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