Feathers fly in first bird debate

27 July 2011 Last updated at 20:58 GMT By Matt McGrath Science reporter, BBC World Service An artist's impression of the new creature from China. How will it change our view of the origin of birds? A chicken-sized dinosaur fossil found in China may have overturned a long-held theory about the origin of birds.

For 150 years, a species called Archaeopteryx has been regarded as the first true bird, representing a major evolutionary step away from dinosaurs.

But the new fossil suggests this creature was just another feathery dinosaur and not the significant link that palaeontologists had believed.

The discovery of Xiaotingia, as it is known, is reported in Nature magazine.

The authors of the report argue that three other species named in the past decade might now be serious contenders for the title of "the oldest bird".

Archaeopteryx has a hallowed place in science, long hailed as not just the first bird but as one of the clearest examples of evolution in action.

Wobbling perch: Archaeopteryx is one of the most famous fossils ever unearthed

Discovered in Bavaria in 1861 just two years after the publication of Darwin's Origin of Species, the fossil seemed to blend attributes of both reptiles and birds and was quickly accepted as the "original bird".

But in recent years, doubts have arisen as older fossils with similar bird-like features such as feathers and wishbones and three fingered hands were discovered.

Now, renowned Chinese palaeontologist Professor Xu Xing believes his new discovery has finally knocked Archaeopteryx off its perch.

His team has detailed the discovery of a similar species, Xiaotingia, which dates back 155 million years to the Jurassic Period.

By carefully analysing and comparing the bony bumps and grooves of this new chicken-sized fossil, Prof Xu now believe that both Archaeopteryx and Xiaotingia are in fact feathery dinosaurs and not birds at all.

"There are many, many features that suggest that Xiaotingia and Archaeopteryx are a type of dinosaur called Deinonychosaurs rather than birds. For example, both have a large hole in front of the eye; this big hole is only seen in these species and is not present in any other birds.

Continue reading the main story

Several species discovered in the past decade could now become contenders for the title of most basal fossil bird.

Epidexipteryx - a very small feathered dinosaur discovered in China and first reported in 2008 (above). It had four long tail feathers but there is little evidence that it could fly.

Jeholornis - this creature lived 120 million years ago in the Cretaceous. It was a relatively large bird, about the size of a turkey. First discovered in China, and reported in 2002.

Sapeornis - lived 110 to 120 million years ago. Another small primitive bird about 33 centimetres in length. It was discovered in China and was first reported in 2002.

"Archaeopteryx and Xiaotingia are very, very similar to other Deinonychosaurs in having a quite interesting feature - the whole group is categorised by a highly specialised second pedo-digit which is highly extensible, and both Archaeopteryx and Xiaotingia show initial development of this feature."

The origins of the new fossil are a little murky having originally been purchased from a dealer. Prof Xu first saw the specimen at the Shandong Tianyu Museum. He knew right away it was special

"When I visited the museum which houses more than 1,000 feathery dinosaur skeletons, I saw this specimen and immediately recognised that it was something new, very interesting; but I did not expect it would have such a big impact on the origin of birds."

Other scientists agree that the discovery could fundamentally change our understanding of birds. Prof Lawrence Witmer from Ohio University has written a commentary on the finding.

"Since Archaeopteryx was found 150 years ago, it has been the most primitive bird and consequently every theory about the beginnings of birds - how they evolved flight, what their diet was like - were viewed through the lens of Archaeopteryx.

"So, if we don't view birds through this we might have a different set of hypotheses."

There is a great deal of confusion in the field says Prof Witmer as scientists try to understand where dinosaurs end and where birds begin.

"It's kind of a nightmare for those of us trying to understand it. When we go back into the late Jurassic, 150-160 million years ago, all the primitive members of these different species are all very similar.

"So, on the one hand, it's really frustrating trying to tease apart the threads of this evolutionary knot, but it's really a very exciting thing to be working on and taking apart this evolutionary origin."

Prof Xu first saw the specimen in a museum. He knew right away it was special

Such are the similarities between these transition species of reptiles and birds that other scientists believe that the new finding certainly will not mean the end of the argument.

Prof Mike Benton from the University of Bristol, UK, agrees that the new fossil is about the closest relative to Archaeopteryx that has yet been found. But he argues that it is far from certain that the new finding dethrones its claim to be the first bird.

"Professor Xu and his colleagues show that the evolutionary pattern varies according to their different analyses.

"Some show Archaeopteryx as the basal bird; others show it hopped sideways into the Deinonychosaurs.

"New fossils like Xiaotingia can make it harder to be 100% sure of the exact pattern of relationships."

According to Prof Witmer, little is certain in trying to determine the earliest bird and new findings can rapidly change perspectives.

"The reality is, that next fossil find could kick Archaeopteryx right back into birds. That's the thing that's really exciting about all of this."

View the original article here

First synthetic organ transplant

7 July 2011 Last updated at 16:03 GMT By Michelle Roberts Health reporter, BBC News, in Stockholm The replacement windpipe was grown in the lab Surgeons in Sweden have carried out the world's first synthetic organ transplant.

Scientists in London created an artificial windpipe which was then coated in stem cells from the patient.

Crucially, the technique does not need a donor, and there is no risk of the organ being rejected. The surgeons stress a windpipe can also be made within days.

The 36-year-old cancer patient is doing well a month after the operation.

Professor Paolo Macchiarini from Italy led the pioneering surgery, which took place at the Karolinska University Hospital.

In an interview with the BBC, he said he now hopes to use the technique to treat a nine-month-old child in Korea who was born with a malformed windpipe or trachea.

Professor Macchiarini already has 10 other windpipe transplants under his belt - most notably the world's first tissue-engineered tracheal transplant in 2008 on 30-year-old Spanish woman Claudia Costillo - but all required a donor.

Indistinguishable

The key to the latest technique is modelling a structure or scaffold that is an exact replica of the patient's own windpipe, removing the need for a donor organ.

To do this he enlisted the help of UK experts who were given 3D scans of the 36-year-old African patient, Andemariam Teklesenbet Beyene. The geology student currently lives in Iceland where he is studying for a PhD.

Using these images, the scientists at University College London were able to craft a perfect copy of Mr Beyene's trachea and two main bronchi out of glass.

This was then flown to Sweden and soaked in a solution of stem cells taken from the patient's bone marrow.

After two days, the millions of holes in the porous windpipe had been seeded with the patient's own tissue.

Dr Alex Seifalian and his team used this fragile structure to create a replacement for the patient, whose own windpipe was ravaged by an inoperable tumour.

Despite aggressive chemotherapy and radiotherapy, the cancer had grown to the size of a golf ball and was blocking his breathing. Without a transplant he would have died.

During a 12-hour operation Professor Macchiarini removed all of the tumour and the diseased windpipe and replaced it with the tailor-made replica.

The bone marrow cells and lining cells taken from his nose, which were also implanted during the operation, were able to divide and grow, turning the inert windpipe scaffold into an organ indistinguishable from a normal healthy one.

And, importantly, Mr Beyene's body will accept it as its own, meaning he will not need to take the strong anti-rejection drugs that other transplant patients have to.

Professor Macchiarini said this was the real breakthrough.

"Thanks to nanotechnology, this new branch of regenerative medicine, we are now able to produce a custom-made windpipe within two days or one week.

"This is a synthetic windpipe. The beauty of this is you can have it immediately. There is no delay. This technique does not rely on a human donation."

He said many other organs could be repaired or replaced in the same way.

A month on from his operation, Mr Beyene is still looking weak, but well.

Sitting up in his hospital bed, he said: "I was very scared, very scared about the operation. But it was live or die."

He says he is looking forward to getting back to Iceland to finish his studies and then returning to his home in Eritrea where he will be reunited with his wife and young family, and meet his new three-month-old child.

He says he is eternally grateful to the medical team that has saved his life.

View the original article here

Ice mission produces first map

By Jonathan Amos Science correspondent, BBC News, Paris This is the best view we have yet had of the thickness of sea-ice across the entire Arctic Ocean basin.

It is the first fully processed map from Europe's new Cryosat spacecraft.

It only covers the months of January and February, but the UK team behind the data says it can now roll out the information on a continuous basis.

The extent of Arctic sea-ice has become a major issue in recent years, with summer melting appearing to outstrip what many climate models had predicted.

But a proper assessment of the status of the sea-ice requires knowledge also about its thickness - something scientists have only recently had the tools to measure from space.

"Some years the wind will push the ice out of the way or pile it up, and it may look from the area coverage like it's all melted," explained the Cryosat mission's principal investigator, Professor Duncan Wingham.

The old ice in the Arctic tends to have rough ridges

"But it's only when you combine the area coverage information with the thickness information that you get the product - volume. And that's what you really need to know to answer the question about melting," he told BBC News.

Professor Wingham presented Cryosat's first ice map here at the Paris Air Show in Le Bourget, a major event in the space calendar.

The European Space Agency (Esa) launched its "ice explorer" last year. It carries one of the highest resolution synthetic aperture radars ever put in orbit.

The instrument sends down pulses of microwave energy that bounce off both the top of the Arctic sea-ice and the water in the cracks, or leads, which separate the floes.

By measuring the difference in height between these two surfaces, the Cryosat team is able, using a relatively simple calculation, to work out the overall volume of the marine ice cover in the far north.

Wingham's group at the Centre for Polar Observation and Modelling, University College London, has spent the past year learning how to interpret the radar data and turn it into a form that the research community can use.

Continue reading the main story Cryosat's radar has the resolution to see the Arctic's floes and leadsSome 7/8ths of the ice tends to sit below the waterline - the draftThe aim is to measure the freeboard - the ice part above the waterlineKnowing this 1/8th figure allows Cryosat to work out sea ice thicknessThis has involved calibrating the instrument and then validating its output by comparing it with independent assessments.

One such assessment employed a German Alfred Wegener Institute (AWI) aeroplane.

It obtained thickness information by flying a laser altimeter to record the distance to the top of the ice and a conductivity sensor to identify the location of seawater on the underside of the floes. Being an aeroplane, it could only record limited lines of data, but these strongly correlated with the Cryosat observations.

Another independent assessment called on a different type of radar satellite instrument known as a scatterometer, which, as its name suggests, looks at how much of the energy beamed down from space is reflected back or scattered away. This type of instrument can discern the thin flat seasonal ice from the rough terrains associated with floes that have been around for many years.

Again, what the scatterometer saw with its approach was an excellent match for the Cryosat map.

The Cryosat team has been "in the field" to validate the satellite's measurements

"We're now processing the rest of the Cryosat data to get it to the same standard as we're showing you here," said CPOM researcher Dr Katharine Giles. "Then we will use that data to look at how the ice cover is changing. This is only two months of data - and we're very excited to have our first map - but we need to compare year-on-year changes."

Scientists already have a number of insights on sea-ice thickness in the Arctic - from buoys, from submarine sonar data, from field expeditions, from aircraft sorties such those by the AWI, and from previous generations of satellite radar and laser altimeters. But Cryosat should be a big boost to that data haul, not least because it sees the entire Arctic basin, right up to two degrees from the pole.

In addition to its sea-ice mission, Cryosat is also tracking changes in land-ice.

For this, the radar instrument carries a second antenna. By listening to the radar echoes with an additional device offset from the first by about a metre, the satellite can sense much better the shape of the ice below, returning more reliable information on slopes and ridges.

This is especially important in Greenland and Antarctica where past missions have struggled to discern events at the edges of the ice sheets - the very locations where some of the biggest, fastest changes have been taking place.

Here at Le Bourget, an elevation model built from Cryosat data was displayed of Antarctica. Again, this covered just the months of January and February this year.

• As with the Arctic sea-ice map, this height model of Antarctica incorporates just two months of data at the start of the year

• The outer ring shows the closest older satellites could get to the pole. The inner hole is the only portion unseen by Cryosat

• The exaggerated model has been sliced open like a cake to show the position of the Antarctic bedrock under the ice

• By subtracting ice-surface height from bedrock height, Cryosat can derive ice thickness across the entire continent

Cryosat was given an initial mission plan to 2013, but engineers fully expect it to keep working until perhaps 2017. To pay for that extension, Esa will need to get new funding from Europe's space ministers when they meet for their big conference in Italy next year.

Dr Volker Liebig, the director of Earth observation at the agency, said Cryosat had already made a compelling case for the additional support - and perhaps for something even bigger down the line.

"Cryosat is a science mission that is part of Esa's Envelope Earth observation programme. I think it has the makings of a [on-going] operational mission," he told the air show presentation.

"The need for this data will not stop when we retire this mission. The first step is to run Cryosat for as long as possible, but then we have a couple of missions that have the potential to become operational - and Cryosat is one of them."

Jonathan.Amos-INTERNET@bbc.co.uk

View the original article here

First images of unconscious brain

13 June 2011 Last updated at 22:55 GMT By Jennifer Carpenter Science reporter, BBC News These images capture a patient's brain activity the moment they slip into unconsciousness

For the first time researchers have monitored the brain as it slips into unconsciousness.

The new imaging method detects the waxing and waning of electrical activity in the brain moments after an anaesthetic injection is administered.

As the patient goes under, different parts of the brain seem to be "talking" to each other, a team told the European Anaesthesiology Congress in Amsterdam.

But they caution that more work is needed to understand what is going on.

The technique could ultimately help doctors pinpoint damage in the brains of people suffering from stroke and head injury.

"Our jaws just hit the ground," said anaesthesiologist Professor Brian Pollard from Manchester Royal Infirmary on seeing the images for the first time.

"I can't tell you the words we used as it wouldn't be polite over the phone."

Cross talk

Although regions of the brain seem to be communicating as "consciousness fades", Professor Pollard cautions that it is early days and that he and his team from the University of Manchester still have many brain scans to analyse before they can say anything conclusive about what is happening.

The finding supports a theory put forward by Professor Susan Greenfield, from the University of Oxford, that unconsciousness is a process by which different areas of the brain inhibit each other as the brain shuts down.

Fully operable

The new technique, called Functional Electrical Impedance Tomography by Evoke Response (fEITER), is more compact than other brain imaging techniques, such as functional magnetic resonance imaging (fMRI), and so is easily transported into the operating theatre.

It involves attaching tens of electrodes to the patient's head, which send low electrical currents through the skull. The currents are interrupted by the brain's tissues and electrical signals.

Professor Pollard explained that the brain's structures should not change over a minute-long scan, and so any differences that he and his team see as the patient falls asleep must therefore be due to changes in their brain's activity.

It is hoped that this technique could be used to learn about the nature of consciousness, but it is also likely to help doctors make headway in monitoring the health of a person's grey matter after they have suffered a head injury or stroke.

View the original article here