evolved into modern birds

January 17, 2009 By Rajesh Leave a Comment

Washington, Jan 17 (ANI): Scientists have uncovered the fossil of a primitive feathered dinosaur in China, which is helping them create a better model of how dinosaurs evolved into modern birds.

According to a report in National Geographic News, the winged dinosaur is still in the process of being dated, and might have lived toward the end of the Jurassic period, which lasted from 208 to 144 million years ago.

In many ways, it is “more basal, or primitive, than Archaeopteryx,” said paleontologist Xu Xing at Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology.
rchaeopteryx, the earliest known bird, lived 150 million years ago.

The protobird is “very close to the point of divergence” at which a new branch of winged dinosaurs first took flight, said Xu.

The new species, called Anchiornis huxleyi, was discovered in the ashes of volcanoes that were active during the Jurassic and Cretaceous (144 to 65 million years ago) periods in what is now northeastern China.

Anchiornis, which is Greek for “close to bird,” measured just 13 inches (34 centimeters) from head to tail and weighed about 4 ounces (110 grams).

The dinosaur’s body and forelimbs were covered with feathers, and it “might have had some aerial capability,” Xu said. “Anchiornis is one of the smallest theropod dinosaurs ever uncovered,” he added.

The fossil provides new clues about how feathers, wings, and flight progressively appeared among theropods, along with evidence that certain types of feathered dinosaurs decreased in stature even as their forelimbs became elongated.

The compact structure of Anchiornis “reinforces the deduction that small size evolved early in the history of birds,” Xu explained.

“Anchiornis exhibits some wrist features indicative of high mobility, presaging the wing-folding mechanisms seen in more derived birds,” he said.

“The wrist is a big part of the formation of wings, and pivotal to flight. During flight, steering and flapping greatly depend on the wrist,” Xu added.

Despite this protobird’s relatively advanced feathers and wrist, it is unclear if Anchiornis could actually engage in powered flight.

According to Mark Norell, chairman and curator of the division of paleontology at the American Museum of Natural History in New York, “Behavior and biomechanics are very difficult to determine solely from the fossil record, and perhaps flight is impossible to determine.” (ANI)

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Spookfish uses mirrors for eyes

January 8, 2009 By admin Leave a Comment

Washington, Jan 8 (ANI): A remarkable new discovery has shown the four-eyed spookfish to be the first vertebrate ever found to use mirrors, rather than lenses, to focus light in its eyes.

While the spook fish looks like it has four eyes, in fact it only has two, each of which is split into two connected parts. One half points upwards, giving the spookfish a view of the ocean – and potential food – above.

The other half, which looks like a bump on the side of the fish’s head, points downwards into the abyss below.

These ‘diverticular’ eyes are unique among all vertebrates in that they use a mirror to make the image.

According to Professor Julian Partridge from the University of Bristol, “In nearly 500 million years of vertebrate evolution, and many thousands of vertebrate species living and dead, this is the only one known to have solved the fundamental optical problem faced by all eyes – how to make an image – using a mirror.”

Very little light penetrates beneath about 1000m of water and like many other deep-sea fish the spookfish is adapted to make the most of what little light there is.

At these depths, it is flashes of bioluminescent light from other animals that the spookfish are largely looking for.

The diverticular eyes image these flashes, warning the spookfish of other animals that are active, and otherwise unseen, below its vulnerable belly.

Although the spookfish was first discovered 120 years ago, no one had discovered its reflective eyes until now because a live animal had never been caught.

When Professor Hans-Joachim Wagner from Tuebingen University caught a live specimen off the Pacific island of Tonga, members of his research team used flash photography to confirm the fish’s upward and downward gazes.

Photographs taken by Dr Tammy Frank looking down on the live fish produced eye-shine in the main tubular eyes that point upwards, but not in the diverticular eyes that point downward. Instead, these reflect light when seen from below.

It was when looking at sections of the eye that had been prepared for microscopy that Professor Partridge realised that the diverticular mirrors where something exciting.

The mirror uses tiny plates, probably of guanine crystals, arranged into a multi-layer stack.

Partridge’s computer simulation showed that the precise orientation of the plates within the mirror’s curved surface is perfect for focusing reflected light onto the fish’s retina.

The use of a single mirror has a distinct advantage over a lens in its potential to produce bright, high-contrast images.

That must give the fish a great advantage in the deep sea, where the ability to spot even the dimmest and briefest of lights can mean the difference between eating and being eaten. (ANI)

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