Ancient four-flippered reptile flapped like a penguin

December 17, 2015

Ancient four-flippered reptile flapped like a penguin. Credit: Liu et al. 10.1371/journal.pcbi.1004605

The puzzle of the plesiosaur has been revealed by computer simulations showing how the ancient animals used their unusual four-flippered body to swim through the ocean.

The study published this week in PLOS Computational Biology by computer scientists, led by Greg Turk from the Georgia Institute of Technology and in collaboration with paleontologist Adam Smith at Wollaton Hall, Nottingham Natural History Museum, investigates the long-standing puzzle of plesiosaur swimming.

The researchers find that the most effective swimming motion for the plesiosaur is flapping the two front flippers in an underwater flight motion, similar to that of a penguin. Surprisingly, however, the simulations revealed that the rear flippers would not have substantially increased their forward speed. Instead, the back flippers of plesiosaurs were probably used for steering and stability.

Plesiosaurs are an extinct group of marine reptiles that were apex predators for 135 million years during the age of the dinosaurs. Their unique four-flipper body plan is unlike any modern-day swimming animal and paleontologists have debated their possible swimming style since the first complete plesiosaur skeleton was described in 1824. The study uses computer simulations to help resolve this question. Thousands of different swimming motions were simulated to identify the most effective swimming strategy for the plesiosaur body plan.

Future computer simulations could be used to discover the degree of agility that plesiosaurs gain from their rear flippers. The method can also be applied to understand the swimming motion of other prehistoric animals.Ancient four-flippered reptile flapped like a penguin. Credit: Liu et al. 10.1371/journal.pcbi.1004605

"Plesiosaur swimming has remained a mystery for almost 200 years, so it was exciting to see the plesiosaur come alive on the computer screen" said Smith.

"Our results show that the front limbs provide the powerhouse for plesiosaur propulsion while the hind limbs are more passive" said Smith.

More information: Liu S, Smith AS, Gu Y, Tan J, Liu CK, Turk G (2015) Computer Simulations Imply Forelimb-Dominated Underwater Flight in Plesiosaurs. PLoS Comput Biol 11(12): e1004605. DOI: 10.1371/journal.pcbi.1004605

Journal reference: PLoS Computational Biology
Provided by: Public Library of Science  

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B.C. family’s fossil find identified as 25-million-year-old flightless bird

Researchers identified the animal as a new species of a plotopterid, a long-extinct penguin or cormorant-like bird never before found in Canada.

THE CANADIAN PRESS

An artist's rendition shows a Stemec suntokum, a type of plotopterid which lived 25 million years ago. 

By: Terri Theodore The Canadian Press,  

Published on Tue Dec 15 2015

 

VICTORIA—A family out for a stroll on southern Vancouver Island stumbled upon the extraordinary fossilized remains of a 25-million-year-old flightless bird that has created a flap in the world of paleontology.

The fossil was in good enough condition for researchers to identify the animal as a new species of a plotopterid, a long-extinct penguin or cormorant-like bird never before found in Canada.

A collarbone from the bird was found inside a slab of rock on a Sooke, B.C., beach.

It’s only the second set of fossilized bird bones found on southern Vancouver Island since 1895, said bird expert Gary Kaiser of the Royal B.C. Museum.

Fossils of birds are extremely rare because the fragile and hollow bones don’t hold up to crushing weight, acidic soils and elements like other fossils do.

“They get broken up, crushed easily,” Kaiser said in an interview Tuesday. “The bones simply dissolve. They disappear.”

In this case, the sandstone and lack of acid in the water seemed to preserve the fossil, he said.

A father, daughter and son were out for a walk two years ago when they found the bone in a slab of rock that had fallen from the nearby cliffs, he said.

The daughter spotted the fossil. Her brother carried the slab off the beach, before the father brought it to the museum.

Next to a skull, the collarbone is the best bone to find because it sits at the shoulder where the wings function and where the collar blade, arm bone and sternum are attached.

“It is the most informative bone in a bird skeleton. It tells you more than anything else about what the bird does for a living,” Kaiser said.

The long, skinny bone wasn’t anything like he had ever seen before.

“Right away, I knew it was an unusual bone,” he said, noting that’s when he linked it to the plotopterid fossil.

Relatives of the bird have been found in Japan and in Oregon and California, but none has been as small.

“Of those several hundred birds, all but two of them are huge. I mean they’re birds that probably weighed 200 kilograms when they were alive and stood six-foot tall,” Kaiser said.

This animal was about the size of a cormorant.

Kaiser and his colleague Junya Wantanabe of Kyoto University named the bird Stemec suntokum because it’s a new species. The name means long-necked waterbird in the language of the T’Sou-Ke First Nation who live in the area.

Kaiser said he believes that if they had the fossil’s brain case the animal would look like a penguin, but an American man who studies plotopterids is convinced they are more like cormorants.

“It’s a bit of a fight, but not unusual in biology because there’s no way of telling,” he added.

The discovery announcing the new species has been published in the online journal Palaeontologia Electronica.

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Penguins filmed in epic underwater fight stealing a large squid

16 December 2015

A gentoo penguin darting through the sea off the Falkland Islands catches a large squid in its bill.
The prey is too big to swallow whole – and is suddenly snatched away by a second penguin. A third penguin joins the scuffle, while the first makes a last-ditch bid for its catch. A tug of war ensues, and the hapless squid is torn in two.

This underwater brawl was captured on a video camera taped to the back of the second penguin, revealing this unexpected foraging behaviour for the first time. “This is completely new behaviour, not just for gentoo penguins but for penguins in general,” says Jonathan Handley, a doctoral student at Nelson Mandela Metropolitan University in Port Elizabeth, South Africa.

Handley used high-definition video cameras waterproofed with custom-made Perspex casings, which functioned perfectly to depths of more than 200 metres.

Video: Squid-hunting penguins caught in rare underwater food fight

“These images are unique in that they were captured underwater in a situation that would have been unobservable without this technology,” says Norman Ratcliffe, a seabird ecologist at the British Antarctic Survey in Cambridge, UK. “It is interesting that the interaction was over a squid: a large and difficult-to-capture prey item that is clearly worth fighting for.”

We already knew that penguins stole pebbles from each other’s nests and have records of seabirds fighting over food – behaviour known as kleptoparasitism.

Population centre

The Falkland Islands are home to around 130,000 breeding pairs of gentoo penguins – the world’s largest population of this species. Handley studied them over three breeding seasons from 2011 with the assistance of Falklands Conservation, a local non-governmental organisation.

He says a large squid would be prize prey for a penguin, providing high-energy food for both a parent and chick, and reducing foraging time. “The majority of their prey is small and quickly consumed,” he says.

But he believes it is unlikely that gentoos specialise in becoming food thieves. They would probably only steal food that other penguins need to handle for a long time such as a huge squid, he says, allowing them the opportunity to steal it.

Handley says the theft of nesting material such as pebbles and plants – which provide eggs with thermal insulation and protection from rain and meltwater – has been observed when in short supply in penguin colonies belonging to the Pygoscelis genus (better known as brush-tailed penguins), which includes gentoos.

So why do they do it? “Individuals able to acquire more resources, including both food and nesting material, will be able to provide better parental care for offspring, thus increasing the offspring’s chance to survive until fledging,” Handley says.

Journal reference: Polar Biology, DOI: 10.1007/s00300-015-1772-2

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Penguin cam captures hunt for prey

Little penguins work together to hunt schooling prey

Date:

December 16, 2015

Source:

PLOS

Summary:

Little penguins were more likely to work together to hunt schooling prey than solitary prey, according to observations made using animal-borne cameras.

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This is a photograph of penguins foraging as a group.

Credit: John Arnould, Deakin University

Little penguins were more likely to work together to hunt schooling prey than solitary prey, according to observations made using animal-borne cameras published Dec. 2, 2015 in the open-access journal PLOS ONE by Grace Sutton from the Deakin University, Australia, and colleagues.

Group foraging in cooperative animals provides predators with advantages over prey, but for less cooperative colonial-breeding predators, like the little penguin, the benefits of group foraging are less clear due to the potential for competition between penguins. The authors of this study used animal-borne cameras on 21 little penguins from two breeding colonies in south-eastern Australia to determine the prey types, hunting strategies, and success of little penguins, a small, marine predator that extensively forages with other little penguins.

The researchers found that little penguins had a higher probability of associating with each other when hunting schooling prey than when encountering solitary prey. Surprisingly, individuals were no more successful at capturing schooling prey than solitary prey. However, success preying on schooling fish was similar or greater when individual penguins hunted on their own rather than together. The authors suggest that individual penguins may trade-off the potential benefits of solitary hunting to increase the probability of detecting prey by associating with other little penguins.

Grace Sutton says: "This study showed little penguins gained no benefit in capturing prey when from hunting in groups, suggesting individuals may forage in groups to improve detection of prey or avoid predation but, once they find prey, it is every penguin for themselves."

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Story Source:
The above post is reprinted from materials provided by PLOS. Note: Materials may be edited for content and length.

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Journal Reference:

1. Grace J. Sutton, Andrew J. Hoskins, John P. Y. Arnould. Benefits of Group Foraging Depend on Prey Type in a Small Marine Predator, the Little Penguin. PLOS ONE, 2015; 10 (12): e0144297 DOI: 10.1371/journal.pone.0144297

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PLOS. "Penguin cam captures hunt for prey: Little penguins work together to hunt schooling prey." ScienceDaily. ScienceDaily, 16 December 2015. <www.sciencedaily.com/releases/2015/12/151216151605.htm>.

Researchers find that Australian and New Zealand little penguins are distinct species

Public Release: 14-Dec-2015

University of Otago

IMAGE:

A team of researchers from New Zealand's University of Otago and the University of Tasmania has discovered that Australian and New Zealand little penguins represent two distinct species, rather than one.

Credit

Dr Stefanie Grosser

Scientists had previously wondered about the relationships between populations of the penguin (popularly known as little blue penguins or fairy penguins) found on either side of the Tasman. The trans-Tasman team used genetic techniques to compare populations from both countries, and surprisingly found that they are not the same species.

"We found a very strong pattern, where New Zealand has its own distinctive genetic group that is clearly very different from the Australian penguin populations," says Dr Stefanie Grosser, who carried out the study as part of her Otago PhD project.

Similar to their human counterparts, the two species also seem to have developed their own 'accents'. Other researchers have previously shown that calls differ between Australian and New Zealand little penguins and females prefer the calls of males of their own species. "You could say the Aussies like hearing 'feesh', while 'fush' sounds better to Kiwi ears," Dr Grosser jokes.

"The recognition of unique penguin species on both sides of the Tasman highlights the importance of managing and conserving them separately," she says.

Another unexpected finding of the study was the discovery that the Australian species -- Eudyptula novaehollandiae -- is surprisingly also present in Otago, in the remote southeast corner of New Zealand's South Island. "Our genetic data suggest that the Otago and Australian populations are quite closely related," says Dr Grosser.

The team is currently working to better establish the history of the Otago population using ancient DNA. "This research highlights that there is still much to be discovered about our region's unique wildlife," says Professor Jon Waters, who was involved in the study. "The new recognition of endemic species -- unique to our region -- is crucial for managing our natural heritage."

###

The research was funded by the Marsden Fund and Allan Wilson Centre and published this week in the international journal PLOS ONE.

The article is available here: http://dx.plos.org/10.1371/journal.pone.0144966

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Influence of Earth's history on the dawn of modern birds

New time tree indicates that avian evolution was molded by climate change and plate tectonics

Date:

December 11, 2015

Source:

American Museum of Natural History

Summary:

The evolution of modern birds was greatly shaped by the history of our planet's geography and climate. New research finds that birds arose in what is now South America around 90 million years ago, and radiated extensively around the time of the Cretaceous-Paleogene extinction. The new research suggests that birds in South America survived this event and then moved around the world via multiple land bridges while diversifying during periods of global cooling.

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Modern day great blue herons. Birds arose in what is now South America around 90 million years ago, and radiated extensively around the time of the Cretaceous-Paleogene extinction event that killed off the non-avian dinosaurs, according to new research.

Credit: © SunnyS / Fotolia

 

New research led by the American Museum of Natural History reveals that the evolution of modern birds was greatly shaped by the history of our planet's geography and climate. The DNA-based work, published today in the journal Science Advances, finds that birds arose in what is now South America around 90 million years ago, and radiated extensively around the time of the Cretaceous-Paleogene extinction event that killed off the non-avian dinosaurs. The new research suggests that birds in South America survived this event and then started moving to other parts of the world via multiple land bridges while diversifying during periods of global cooling.

"Modern birds are the most diverse group of terrestrial vertebrates in terms of species richness and global distribution, but we still don't fully understand their large-scale evolutionary history," said Joel Cracraft, a curator in the Museum's Department of Ornithology and co-author of the paper. "It's a difficult problem to solve because we have very large gaps in the fossil record. This is the first quantitative analysis estimating where birds might have arisen, based on the best phylogenetic hypothesis that we have today."

Cracraft and lead author Santiago Claramunt, a research associate in the Museum's Department of Ornithology, analyzed DNA sequences for most modern bird families with information from 130 fossil birds to generate a new evolutionary time tree.

"With very few exceptions, fossils of modern birds have been found only after the Cretaceous-Paleogene (K-Pg) extinction," said Claramunt. "This has led some researchers to suggest that modern birds didn't start to diversify until after this event, when major competitors were gone. But our new work, which agrees with previous DNA-based studies, suggests that birds began to radiate before this massive extinction."

After the K-Pg extinction, birds used two routes to cover the globe: first, to North America across a Paleogene Central American land bridge and then to the Old World; and second, to Australia and New Zealand across Antarctica, which was relatively warm at that time.
Claramunt and Cracraft also found that bird diversification rates increased during periods of global cooling.

"When the Earth cools and dries, fragmentation of tropical forests results in bird populations being isolated," Cracraft said. "Many times, these small populations will end up going extinct, but fragmentation also provides the opportunity for speciation to occur and for biotas to expand when environments get warm again. This work provides pervasive evidence that avian evolution has been influenced by plate tectonics and environmental change."

This work was supported by the Museum's F. M. Chapman Fund and the U.S. National Science Foundation, award #s 1241066 and 1146423.

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Story Source:
The above post is reprinted from materials provided by American Museum of Natural History. Note: Materials may be edited for content and length.

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Journal Reference:

1. S. Claramunt, J. Cracraft. A new time tree reveals Earth historys imprint on the evolution of modern birds. Science Advances, 2015; 1 (11): e1501005 DOI: 10.1126/sciadv.1501005

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American Museum of Natural History. "Influence of Earth's history on the dawn of modern birds: New time tree indicates that avian evolution was molded by climate change and plate tectonics." ScienceDaily. ScienceDaily, 11 December 2015. <www.sciencedaily.com/releases/2015/12/151211145038.htm>.

 

 

 

New Study Shows Surprising Path of Bird Evolution

Archaeopteryx bavarica, Paläontologisches Museum, München.
Credit: Luidger/Wikipedia

New research led by the American Museum of Natural History reveals that the evolution of modern birds was greatly shaped by the history of our planet's geography and climate. The DNA-based work, published today in the journal Science Advances, finds that birds arose in what is now South America around 90 million years ago, and radiated extensively around the time of the Cretaceous-Paleogene extinction event that killed off the non-avian dinosaurs. The new research suggests that birds in South America survived this event and then started moving to other parts of the world via multiple land bridges while diversifying during periods of global cooling.

"Modern birds are the most diverse group of terrestrial vertebrates in terms of species richness and global distribution, but we still don't fully understand their large-scale evolutionary history," said Joel Cracraft, a curator in the Museum's Department of Ornithology and co-author of the paper. "It's a difficult problem to solve because we have very large gaps in the fossil record. This is the first quantitative analysis estimating where birds might have arisen, based on the best phylogenetic hypothesis that we have today."

Cracraft and lead author Santiago Claramunt, a research associate in the Museum's Department of Ornithology, analyzed DNA sequences for most modern bird families with information from 130 fossil birds to generate a new evolutionary time tree.

"With very few exceptions, fossils of modern birds have been found only after the Cretaceous-Paleogene (K-Pg) extinction," said Claramunt. "This has led some researchers to suggest that modern birds didn't start to diversify until after this event, when major competitors were gone. But our new work, which agrees with previous DNA-based studies, suggests that birds began to radiate before this massive extinction."

After the K-Pg extinction, birds used two routes to cover the globe: first, to North America across a Paleogene Central American land bridge and then to the Old World; and second, to Australia and New Zealand across Antarctica, which was relatively warm at that time.

Claramunt and Cracraft also found that bird diversification rates increased during periods of global cooling.

"When the Earth cools and dries, fragmentation of tropical forests results in bird populations being isolated," Cracraft said. "Many times, these small populations will end up going extinct, but fragmentation also provides the opportunity for speciation to occur and for biotas to expand when environments get warm again. This work provides pervasive evidence that avian evolution has been influenced by plate tectonics and environmental change."

Reference:
S. Claramunt, J. Cracraft. A new time tree reveals Earth historys imprint on the evolution of modern birds. Science Advances, 2015; 1 (11): e1501005 DOI: 10.1126/sciadv.1501005

Note: The above post is reprinted from materials provided by American Museum of Natural History.

source

The Social Dynamics of #Penguin Huddles Are More Complex Than We Thought

Jennifer Ouellette

12/07/15 

 

Emperor penguins huddle together for warmth during those punishing Antarctic storms, taking turns being at the center of the huddle. The social dynamics behind those huddles turns out to more complicated than previously thought. 

Researchers at the University of Strasbourg in France studied 3000 breeding pairs of penguins in the Pointe Geologie Archipelago colony in Antarctica during the 2005, 2006 and 2008 seasons. They just published their results in the latest issue of the journal Animal Behavior. Most notably, they found that it only takes a single penguin leaving the huddle to cause it to break apart.

That’s in keeping with earlier work on how a single penguin can set off a “traveling wave” through the huddle. A few years ago, Daniel Zitterbart was in Antarctica conducting seismology research when he noted the huddling behavior of male emperor penguins, tasked with incubating the colony’s eggs. He thought it looked a lot like cell dynamics, so he videotaped the huddles and studied the time-lapsed footage when he returned home to the Alfred Wegener Institute in Germany. He found that huddled penguins don’t stand completely still. They move every minute or so, and when they do, all their nearest neighbors move with them.

Zitterbart likened the behavior to a traveling wave. Huddled emperor penguins move in similar patterns as heavy traffic inching along the freeway. When he adapted traffic flow models to the penguins’ behavior, he found that any given penguin can trigger a traveling wave; all it needs to do is step about 2 centimeters in any direction, and all its closest neighbors will do the same. He speculated that this so-called “threshold distance” is related to the animal’s layer of feathers: it’s twice as thick, allowing the huddle to pack together as densely as possible for warmth without crushing that feathery insulation.

Check out Zitterbart’s model of huddle behavior:

Given the bone-chilling temperatures the harsh Antarctic environment can reach, you’d think that once penguins get into a good warm huddle, they’d stay there. Instead, it seems that most huddles don’t last that long, according to Strasbourg scientist Andre Ancel, lead author on the latest study. He and his colleagues found that while some huddles held formation for several hours, others lasted just 10 minutes or so. On average, the huddles would break up around the 50-minute mark.

Why? It might have something to do with dispersing all that pent-up heat. It makes sense when you think about how the heat from all those penguin bodies must be building up, especially at the center of the huddle. Ancel et al. estimate that temperatures can be as high as 100 degrees there — a bit too toasty for a penguin’s comfort. In fact, “The breakup of huddles is sometimes accompanied by a haze of warm air rising over the colony, which indicates a significant dissipation of heat,” Ancel et al. write. They even observed some penguins eating snow after getting out of the huddle, presumably to cool off faster.

So the penguin at the center of the huddle doesn’t really have the sweetest spot, at least not once the heat starts to build. Yet the Strasbourg scientists found that while it only took one penguin to start a chain reaction that broke up the huddle — or, in one memorable case, two penguins getting into a fight — that penguin was rarely the one in the center. Usually it was a penguin on the edge of the huddle that peeled away first.

References:
Ancel, Andre et al. (2015) “New insights into the huddling dynamics of emperor penguins,” Animal Behaviour 110: 91-98.
Gerum, R.C. et al. (2013) “The origin of traveling waves in an emperor penguin huddle,” New Journal of Physics 15.
Gilbert, C. et al. (2006) “Huddling behavior in emperor penguins: dynamics of huddling,” Physiology & Behavior 88: 479-488.
Waters, A., Blanchette F., and Kim, A.D. (2012) “Modeling huddling penguins,” PLoS ONE 7: e50277.
Zitterbart, D.P. et al. (2011) “Coordinated movements prevent jamming in an Emperor penguin huddle,” PLoS ONE 6: e20260.

[Via Mental Floss]

Image: Still from PBS’ The Gathering Swarms (2014).

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A single #penguin can break up a huddle

by Sarah Zielinski

December 3, 2015

Emperor penguins gather together to breed. When conditions are harsh, they huddle together for warmth. But those huddles can quickly come apart, a new study finds.

MemoryCatcher/Pixabay 

In the 2005 documentary March of the Penguins, there’s a scene that shows a group of male emperor penguins hunkered down through an Antarctic storm. The birds are incubating eggs, balanced on their feet, while the females have gone off to feed. To stay warm, the penguins huddle together, rotating from the inside to the outside of the huddle, and back again, to make sure that no one gets too cold — a seemingly simple solution to keep everyone cozy.

It turns out, huddles are far more complicated than that.

Or at least, the huddles that form among Antarctica’s Pointe Géologie Archipelago colony are. André Ancel of the University of Strasbourg in France and colleagues studied the 3,000 or so breeding pairs that live in this colony during the 2005, 2006 and 2008 breeding seasons, counting birds and recording their actions with pictures and video. Huddles, they found, are only temporary arrangements lasting a few hours at most. And a single penguin can break up the group in less than two minutes, the researchers report in the December Animal Behaviour.

Emperor penguins aren’t the only animals that huddle, but they may be the best at it. Densities can reach as high as eight to 10 birds per square meter, and this behavior helps them survive the extreme cold and wind found in Antarctica. Jamming together lets the birds conserve heat, but they can easily generate too much. As the birds breathe out, the air around them can reach temperatures as high as 37.5° Celsius, well above the 20° C upper limit for the birds’ comfort. The growth and decay of huddles occurs because of the need to manage this heat, Ancel and colleagues contend.

As the air temperature decreases, birds gather together in small huddles, looking for the nearest source of warmth. If there is less solar radiation or winds kick up, the birds take their time to find a big huddle and join the group. But huddles may not last long. The researchers recorded some huddles that lasted several hours, but others broke up after only a dozen minutes. On average, they found, huddles broke up after only 50 minutes.

Ancel and his team had hypothesized that huddle breakups would most often be initiated from the center, where penguins were the warmest. But that only happened once. More often, it was an individual near the edge that initiated the breakup — usually as he departed, but in one case two penguins started it by getting into a fight. Within two minutes of initiation, the breakup was complete, and the huddle dispersed.

The researchers think that the huddle breakups help to dissipate heat. “The breakup of huddles is sometimes accompanied by a haze of warm air rising over the colony, which indicates a significant dissipation of heat,” they note. And some birds that leave a huddle have been seen eating snow, possibly because they needed to cool down after being in the group.

Scientists once thought that the penguin huddle was simply a way to conserve energy, but it may be that it’s more complex, a way to thermoregulate through social interaction. Ancel and colleagues caution, though, other factors may be involved for emperor penguins elsewhere in Antarctica. 

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The anti-icing tricks of #penguins

Date:

November 23, 2015

Source:

American Physical Society's Division of Fluid Dynamics

Summary:

Antarctic penguins live in a bitterly cold place, where the air temperature can drop to -40 degrees Celsius and the winds can hurtle at speeds of 40 meters per second. Although these birds routinely hop in and out of the water in sub-freezing temperatures, they manage to keep ice from coating their feathers. Now researchers have examined penguin feathers in extreme detail and think they know the penguins' anti-icing trick: a combination of nanostructures and a special oil make Antarctic penguin feathers ultra-water-repelling, or superhydrophobic.

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Diving penguins (Antarctica).

Credit: © alekseev / Fotolia

 

Antarctic penguins live in a bitterly cold place, where the air temperature can drop to -40 degrees Celsius and the winds can hurtle at speeds of 40 meters per second. Although these birds routinely hop in and out of the water in sub-freezing temperatures, they manage to keep ice from coating their feathers.

Now researchers have examined penguin feathers in extreme detail and think they know the penguins' anti-icing trick: a combination of nanostructures and a special oil make Antarctic penguin feathers ultra-water-repelling, or superhydrophobic. Droplets of water on the feathers bead up so much that's it's difficult for heat to flow out of the droplet, and the water will roll off before it has time to freeze.
The researchers will present their findings at the annual meeting of the American Physical Society's Division of Fluid Dynamics, held Nov. 22-24 in Boston, Mass.

Pirouz Kavehpour, a professor in the Department of Mechanical and Aerospace Engineering at UCLA, first got interested in penguin feathers while watching a nature documentary on the famous black and white birds. "I noticed the penguins were coming out of very cold water, and sitting in very cold temperatures, and it was curious that no ice formed on their feathers," he said.

Kavehpour got in touch with Judy St. Leger, a world expert on penguins, who confirmed that indeed no one had ever observed ice on the feather coat of healthy penguins. To find out what the penguins' anti-icing secret was, the two scientists and their colleagues studied penguin feathers, donated by San Diego SeaWorld, using Scanning Electron Microscopy.

They discovered that the feathers had tiny pores that trap air and make the surface hydrophobic. In addition, the penguins apply an oil, which is produced by a gland near the base of their tail, to their feathers. The combination of the nano-sized pits and the preen oil makes the feathers superhydrophobic.

On superhydrophobic surfaces, water droplets bead up and sit on the surface almost like spheres. Kavehpour and his colleagues propose that it's the sphere-like geometry that delays ice formation, since heat has a hard time flowing out of the water droplet if the droplet does not make much contact with the surface.

"Heat flow could be compared to traffic. If you have a freeway that turns into a tiny, two-lane road, the traffic will back up. Similarly, heat does not flow well from the large cross-section of the middle of the drop to the small cross-section where the drop makes contact with the feather," Kavehpour said.

The scientists looked most extensively at the feathers of the gentoo penguin, which lives in Antarctica and the southern-most parts of South America. They also compared the gentoo feathers to feathers from the Magellanic penguin, which lives in warmer climates farther north in Chile, Argentina and even Brazil. They found that the warmer weather penguins lacked the small pores on their feathers, and that the birds also produced a different type of preen oil that was not as hydrophobic.

Penguin's anti-icing solutions could help humans solve some of our own problems with ice. For example, ice on an airplane's wings, flaps and rudder can alter the aerodynamic properties of the plane and even cause it to crash. Airlines spend lots of time and money applying chemical de-icers to planes that fly in winter weather. Superhydrophobic surfaces inspired by penguins might be cheaper, longer-lasting and more environmentally friendly.

"It's a little ironic that a bird that doesn't fly could one day help airplane fly more safely," Kavehpour said.

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Story Source:
The above post is reprinted from materials provided by American Physical Society's Division of Fluid Dynamics. Note: Materials may be edited for content and length.

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American Physical Society's Division of Fluid Dynamics. "The anti-icing tricks of penguins." ScienceDaily. ScienceDaily, 23 November 2015. <www.sciencedaily.com/releases/2015/11/151123103844.htm>.

 

 

Ice Loss Benefits Adélie Penguins—For Now

New research that may presage effects of climate change on this species looks back 22,000 years, finding robust growth in the East Antarctic population as melting followed the last ice age.

Over the past 14,000 years, Adélie penguin numbers in East Antarctica increased 135-fold because of disappearing glaciers and sea ice. The red staining is a mixture of mud and bird guano. Credit: Louise Emmerson

By Cody Sullivan 19 November 2015
 

Antarctic glaciers and sea ice may shrink as global temperatures rise, but Adélie penguins can thrive in a less icy Antarctic landscape, a new study indicates. By determining probable population levels of the birds as far back as 22,000 years ago, the research has revealed that the numbers of East Antarctic Adélie penguins swelled in the past 14,000 years.

The birds’ abundance grew pretty much in reverse proportion to the decline of Antarctic glacial and sea ice as the Earth thawed from its last ice age. Adélie penguins live along much of Antarctica’s coast, but over the past 14,000 years, the East Antarctic population increased 135-fold, reports Jane Younger, who was at the University of Tasmania, Australia, at the time of the study, and her colleagues. The team published its findings yesterday in BMC Evolutionary Biology.

Less Ice Means More Penguins

Adélie penguins need three environmental conditions to flourish: “They need ice-free terrain for their nests, they need open water access to their beaches, and they need a consistent food supply so they can forage and return to their colonies,” said Steven Emslie, an ornithologist from the University of North Carolina, Wilmington, who was not involved in this study. East Antarctica met those conditions as glacial ice retreated inland and sea ice melted from penguin foraging grounds. But regional variability meant that Adélie penguins in other parts of Antarctica didn’t benefit from climate change in the same way.

The many-fold increase in Adélie penguin numbers in East Antarctica isn’t constrained to the past few decades when humans ramped up their rate of forcing greenhouse gases into the atmosphere. The researchers used mitochondrial DNA from 56 living penguins to retrace the birds’ demographic history for the past 22,000 years. They determined that up until about 15,000 years ago, there were fewer than 1000 East Antarctic Adélie penguins. However, as conditions improved for the penguins there, other penguins from the Scotia Arc may have migrated over and bolstered the East Antarctic population. After that, the Adélie penguin population on East Antarctica increased in line with a general deglaciation trend as the Earth emerged around that same time from its last global glaciation.
In the past 30 years, as climate change ramped up and conditions continued to improve for the penguins, the Adélie population nearly doubled. Scientists estimate the current Adélie population at around 1.14 million breeding pairs, with 30% of them coming from the East Antarctic region.

Continued Growth Is Unclear

Even though the East Antarctic Adélie penguin population has grown abundantly, that doesn’t necessarily mean the population will continue to do so. Scientists don’t know how the penguin’s prey, Antarctic krill, will react to warming temperatures, and the temperatures might become too warm for the penguins themselves. “The warming trend does reach a threshold where it can be beneficial at first but then start having negative impacts,” said Emslie, who has already seen negative effects on Adélie penguins in his own research along the Antarctic Peninsula. The new study provides rare insight into how an animal population reacts to climate change on a millennial time scale, in contrast to a more recent decadal scale. “I think it’s important to realize that the climate change that’s happening now is not a short-term kind of thing. It’s a real change in the climate that’s going to last thousands of years,” said Younger, the study’s lead author, who is now at Loyola University in Chicago, Ill.

 

“If we want to really think about the effects of climate change on these animals, we need to think about not just how they’re going to be affected in the short term, but how they’re going to be affected in the long term as well. And that’s where these millennial-scale studies into the past can help.” —Cody Sullivan, Writer Intern

Citation: Sullivan, C. (2015), Ice loss benefits Adélie penguins—For now, Eos, 96, doi:10.1029/2015EO040059. Published on 19 November 2015.

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Shrinking Antarctic glaciers could make Adélie penguins unlikely winners of climate change

November 17, 2015 

 

 

Adélie Penguins struggle to reach their nesting sites if there’s too much ice in the way. Jane Younger, Author provided

Author: Jane Younger

Postdoctoral research fellow, University of Tasmania

Disclosure statement

Jane Younger receives funding from the Australian Antarctic Division, the ANZ Trustees Holsworth Wildlife Research Endowment, the Sea World Research and Rescue Foundation, and the National Science Foundation.

Partners

University of Tasmania provides funding as a member of The Conversation AU.

Penguin numbers exploded in East Antarctica at the end of the last ice age, according to research published today in BMC Evolutionary Biology. Despite their image as cold-loving creatures, the increase in Adélie penguin numbers seems to be closely linked to shrinking glaciers, raising the possibility the these penguins could be winners from current climate change.

Adélie penguins are one of only two penguin species that live on the Antarctic continent. Their cousins, emperor penguins, may be the movie stars, but it is the Adélies that are the bigger players in the Southern Ocean. They outnumber emperors by more than ten to one, with a population of over 7.5 million breeding adults and counting.

Given the abundance of Adélie penguins and their crucial role in Southern Ocean ecosystems, there has been a great deal of interest in understanding how the species is likely to respond to future climate change.

There are more then 7 million of these guys in Antarctica. Jane Younger, Author provided

Sensitivity to sea ice

Breeding colonies have been monitored for decades to determine the effects of a changing environment on the penguins. A common finding of many of these studies is that Adélies are highly sensitive to sea ice conditions.

Unlike emperor penguins, Adélies do not nest on the sea ice, but they must cross it to reach their nests on land. As everyone knows, penguins are not the most efficient walkers, and in years with a lot of sea ice their journeys to and from the ocean to feed their chicks can become lengthy. With a longer wait between meals chicks are less likely to survive.

In an extreme case, extensive sea ice at one breeding colony had a devastating impact in 2014, and not a single chick survived.

Based on these observations over years and decades, there has been concern that changing sea ice conditions, including increases in certain parts of Antarctica, could have a serious impact on Adélie penguin numbers in the future.

Short-term vs long-term climate change

However, the climate change that is taking place now is not a decadal trend. Rather, the shrinking glaciers and ice sheets, changing sea ice conditions, and shifting currents and weather patterns represent a global change to a new climate.

We therefore set out to understand how Adélie penguins in East Antarctica were affected by the last big shift to a different climate: the ending of the last ice age.

Following similar methods to our previous study on emperor penguins, we used genetic data to uncover the trend of the Adélie population in East Antarctica over the past 22,000 years.

Researchers have been investigating penguins to see how they might respond to climate change. Laura Morrissey, Author provided

The end of the ice age

We found that, as for the emperor penguins, Adélies were far less common during the ice age. This is not at all surprising since most of their nesting sites would have been covered with glaciers and their feeding grounds encased in sea ice that never melted.

Following the end of the ice age 20,000 years ago, temperatures increased slowly, and after a few thousand years of warming the glaciers and ice sheets began to shrink. Fast forward to 10,000 years ago and the annual sea ice melting cycle that we see today was established.

Given the sensitivity of Adélie penguins to sea ice changes today, we predicted that Adélie numbers would remain very small until 10,000 years ago when sea ice conditions became similar to what they are now.

However, the penguins surprised us again. We found that the number of Adélies exploded by around 135-fold, but the expansion pre-dated the sea ice change by at least 3000 years.

Penguin numbers exploded at the end of the last ice age. Jane Younger, Author provided

Shrinking glaciers

The proliferation of Adélie penguins in East Antarctica began during a period of ice sheet and glacier retreat, which would have increased the amount of ice-free ground available for nesting.

A study of Adélie penguins at the Scotia Arc, on the opposite side of the continent, found that numbers in this region rose 17,000 years ago. That expansion was several thousand years before the growth of the East Antarctic population, but coincided with the shrinking of glaciers in the Scotia Arc. This lends further support to our conclusion that it was glacier retreat, rather than changing sea ice conditions, that caused the hike in Adélie penguin numbers after the last ice age.

This is an important finding, as it suggests that the effects of climate change on a species over thousands of years can be quite different to the effects over years or decades. Given the long-term nature of contemporary climate change, we suggest that it is critical to consider millennial-scale trends alongside decadal ecological studies when predicting the effects of climate change on a species.

Could penguins benefit from future climate change?

Glaciers and ice sheets in Antarctica will continue to shrink. As this happens, ground that was previously covered in ice will become suitable for Adélie penguin nesting. In regions with adequate food supplies and where sea ice conditions remain favourable, Adélie penguin numbers may continue to grow.

A recent study using satellite images showed that one breeding colony in the Ross Sea grew by 84% between 1983 and 2010, as a direct result of a glacier shrinking by 543 m and uncovering new nesting sites.

While it seems that East Antarctic Adélie penguins might come out on top as climate change winners, it is important to keep in mind that for penguins to flourish their food supplies must be plentiful enough to meet the demands of a growing population. Whether this will be the case in the future remains to be seen, as Adélie penguin prey species, such as Antarctic krill, are threatened by both climate change and commercial fisheries.

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The dinosaur ankle re-evolved amphibian-like development in birds

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Date:

November 13, 2015

Source:

Universidad de Chile

Summary:

In the 19th century, Darwin's most vocal scientific advocate was Thomas Henry Huxley, who is also remembered as a pioneer of the hypotheses that birds are living dinosaurs. He noticed several similarities of the skeleton of living birds and extinct dinosaurs, among them, a pointed portion of the anklebone projecting upwards onto the shank bone (aka drumstick). This "ascending process" is well known to specialists as a unique trait of dinosaurs. However, until the late 20th century, many scientists were doubtful about the dinosaur-bird link. Some pointed out that the ascending process in most birds was a projection of the neighbouring heel bone, rather than the anklebone. If so, it would not be comparable, and would not support the dinosaur-bird link. 

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Like modern amphibians, the remote ancestors of birds once had three bones in their upper ankle. When these evolved into landegg-laying animals, only two bones were present in this region. In dinosaurs, one of these, the anklebone, presents a pointed upward projection, the "ascending process". This trait is also present in birds, which are living dinosaurs. A new detailed embryological study in birds reveals that their ankle has re-evolved an amphibian-like developmental pattern, with three separate elements, one of which becomes the dinosaurian ascending process

Credit: Image courtesy of Universidad de Chile

 

In the 19th century, Darwin's most vocal scientific advocate was Thomas Henry Huxley, who is also remembered as a pioneer of the hypotheses that birds are living dinosaurs. He noticed several similarities of the skeleton of living birds and extinct dinosaurs, among them, a pointed portion of the anklebone projecting upwards onto the shank bone (aka drumstick). This "ascending process" is well known to specialists as a unique trait of dinosaurs. However, until the late 20th century, many scientists were doubtful about the dinosaur-bird link. Some pointed out that the ascending process in most birds was a projection of the neighbouring heel bone, rather than the anklebone. If so, it would not be comparable, and would not support the dinosaur-bird link.

Some argued that in bird embryos, the ascending process develops from the anklebone in dinosaur-like fashion, while others considered that its development in birds is unique and different from dinosaurs. Nowadays, the dinosaur-bird link is mainstream science, thanks to new methods of data analysis, and a dense series of intermediate fossils (including feathered dinosaurs). However, the disagreements about the composition and embryology of the avian ankle were never clarified fully. A new study in Nature Communications by Luis Ossa, Jorge Mpodozis and Alexander Vargas, from the University of Chile, provides a careful re-examination of ankle development in 6 different major groups of birds, selected specifically to clarify conditions in their last common ancestor. It also utilizes new techniques that allow three-dimensional analysis of fluorescent embryonic skeletons, using advanced spin-disc confocal microscopy and software.

This work has revealed that the ascending process does not develop from either the heel bone or the ankle bone, but from a third element, the intermedium. In the ancient lineage of paleognath birds (such as tinamous, ostriches and kiwis) the intermedium comes closer to the anklebone, producing a dinosaur-like pattern. However, in the other major avian branch (neognaths), which includes most species of living birds, it comes closer to the heel bone; that creates the impression it is a different structure, when it is actually the same. "It puts the final nail in the anti-dinosaur coffin" says Jacques Gauthier, a vertebrate paleontologist and professor at Yale University "The dinosaurian ascending process is retained in all birds, though it has changed its association from ankle to heel bones in neognath birds."

More remarkably, however, this finding reveals an unexpected evolutionary transformation in birds. In embryos of the landegg-laying animals, the amniotes (which include crocodilians, lizards, turtles, and mammals, who secondarily evolved live birth) the intermedium fuses to the anklebone shortly after it forms, disappearing as a separate element. This does not occur in the bird ankle, which develops more like their very distant relatives that still lay their eggs in water, the amphibians. Since birds clearly belong within landegg-laying animals, their ankles have somehow resurrected a long-lost developmental pathway, still retained in the amphibians of today -- a surprising case of evolutionary reversal. The study also presented fossil evidence from juvenile specimens of toothed birds from the Cretaceous period. These show that, at this early stage of bird evolution, the ascending process already developed separately.

Evolutionary reversions have always generated much discussion among scientists, because ancient traits can occasionally re-appear in a highly transformed context. A recent paper in BMC Evolutionary Biology (Diaz and Trainor, 2015) has revealed that chameleons also re-evolved an independent intermedium, in the specialized functional context of a climbing reptile. The reappearance of this long-lost developmental pattern in highly evolved organisms like birds and chameleons could be compared to finding primitive clockwork gears inside your latest smartphone. These intriguing discoveries are bound to renew discussion about the interplay between the evolution of new functions and the resurrection of old developmental patterns.

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Story Source:
The above post is reprinted from materials provided by Universidad de Chile. Note: Materials may be edited for content and length.

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Journal Reference:

1. Luis Ossa-Fuentes, Jorge Mpodozis, Alexander O Vargas. Bird embryos uncover homology and evolution of the dinosaur ankle. Nature Communications, 2015; 6: 8902 DOI: 10.1038/ncomms9902

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Universidad de Chile. "The dinosaur ankle re-evolved amphibian-like development in birds." ScienceDaily. ScienceDaily, 13 November 2015. <www.sciencedaily.com/releases/2015/11/151113105924.htm>.

Flying under the radar: Seabirds hold the key to healthy fisheries

Seabirds are being severely threatened by fisheries, pollution and invasive species. Scientist and conservationalist Ross Wanless explains to DW why the birds of the sea could be pivotal for survival of the planet.

The African-Eurasian Waterbird Agreement (AEWA) met in Bonn, Germany, November 9 through 13 to discuss conservation of seabirds. In addition to aiming for an agreement from AEWA member countries on changing fishery management to benefit migratory seabirds, researchers and conservationists also worked together on managing other seabird threats.

DW caught up with Ross Wanless of BirdLife International toward the end of the conference in Bonn.

DW: What is the state of seabirds globally?

Ross Wanless: Seabirds are among the most threatened group of birds in the world, in fact their conservation status has decreased faster than any equivalent group of birds, so they are really not in good shape.

What is the biggest threat to seabirds?

There are two main threats, one is fisheries and a whole range of things within that - so accidental mortality and overfishing - and the other is invasive species on islands.

About 30 years ago, people discovered that when they counted up the number of birds that had been caught up in tuna longline fishing hooks and extrapolated that to the whole fishery, they realized that one or two birds on each boat every day translated into tens of thousands of albatrosses. That broke open a huge issue that we have been battling with ever since: how to stop birds from being caught on longlines.

Solving the problems of seabird conservation, Wanless says, is not an easy job

What, if any, solution exists to address the impact of fisheries on sea birds?

There are many solutions, some of them are quite simple and straightforward, don't cost a lot and allow fishing to continue really essentially unchanged. Like just minor modifications to their gear, or how fishers work.

There are other, probably more problematic solutions, such as reduction in fishing and area closures to fishing. There is a whole suite of things that can be done.

If we focus on your home country, South Africa, what would you say is needed there to help seabirds?

BirdLife South Africa has done some amazing work in preventing bycatch, or the incidental catching of seabirds in our fisheries, and our fisheries are some of the best in the world in terms of having solved these enormous problems almost completely.

But, we're really grappling with the problem of the lack of food and the role that fisheries play in causing the collapse of, for example, African penguin populations. So, while we have been good at solving some problems, we are still really coming to grips with some of the other problems.

Through your work, you have initiated some large-scale conservation programs to help the African penguin and other seabirds at risk of low trophic level fisheries impacts, what has that entailed?

Low trophic level fisheries, or forage fisheries, are fisheries that target the small things in the sea, like krill, or sardine or anchovy. They tend to be at the base of the ecosystem, the base of the food chain, so if you overfish those stocks, everything else that feeds on them - the whales, the dolphins, the seals, the seabirds, the other fish that are also commercially exploited - all take strain. It's a real problem and that's the kind of fishing we have to manage very carefully, and that is what we think is behind some of the African penguin collapse.

We need to look at seabirds to understand how other marine life are faring, says Wanless

There is no question that overfishing happened in our waters in the 1960s. The stocks of fish have changed dramatically, and the penguin numbers collapsed along with that.

How can people live harmoniously with seabirds? 

I think to many people, there is a false dichotomy. It's not seabirds or fisheries - actually, fisheries should be using seabirds. We believe that penguins, for example in the southwestern part of Africa, are a real sentinel: They are a signal that the marine system is under stress and that if we don't pay attention, the fisheries could collapse.

What we are trying to convince people is: Use the penguins, the information they are telling you is valuable, and you should maybe think seriously about changing your fishing practices.
Pitting penguins or other seabirds against fisheries is really the wrong way to look at it. When the penguins recover, you will probably have a healthy ecosystem again.

I challenge you to answer the question "how many fish are in the sea" with any degree of accuracy - but I can tell you exactly how many penguins there are in southern Africa. We have really good data that we can use, and if we could just change our mindset about that, I think everyone would be in a better space.

The average person may possibly say "seabirds don't concern me" - why should we care about them? 

Seabirds in many respects are an important tool for helping manage our impact on the marine environment. The interconnectedness of the ocean is dynamic and different from terrestrial environments, and we don't really have a good understanding or ability to mange it. If we let the seabirds go, if we forget about them and say we don't care, we can live without them - maybe we are right, maybe we are wrong. If we are wrong, have we lost something we can never recover, and everyone suffers at the end of the day? We are playing a high-risk game by ignoring critical components of ecosystems such as seabirds.

If we destroy those species, future generations will never forgive us - we have a responsibility to look after those things.

Fishers, government and individuals need to work together to ensure seabird survival, Wanless tells DW

What recent developments have been made to protect seabirds? 

Seabirds are probably the most international birds of all birds, because the high seas occupy about 60 percent of the surface of the Earth. No one owns the high seas, so they are not in any one country's waters for much of their lives. So we have to be joined up and work collaboratively to protect them.
We have created the World Seabird Union, which brings together 90 percent of seabird

conversationalists and researchers, and that gives us a united voice where we can discuss and plan around issues and hold conferences. This allows us to pull things together in a joint way that is so much more powerful than people or countries working individually.

What has come out of the Bonn conference?

The conference has really shown the willingness of countries to grapple with issues and to find effective, efficient ways of addressing problems - not duplicating existing initiatives or existing programs - and that is really encouraging.

That means we are not throwing money at problems. Everyone is really conscious of finding ways where an agreement can be used to do things that no one else is doing, and we don't need to bother with where others are doing them - that, to me, is a really encouraging sign.

Dr. Ross Wanless is the Africa Coordinator for the BirdLife International Marine Programme, and the Seabird Conservation Programme manager for BirdLife South Africa.

The interview was conducted by Jessie Wingard.

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Shape of bird wings depends on ancestors more than flight style

Date:

November 5, 2015

Source:

University of Texas at Austin

Summary:

In a finding that could change the way scientists think about bird evolution, researchers have found that the shape of bird wings is influenced more by how closely related species are to one another than by flight style.The research challenges scientific beliefs that assume the way a bird species flies -- whether it primarily dives, glides or flaps, for instance -- plays the primary role in the evolution of its wing shape.

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Samples of the dorsal (middle column) and ventral (left column) sides of wings from bird specimens analyzed by the researchers. The right column depicts a consensus wing shape generated by analyzing the wing shape of 105 bird taxon (figure f), a figure depicting how various wing shapes differed from the consensus wing (figure g), and the magnitude of variation across different parts of the consensus wing ( figure h). Credit: Xia Wang.

In a finding that could change the way scientists think about bird evolution, researchers have found that the shape of bird wings is influenced more by how closely related species are to one another than by flight style.

The research challenges scientific beliefs that assume the way a bird species flies--whether it primarily dives, glides or flaps, for instance--plays the primary role in the evolution of its wing shape. It also indicates that it may be more difficult than previously thought to infer flying behaviors of early birds and the first flying dinosaurs from fossils alone.

Julia Clarke, an associate professor in the Department of Geological Sciences at The University of Texas Jackson School of Geosciences, conducted the work with Xia Wang, a post-doctoral researcher who led the study. Their research was published in the journal Proceedings of the Royal Society B: Biological Sciences in October.

Bird wings, unlike stiff airplane wings, are flexible and change shape during flight. So, their geometry and wing outline may not tell the whole story of a particular flight style or environment, Clarke said. "We've taken a lot for granted. Birds are not airplanes," Clarke said.

By comparing geometry across species and clades -- groups of organisms that evolved from a common ancestor -- the researchers found that birds that are closely related evolutionarily have similar wing structures, even if the birds show very different flight styles. For example, albatrosses, penguins and loons, despite looking very different from one another, all belong to the clade Aequornithes and have a wing shape that is very similar.

The study is the first to analyze wing geometry across all major groups of birds. Researchers
analyzed over 100 photographs of wings from different bird species.

In general, the analysis of species from across nine major avian clades showed that wing shape became more varied as different clades diverged from early ancestors, Clarke said. The researchers found an interesting exception to this trend in the wings of Passerines --a clade that includes songbirds. Instead of a wing shape that resembles more closely related relatives, their shape resembles that of Galliformes, a distantly related order that includes birds, such as chickens and turkeys, whose direct ancestors were among the first birds on the planet. "Those little songbirds share aspects of wing geometry, especially the relative length of the covert feathers, with some of early bird species but have very different body sizes, ecologies and flight styles," Clarke said.

Clarke and Wang also studied covert feathers in these birds. They found that across clades these feathers, which cover the base of the flight feathers, are about the same length whether they are on the top or underside of a wing. The similarity of covert feathers both on a single wing and across clades, brings into question their function, Clarke said.

It's been proposed that some of the upper coverts may play a sensory role, and the lower or underwing coverts, a role in aerodynamics. But the similarity in the distribution and organization of covert feathers on both sides of the wings suggests that such distinct roles may not be the case, Clarke said. "There's no existing hypothesis to explain that pattern," Clarke said. "So a question now is why the length of these feathers tends to be similar and why they show similar trends across birds. We could be looking for a developmental explanation or a functional one."

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Story Source:
The above post is reprinted from materials provided by University of Texas at Austin. Note: Materials may be edited for content and length.

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Journal Reference:

1. Xia Wang, Julia A. Clarke. The evolution of avian wing shape and previously unrecognized trends in covert feathering. Proceedings of the Royal Society B: Biological Sciences, 2015; 282 (1816): 20151935 DOI: 10.1098/rspb.2015.1935

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University of Texas at Austin. "Shape of bird wings depends on ancestors more than flight style." ScienceDaily. ScienceDaily, 5 November 2015. <www.sciencedaily.com/releases/2015/11/151105103041.htm>.