Thursday, November 29, 2012

For Some Feathered Dinosaurs, Bigger Not Always Better


This scale illustration shows size of feathered theropod herbivores compared to humans. (Credit: Lindsay Zanno, NC State and NC Museum of Natural Sciences)
ScienceDaily (Nov. 27, 2012) — Every kid knows that giant carnivores like Tyrannosaurus rex dominated the Cretaceous period, but they weren't the only big guys in town. Giant plant-eating theropods -- close relatives of both T. rex and today's birds -- also lived and thrived alongside their meat-eating cousins. Now researchers have started looking at why dinosaurs that abandoned meat in favor of vegetarian diets got so big, and their results may call conventional wisdom about plant-eaters and body size into question.

Scientists have theorized that bigger was better when it came to plant eaters, because larger digestive tracts would allow dinosaurs to maximize the nutrition they could extract from high-fiber, low-calorie food. Therefore, natural selection may have favored increasing body sizes in groups of animals that went meatless.

Three groups of giant feathered theropods from the Cretaceous period seemed to follow that rule of thumb -- the biggest specimens were also the plant-eaters. Lindsay Zanno, research assistant professor of biology at North Carolina State University and director of the Paleontology & Geology Research Lab at the North Carolina Museum of Natural Sciences, and Peter Makovicky, associate curator of paleontology at the Field Museum in Chicago, decided to see if diet was the determining factor when it came to size. Makovicky notes that "Having three closely related lineages of dinosaurs adapting to herbivory over the same geological time span and showing evidence of increasing size provided a near perfect test case."

Zanno and Makovicky estimated body mass for 47 extinct species of feathered dinosaur, representing three major groups that abandoned a strictly meat-eating diet -- ornithomimosaurs ("bird-mimics"), oviraptorosaurs ("egg-thieves"), and the bizarre therizinosaurs ("scythe-lizards"). Most species in these lineages also possessed a toothless beak, three-toed feet, and shorter tails than your average dinosaur, making them look a lot like modern birds.

All three groups evolved gigantic proportions: the largest oviraptorosaur weighed over 7,000 pounds, and the biggest ornithomimosaurs and therizinosaurs topped out at over 13,000 pounds. "The largest feathered dinosaurs were more than 100 times more massive than your average person," says Zanno. "The reality is that for most of us, it is downright difficult to imagine a feathered animal of gigantic proportions."

The researchers also found that average body mass did increase in these groups over time (on average, the earliest members were smallest and the last species to evolve were among the largest). But this simple correlation didn't indicate whether large size was an evolutionary advantage.
To test whether these groups were being driven to get bigger by natural selection, Zanno and Makovicky fitted different evolutionary models to the data, looking to see which model best described the patterns of body mass from ancestor species to descendant species. They found that these theropod groups were experimenting with different body masses as they evolved, with some getting bigger, while others were getting smaller. In short, there was no clear-cut drive to get big -- size seemed to provide no overwhelming advantage during the evolution of these animals.
The researchers' results appear in Proceedings of the Royal Society B.

"Results of our study don't rule out diet as affecting body mass, but do seem to indicate that fluctuating environmental conditions over time were trumping the benefit of becoming a giant," Zanno says. "The long and short of it is that for plant-eating theropods, bigger wasn't always better."
"Where resources permitted, these animals could get as big as elephants, but that clearly was not the case in all environments and time periods," says Makovicky. "Factors such as resource abundance and competition with other herbivores likely played a more significant role." He added that uneven sampling in the fossil record, such as preferential preservation of smaller species in earlier time periods and larger species in later ones, could also impact the results.

Story Source:
The above story is reprinted from materials provided by North Carolina State University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. L. E. Zanno, P. J. Makovicky. No evidence for directional evolution of body mass in herbivorous theropod dinosaurs. Proceedings of the Royal Society B: Biological Sciences, 2012; 280 (1751): 20122526 DOI: 10.1098/rspb.2012.2526

North Carolina State University (2012, November 27). For some feathered dinosaurs, bigger not always better. ScienceDaily. Retrieved November 29, 2012, from­ /releases/2012/11/121128093254.htm

Thursday, November 22, 2012

New Evidence On Dinosaurs' Role in Evolution of Bird Flight

An artist’s impression of what the Archaeopteryx lithographica would have looked like in flight. (Credit: Image by artist Carl Buel)
ScienceDaily (Nov. 21, 2012) — A new study looking at the structure of feathers in bird-like dinosaurs has shed light on one of nature's most remarkable inventions -- how flight might have evolved.

Academics at the Universities of Bristol, Yale and Calgary have shown that prehistoric birds had a much more primitive version of the wings we see today, with rigid layers of feathers acting as simple airfoils for gliding.
Close examination of the earliest theropod dinosaurs suggests that feathers were initially developed for insulation, arranged in multiple layers to preserve heat, before their shape evolved for display and camouflage.

As evolution changed the configuration of the feathers, their important role in the aerodynamics and mechanics of flight became more apparent. Natural selection over millions of years ultimately modified dinosaurs' forelimbs into highly-efficient, feathered wings that could rapidly change its span, shape and area -- a key innovation that allowed dinosaurs to rule the skies.

This basic wing configuration has remained more or less the same for the past 130 million years, with bird wings having a layer of long, asymmetrical flight feathers with short covert feathers on top. They are able to separate and rotate these flight feathers to gain height, change direction and even hover.

This formation allows birds to move in such a way as to produce both lift and thrust simultaneously -- a capability that man, with the help of technology, is still trying to successfully imitate.

The research, published November 21 in Current Biology, looked at the dinosaur Anchiornis huxleyi and the Jurassic bird Archaeopteryx lithographica. The latter is 155 million years old and widely considered to be the earliest known bird, presenting a combination of dinosaur and bird characteristics.

Their wings differed from modern day birds in being composed of multiple layers of long feathers, appearing to represent early experiments in the evolution of the wing. Although individual feathers were relatively weak due to slender feather shafts, the layering of these wing feathers is likely to have produced a strong airfoil.

The inability to separate feathers suggests that taking off and flying at low speeds may have been limited, meaning that wings were primarily used in high-speed gliding or flapping flight.

Dr Jakob Vinther, from the University of Bristol's Schools of Biological and Earth Sciences, said: "We are starting to get an intricate picture of how feathers and birds evolved from within the dinosaurs. We now seem to see that feathers evolved initially for insulation. Later in evolution, more complex vaned or pinnate feathers evolved for display.

"These display feathers turned out to be excellent membranes that could have been utilised for aerial locomotion, which only very late in bird evolution became what we consider flapping flight. This new research is shedding light not just on how birds came to fly, but more specifically on how feathers came to be the way they are today -- one of the most amazing and highly specialised structures in nature."

Dr Nicholas Longrich of Yale University added: "By studying fossils carefully, we are now able to start piecing together how the wing evolved. Before, it seemed that we had more or less modern wings from the Jurassic onwards. Now it's clear that early birds were more primitive and represented transitional forms linking birds to dinosaurs. We can see the wing slowly becoming more advanced as we move from Anchiornis, to Archaeopteryx, to later birds."

Story Source:
The above story is reprinted from materials provided by University of Bristol.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. Nicholas R. Longrich, Jakob Vinther, Qingjin Meng, Quangguo Li, Anthony P. Russell. Primitive Wing Feather Arrangement in Archaeopteryx lithographica and Anchiornis huxleyi. Current Biology, 21 November 2012 DOI: 10.1016/j.cub.2012.09.052

University of Bristol (2012, November 21). New evidence on dinosaurs' role in evolution of bird flight. ScienceDaily. Retrieved November 22, 2012, from­ /releases/2012/11/121121130817.htm

Argentine experts from the Natural Sciences Museum of La Plata find giant penguin fossils in Antarctica

Previous finds from prehistoric penguins indicated they did not sport the iconic black and white 
feathers the birds are known for today, but had reddish-brown and gray plumage. Photo: Natural 
Sciences Museum of La Plata.

BUENOS AIRES (AFP).- Argentine experts have discovered the fossils of a two-meter (6.5 foot) tall 
penguin that lived in Antarctica 34 million years ago.

Paleontologists with the Natural Sciences Museum of La Plata province, where the capital Buenos 
Aires is located, said the remains were found on the icy southern continent.

"This is the largest penguin known to date in terms of height and body mass," said researcher Carolina 
Acosta, who noted that the record had been held by emperor penguins, which reach heights of 1.2 
meters (4 feet) tall.

Lead researcher Marcelo Reguero added that the find, announced Tuesday, will "allow for a more 
intensive and complex study of the ancestors of modern penguins."

In its next expedition to Antarctica, during the region's summer, the team will seek additional fossils 
of the newly discovered species, as well as information about its anatomy and how the giant penguin 
might have moved.

Previous finds from prehistoric penguins indicated they did not sport the iconic black and white 
feathers the birds are known for today, but had reddish-brown and gray plumage.


Wednesday, November 21, 2012

Emperor Penguins Need Sea Ice for Foraging

   Emperor penguins near the sea in Antarctica.
CREDIT: Katsufumi Sato, Atmosphere and Ocean Research Institute, The University of Tokyo

 (Click image for much larger view)

Becky Oskin, OurAmazingPlanet Staff Writer - Nov 21, 2012

Motion detectors mounted on emperor penguins have revealed that sea ice plays a critical role in the birds' long food odyssey.

Emperor penguins rely on sea ice for breeding and feeding. Shifting patterns of sea ice due to changing climate in the Antarctic could alter the penguin's behavior and ecology, said study author Shinichi Watanabe, an animal ecologist and professor at Fukuyama University in Hiroshima, Japan.
The Antarctic sea ice hit a record maximum this year, but the sea ice distribution around the continent is changing, while the penguins nest in the same place every year.

"If penguins don't stay on the ice during foraging trips, they may not be able to sustain such long trips," Watanabe told OurAmazingPlanet.

March to the sea

The image of thousands of penguins shuffling across the frigid Antarctic ice was immortalized in the film "March of the Penguins." Female emperor penguins trek 30 to 75 miles (50 to 120 kilometers) each way during chick-rearing season to bring back food for their young.

Emperor penguins spend more time foraging than any other penguin species, Watanabe said. "Emperor penguins are a unique ecology, because they are the largest species of penguins and they have the biggest and largest chicks, so they have to bring [a lot of] food," he said. "Also, the distance between the breeding colony and the foraging site is very long, so they need more food."

The ice helps the penguins gorge on food by providing short, safe rest breaks between long dives, Watanabe and his colleagues found. The results, based on 10 penguins from a colony at Cape Washington in the Ross Sea, were published online today (Nov. 21) in the journal PLoS Biology.

The relationship between sea ice conditions and emperor penguins' foraging has been unclear because of the difficulties of tracking the birds at sea, Watanabe said. To figure out how penguins behave once they reach the open ocean, the researchers used special probes that captured motion on land and underwater.

Safety in numbers

The first thing the animals do after their long walk is rest, the researchers found. After leaving the colony and arriving at the ice edge before the start of a foraging trip, the birds spent 3 hours to 38 hours waiting before making the first dive.

The researchers suspect that the long rests are a result of penguins waiting for others to form a group. Antarctic penguins prefer to dive in flocks, slipping into the water all at once from the ice edge. This could help lower the risk of a seal attack, as leopard seals eagerly await these group dives and there is safety in numbers. However, it's more likely that the phenomenon is simply a result of group behavior, the authors report in the study.

With 24 hours of sunlight, penguins dived continuously through day and night, spending up to two weeks foraging. They relied on the ice for rests between deep dives that lasted up to five hours (with quick breath breaks).



Saturday, November 17, 2012

Math Reveals Perfectly Cozy Penguin Huddles

Date: 16 November 2012
Penguins in a colony pack extremely tightly together, but still shuffle around without crushing anyone.
Penguins in a colony pack extremely tightly together, but still shuffle around without crushing anyone.
CREDIT: March of the Penguins (National Geographic film)

Greed is good for penguins that huddle together to avoid Antarctica's icy weather.
According to a new study, penguin groups can maximize everyone's heat when individual birds act selfishly, huddling in ways that keep them toastiest.

"Even if penguins are only selfish, only trying to find the best spot for themselves and not thinking about their community, there is still equality in the amount of time that each penguin spends exposed to the wind," study researcher Francois Blanchette, a mathematician at the University of California, Merced, who normally studies fluid dynamics, said in a statement.

Blanchette became interested in penguin huddles after watching the hit documentary "The March of the Penguins." He and his colleagues made mathematical models of penguin huddles, varying wind strength and turbulence to see what sort of shapes arose. The model calculated which penguin along the edge of the huddle would be coldest and had that penguin move toward the center of the huddle in a sort of constant rotation.

These models produced long, thin huddles that gradually crept away from the wind direction. In real life, penguin huddles are more rotund, so researchers went about making their models more realistic. They added an element of uncertainty, such as wind eddies and differences in size of the huddled penguins. The result was huddles that look much like those seen on real Antarctic ice.

"A penguin huddle is a self-sufficient system in which the animals rely on each other for shelter, and I think that is what makes it fair," Blanchette said. An obstacle to the ideal shape, such as a wall, would likely make the huddles less fair, he added.

Blanchette and his mathematician colleagues report their work today (Nov. 16) in the journal PLOS ONE, and will present the findings at the American Physical Society's fluid dynamic conference next week in San Diego. They hope to get feedback from biologists on their findings. The model may also help biologists refine their observations of penguins in the field by letting them know what behaviors to look for in huddles.

Blanchette also hopes the penguin study will help spread the word about his first love, math.
"Nearly everybody seems to love penguins, and not enough people love math," he said. "If we use math to study penguins, we could potentially teach more people to love math, too!"


Friday, November 16, 2012

Controversial Toronto Zoo Penguins Not Gay after All?

toronto zoo penguins What a difference a year makes. Last November, two male African penguins (Spheniscus demersus) living at the Toronto Zoo made worldwide headlines after they took more interest in each other than in members of the opposite sex.

Considering the penguins—Pedro and Buddy—were brought to the zoo for breeding purposes, it posed quite the conundrum for zookeepers who planned to separate the pair in hopes that attractive females would catch their eyes.

As I wrote last year, it wasn’t clear at the time if the penguins were truly homosexual or just lonely, but now we have an update. The planned separation, it seems, did the trick. Not only have Pedro and Buddy bonded with waiting females, they have gone ahead and mated. This week their mates laid six precious new eggs.

If the eggs hatch next month—which isn’t guaranteed—it will be an important success for the zoo’s effort to breed these endangered species (also known as black-footed penguins), which have experienced a 75 percent wild population drop over the past two decades. The zoo hatched three male penguins last year, all of which have survived.

This is actually Buddy’s second chance at fatherhood since last November. He and his mate Farai incubated and hatched two chicks in February, but neither survived. As the zoo wrote in a press release (pdf) at the time, “Mortality of chicks is high within the first three weeks after hatching with both wild and captive-bred penguins from any one of several factors such as predation, competition from other pairs, weather and the experience of the parents.”

Although Buddy and Pedro no longer act like a same-sex couple, two homosexual king penguins (Aptenodytes patagonicus) in Denmark’s Odense Zoo recently became parents after several years of cohabitation. A female penguin abandoned her egg and the two males stepped in to save it.
Zookeepers had previously noticed the males’ desire to be parents when the birds tried incubating dead herring and then tested their skills with a ball before a real egg became available. The birds took turns incubating the egg, which hatched last month. By all accounts, the chick is doing well.

Homosexuality in penguins has been observed in the wild, notably in king penguins. A 2010 study of the species found instances of males flirting with one another and male–male or female–female bonded pairs, although many broke up if more suitable opposite-sex mates turned up. A 2009 study published in Trends in Ecology & Evolution found that some species adapt to same-sex bonding in order to create more parenting roles. Homosexuality has been observed in more than 1,000 species.

Photo: African penguins at Toronto Zoo by Erica Peterson via Flickr. Used under Creative Commons license


Friday, November 9, 2012

Two New Emperor Penguin Colonies in Antarctica

The first emperor penguin colony. (Credit: © Robin Cristofari/CNRS/Institut polaire français IPEV)

ScienceDaily (Nov. 8, 2012) — While about 2500 chicks of emperor penguins are raised this year at the colony close to the French Dumont d'Urville Station, two new colonies totalling 6000 chicks have just been observed about 250 km away, near Mertz Glacier by the scientists Dr André Ancel and Dr Yvon Ancel, from the Institut Pluridisciplinaire Hubert Curien in Strasbourg (CNRS and Université de Strasbourg). Since a pair of emperor penguins may only successfully raise one chick a year, the population of breeding emperor penguins in this area of the Antarctic can therefore be estimated to more than about 8500 pairs, about three fold that previously thought.

The two new colonies have been revealed on 1st and 2nd November, during the late winter season trip of the MSS Astrolabe1 towards Dumont d'Urville. They are located on the winter sea ice. This ice surrounds the remains of the Mertz Glacier, from which a large ice wall, 80 km long, 40 km wide and 300-400 m thick has separated. These may be two sub-populations originating from the initial Mertz colony which, following the Mertz Glacier break, are attempting to settle again on favorable surroundings. One accounts for about 2000 chicks and the second for about 4000 chicks.

Dr André Ancel had suspected the existence of an emperor penguin colony near the Mertz Glacier since 1999, when with Dr Barbara Wienecke (Australian Antarctic Division), they observed thousands of emperor penguins going back and forth in the Mertz glacier area. Dr Peter Fretwell and Dr Phil Trathan of the British Antarctic Survey localised this colony in 2009 based on the images from space of emperor penguin nitrogen dejections on the sea ice. However, the break of the Mertz glacier in 2010 questioned the fate of this colony. New satellite images obtained since then suggested that the birds might attempt breeding on different sites. Over the last 13 years all French attempts to find the birds had failed, due to the harsh winter conditions and the summer disappearance of the sea ice where the Emperors breed.

This year, the human, logistic and environmental conditions finally came together. The French Polar Institute (IPEV) then decided to modify the Astrolabe's route to enable Dr André Ancel and Dr Yvon Le Maho to find this population. A good climate window, the excellent knowledge of the environment by the IPEV logistic teams, the expert navigational skill of the Astrolabe crew in the ice and the essential helicopter support in such areas, have allowed for the success of this detection. The break of the Mertz Glacier had profoundly modified the environment into a chaos of small icebergs and sea ice. The French scientists discovered that the initial colony seen from space by their British colleagues had been split over two sites. The first, whose localisation had been recently indicated by the British, accounts for about 2000 chicks, whereas 4000 are being raised in the second. The second site was discovered by chance, 15 km from the first, while conducting a scientific helicopter survey.

Story Source:
The above story is reprinted from materials provided by Centre national de la recherche scientifique (CNRS).
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Centre national de la recherche scientifique (CNRS) (2012, November 8). Two new emperor penguin colonies in Antarctica. ScienceDaily. Retrieved November 9, 2012, from­ /releases/2012/11/121108181439.htm

Thursday, November 1, 2012

The fight is not over for the Southern Ocean!

Today is a sad day for the Southern Ocean. CCAMLR’s (Commission for the Conservation of Antarctic Marine Living Resources) commitment to the global community to create large-scale marine reserves in the Southern Ocean was dishonoured today. We are deeply disappointed.

But rest assured the fight is not over. For the second time in thirty years, CCAMLR has agreed to hold a “special extraordinary” meeting in July to focus on reaching agreement on marine protection areas (MPAs) in the Southern Ocean. This special meeting would not have happened without your support. Failure will not be an option at the next meeting. We know that you and the rest of the world will be watching, and taking action.

We want to thank you for all of your support this year. Your effort is going to be critical to success in 2013. We will be back on board with plans bigger and better than ever to protect the Southern Ocean next week.

Stay tuned we will be right back!


© Antarctic Ocean Alliance 2011 |
Steve Campbell

(AOA Campagin Director) and the rest of the AOA team.
The AOA Team

Exhaustive Family Tree for Birds Shows Recent, Rapid Diversification

Analysis of the family tree shows when and where birds diversified — and that birds’ diversification rate has increased over the last 50 million years, challenging the conventional wisdom of biodiversity experts. (Credit: Image courtesy of Yale University.

ScienceDaily (Oct. 31, 2012) — A Yale-led scientific team has produced the most comprehensive family tree for birds to date, connecting all living bird species -- nearly 10,000 in total -- and revealing surprising new details about their evolutionary history and its geographic context.

Analysis of the family tree shows when and where birds diversified -- and that birds' diversification rate has increased over the last 50 million years, challenging the conventional wisdom of biodiversity experts.

"It's the first time that we have -- for such a large group of species and with such a high degree of confidence -- the full global picture of diversification in time and space," said biologist Walter Jetz of Yale, lead author of the team's research paper, published Oct. 31 online in the journal Nature.
He continued: "The research highlights how heterogeneously fast diversifying species groups are distributed throughout the family tree and over geographic space. Many parts of the globe have seen a variety of species groups diversify rapidly and recently. All this leads to a diversification rate in birds that has been increasing over the past 50 million years."

The researchers relied heavily on fossil and DNA data, combining them with geographical information to produce the exhaustive family tree, which includes 9,993 species known to be alive now.

"The current zeitgeist in biodiversity science is that the world can fill up quickly," says biologist and co-author Arne Mooers of Simon Fraser University in Canada. "A new distinctive group, like bumblebees or tunafish, first evolves, and, if conditions are right, it quickly radiates to produce a large number of species. These species fill up all the available niches, and then there is nowhere to go. Extinction catches up, and things begin to slow down or stall. For birds the pattern is the opposite: Speciation is actually speeding up, not slowing down."

The researchers attribute the growing rate of avian diversity to an abundance of group-specific adaptations. They hypothesize that the evolution of physical or behavioral innovations in certain groups, combined with the opening of new habitats, has enabled repeated bursts of diversification. Another likely factor has been birds' exceptional mobility, researchers said, which time and again has allowed them to colonize new regions and exploit novel ecological opportunities.

In their analysis, the researchers also expose significant geographic differences in diversification rates. They are higher in the Western Hemisphere than in the Eastern, and higher on islands than mainlands. But surprisingly, they said, there is little difference in rates between the tropics and high latitudes. Regions of especially intense recent diversification include northern North American and Eurasia and southern South America.

"This was one of the big surprises," Jetz said. "For a long time biologists have thought that the vast diversity of tropical species must at least partly be due to greater rates of net species production there. For birds we find no support for this, and groups with fast and slow diversification appear to occur there as much as in the high latitudes. Instead, the answer may lie in the tropics' older age, leading to a greater accumulation of species over time. Global phylogenies like ours will allow further tests of this and other basic hypotheses about life on Earth."

Other authors are G.H. Thomas of the University of Bristol in the United Kingdom; J.B. Joy of Simon Fraser University in Canada; and K. Hartmann of the University of Tasmania in Australia.
The work was supported by the National Science Foundation, NASA, the Natural Environment Research Council (U.K), the Natural Sciences and Engineering Research Council of Canada, Simon Fraser University, and the Yale Institute of Biospheric Studies.

Story Source:
The above story is reprinted from materials provided by Yale University.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:
  1. W. Jetz, Thomas, G. H., Joy, J.B., Hartmann, K. & A.O. Mooers. The global diversity of birds in space and time. Nature, October 31, 2012

Yale University (2012, October 31). Exhaustive family tree for birds shows recent, rapid diversification. ScienceDaily. Retrieved November 1, 2012, from­ /releases/2012/10/121031141906.htm