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Posts Tagged ‘Animals’

Trove of Dinosaur Feathers Found in Canadian Amber

15 Sep
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Discovery

An extraordinary collection of ancient feather fragments preserved in amber has opened a window into a lost world, one that now appears populated by dinosaurs covered in plumage as rich and varied as that of modern birds.

The feathers date to the end of the Cretaceous, about 85 to 70 million years ago. At that time, the forerunners of birds were well on their way to taking wing; dinosaurs like Epidexipteryx and Limosaurus, discovered in China in the last decade and dating to approximately 160 million years ago, possess relatively bird-like bone structures and hints of what might have been feathers.

Those hints have been interpreted -- and given life in eye-popping artist renditions -- as feathers, an interpretation that was plausible but still inconclusive.

But the latest fossils, found in Alberta and described Sept. 16 in Science, leave little doubt. The age of dinosaurs was a feathery one.

"These lovely specimens of significantly older, smaller dinosaurs from China have got some sort of covering about them. But you can't tell if it's hair or feathers because the fossils have undergone the ravages of time," said paleontologist Alex Wolfe of the University of Alberta, a co-author of the new study. "Those fossils don't preserve the kind of detail that we have in amber, which doesn't fossilize but entombs an object."

On the following pages, Wired.com looks at the new trove of feathers.

Above:

Feathers in Amber

Image: McKellar et al./Science

<< Previous | Next >>

See Also:

Citations: “A Diverse Assemblage of Late Cretaceous Dinosaur and Bird Feathers from Canadian Amber.” By Ryan C. McKellar, Brian D. E. Chatterton, Alexander P. Wolfe, Philip J. Currie. Science, Vol. 333 Issue 6049, September 16, 2011.

“Fossilized Feathers.” By Mark A. Norell. Science, Vol. 333 Issue 6049, September 16, 2011.

 
 

Bird Flight Might Have Started With Legs, Not Wings

18 Aug

To take flight, first strengthen your legs: It sounds like a self-help proverb, but it could explain how birds first took wing.

Until now, most explanations of the evolution of flight have assumed that going airborne was an end in itself, driven by the need of some early dinosaur to glide down from trees or up off the ground.

But flight could have instead been an incidental benefit of beefier muscles needed to compensate for losing a heat-generating protein.

“Flight is seen as the hallmark of bird evolution,” said developmental biologist Stuart Newman of the New York Medical College. “But you can make the argument that the particular form bird skeletons took that opened the way for flight was a side effect.”

Newman’s research shows that all birds and reptiles lack a single gene that codes for a protein called UCP1 or, with a nod to its function, thermogenin. It’s an essential part of the metabolic reaction that burns brown fat, helping bodies self-regulate internal temperature and generate heat without shivering.

Thermogenin’s absence from birds and reptiles hints at its loss in some early common ancestor, with the thermogenin-retaining relative later giving rise to mammals. But whereas reptiles became cold-blooded, basking in sunshine when needed, birds stayed warm-blooded.

Image: Markiza/Flickr

As Newman describes in a September Bioessays paper, the key to their warmth is muscles. Muscles are powerful generators of heat, which is a byproduct of the chemical reaction that makes them contract. Bird muscles also have further heat-generating adaptations. And birds are, in a word, jacked.

In ounce-for-ounce comparison, mammals and reptiles are scrawny weaklings next to birds. And it’s not just avian breast muscles that are pumped, as would be expected in flyers, but their legs too.

“My hypothesis is that birds basically salvaged their existence by developing very large skeletal muscles,” said Newman.

Once heavily muscled, he believes proto-birds would naturally have gravitated towards bipedalism, which isn’t a particularly challenging transition. Indeed, walking on two legs was widespread in dinosaurs.

Bipedality releases upper limbs, both literally and in evolutionary terms, allowing them to accumulate large mutations with relatively little risk. Combine that with powerful breast muscles, and wings would soon follow.

Testing Newman’s hypothesis may not be possible, as it would require comparing early bird and dinosaur skeletons and genes, and DNA is lost in the fossil record. But that flight could plausibly have been a fortunate side effect of some unrelated adaptation, rather than the original driver of bird development, is a useful evolutionary lesson.

Newman also suggests people at least reconsider the phenomenon of flightlessness in birds, which is generally portrayed in terms of loss.

“It’s almost universally accepted that all flightless birds come from flighted ancestors,” said Newman. “That might be true — but maybe it’s flying birds that have flightless ancestors. Maybe flightless birds were the leading edge.”

Top image: Lip Kee Yap/Flickr

See Also:

Citation:”Thermogenesis, muscle hyperplasia, and the origin of birds.” By Stuart Newman. Bioessays, Vol. 33 No. 9, September 2011.

 
 

Cross-Species Gadget Tests Reveal Reason for Dolphin Tools

25 Jul

The dolphins of Australia’s Shark Bay, famed as Earth’s first marine tool-users, likely turned to gadgetry because echolocation couldn’t find the best fish, especially for hurried moms without time to hunt.

It was in 1984 that researchers first observed the dolphins fitting basket sponges over their beaks, then scraping through seafloor mud to disturb hidden fish. Research subsequently showed this behavior to be full-blown tool use, taught by mothers to their daughters and representing a profound difference in lifestyle between them and Shark Bay’s other bottlenoses.

A basic question remained unanswered, however: Though sponges clearly protected sensitive dolphin snouts from jagged pieces of rock and coral, why scrape seafloor at all? Why not rely on echolocation to pinpoint target prey?

In a study published July 20 in Public Library of Science ONE, biologists Eric Patterson and Janet Mann of Georgetown University set out to answer this question by mounting basket sponges on sticks and pushing them through Shark Bay seafloors, just as dolphins do.

Most fish scared from the muck were bottom-dwellers lacking swim bladders, the air-filled organs that help fish control their buoyancy. Compared to fish flesh, which interferes with acoustic signals just slightly more than water, air bladders stand out on sonar. Without them, bottom-dwelling fish are nearly invisible to echolocation. Hence the value of scraping through seafloors manually, and thus the need for a device that protects dolphin noses from scraping.

Hunting with sponges has allowed Shark Bay’s bottlenoses to fill an empty ecological niche, eating fish that other dolphins ignore, wrote Patterson and Mann. The findings also suggest why sponge foraging likely arose among Shark Bay’s females and has remained their province, taught by dolphin mothers to daughters rather than sons.

Whereas dolphin fathers are mostly absent, free to roam and chase prey in the open ocean, dolphin moms spend years with their calves. They need to put food on the figurative table but have little time to do it. Sponge foraging is convenient and nutritious, a family recipe for quick-but-delicious dinners passed on to daughters who will someday need it.

Image: Eric Patterson/PLoS ONE

See Also:

Citation: “The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.). By Eric Patterson & Janet Mann. PLoS ONE, July 20, 2011.

 
 

Lost Rainbow Toad Found After 87 Years

14 Jul

By Mark Brown, Wired UK

Herpetologists at Conservation International have rediscovered the exotic Sambas stream toad (aka Borneo rainbow toad, aka Ansonia latidisca) after 87 years of evasion, and released the first ever photographs of the brightly colored amphibian.

The spindly-legged species was last seen in 1924 and European explorers in Borneo only made monochrome illustrations of it. A decade or so later, the CI and the SSC Amphibian Specialist Group added the species to its World’s Top 10 Most Wanted Lost Frogs campaign.

Indraneil Das of Universiti Malaysia Sarawak decided to hunt down the lost frog, and his team looked in the nearby area of Western Sarawak. In the summer of 2010 they made evening searches along the 1,329 meter high ridges of the Gunung Penrissen range to look for the toad.

After months of fruitless hunting, Das decided to include higher elevations in the team’s search. Then, one night, graduate student Pui Yong Min found the small toad two meters up a tree. Later they found another.

In the end the team had found three individuals of the missing toad species — an adult female, an adult male and a juvenile, ranging in size from 51 mm to 30 mm. All three toads exhibited those gangly limbs and the brightly colored patterns on their backs.

Talking about his team’s discovery in a press release, Das says, “They remind us that nature still holds precious secrets that we are still uncovering, which is why targeted protection and conservation is so important.”

Robin Moore of Conservation International agrees, saying in the release, “it is good to know that nature can surprise us when we are close to giving up hope, especially amidst our planet’s escalating extinction crisis.”

The slender-legged critter is only the second species on the “World’s Top 10 Most Wanted Lost Frogs” list to be found. In September 2010, the Rio Pescado Stubfoot Toad was rediscovered in Ecuador after 15 years of hiding. The spotty frog is sadly clinging on to survival.

The other frogs include the Costa Rican golden toad, the Australian gastric brooding frog, the Mesopotamia beaked toad from Colombia, Jackson’s climbing salamander, the African painted frog, the Venezuelan scarlet frog, the hula painted frog and the Turkestanian salamander — this hide and seek champion hasn’t been seen since 1909.

Image: Indraneil Das/Conservation International

Source: Wired.co.uk

See Also:

 
 

Triceratops Bones Support Asteroid Extinction Theory

13 Jul

By Mark Brown, Wired UK

Palaeontologists in America have discovered the youngest known dinosaur bones, after digging up the fossilized remains of a Triceratops or Torosaurus’ 45cm-long brow horn.

But what makes this find — from the Hell Creek Formation in the wastelands of south-east Montana — even more special is its ramifications for the current theories on what wiped out the prehistoric lizards.

It’s generally believed that a colossal asteroid pummeled into Mexico’s Yucatan Peninsula about 65 million years ago, which led to a mass extinction of any animal that couldn’t fly, swim or burrow into the ground.

But some skeptics believe that the dinosaurs were already on a sharp decline, or even extinct, when the asteroid hit. This would have been thanks to climate change, unpredictable sea levels and intense volcanic activity.

This dissenting theory has come to prominence because no fossils have even been found within three meters of the Cretaceous-Tertiary (K-T) boundary — an area in the sedimentary rock that’s packed with rare elements like Iridium and Quartz, which signifies when the asteroid impacted the planet.

This newly discovered brow horn was found just 13cm below that all-important line. It proves that this Ceratopsian dinosaur (probably a Triceratops or Torosaurus) was wandering about right up to the impact event, and the authors believe this debunks the dissenting theory.

In the paper, published in Biology Letters, the team writes: “The in situ specimen demonstrates that a gap devoid of non-avian dinosaur fossils does not exist and is inconsistent with the hypothesis that non-avian dinosaurs were extinct prior to the K-T boundary impact event.”

Image: Daderot/Wikipedia

Source: Wired.co.uk

See Also:

 
 

What is the point of pruney fingers?

28 Jun

The common wisdom is that your fingers wrinkle when they’re wet because they absorb water. But Mark Changizi thinks there’s more to it than that. According to him, pruney fingers are an adaptation to help humans, and probably other primates, get a better grip during wet conditions. They act like the rain treads on tyres. Mark lays out his hypothesis in a wonderful paper that I wrote up as a news story for Nature News.

Here’s the start; click through for the whole thing.

The wrinkles that develop on wet fingers could be an adaptation to give us better grip in slippery conditions, the latest theory suggests.

The hypothesis, from Mark Changizi, an evolutionary neurobiologist at 2AI Labs in Boise, Idaho, and his colleagues goes against the common belief that fingers turn prune-like simply because they absorb water.

Changizi thinks that the wrinkles act like rain treads on tyres. They create channels that allow water to drain away as we press our fingertips on to wet surfaces. This allows the fingers to make greater contact with a wet surface, giving them a better grip.

Scientists have known ...

 
 

50 Photos Of Basset Hounds Running

16 Mar

Our “Basset Hounds Running On The Beach” post was such a success, we thought, wait a second… there are probably hundreds of dozens of photos capturing the brilliance of a basset hound running.

Presenting 50 Photos Of Basset Hounds Running

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BONUS: The necessary close-up you’ve all been waiting for

You know the drill: E-mail this to your Mom so that she can spam her co-workers with the link.

 
 

Sperm Whales May Have Names

14 Mar

Subtle variations in sperm-whale calls suggest that individuals announce themselves with discrete personal identifier. To put it another way, they might have names.

The findings are preliminary, based on observations of just three whales, so talk of names is still speculation. But “it’s very suggestive,” said biologist Luke Rendell of Scotland’s University of St. Andrews. “They seem to make that coda in a way that’s individually distinctive.”

Rendell and his collaborators, including biologists Hal Whitehead, Shane Gero and Tyler Schulz, have for years studied the click sequences, or codas, used by sperm whales to communicate across miles of deep ocean. In a study published last June in Marine Mammal Sciences, they described a sound-analysis technique that linked recorded codas to individual members of a whale family living in the Caribbean.

In that study, they focused on a coda made only by Caribbean sperm whales. It appears to signify group membership. In the latest study, published Feb. 10 in Animal Behavior, they analyzed a coda made by sperm whales around the world. Called 5R, it’s composed of five consecutive clicks, and superficially appears to be identical in each whale. Analyzed closely, however, variations in click timing emerge. Each of the researchers’ whales had its own personal 5R riff.

‘This is just the first glimpse of what might be going on.’

The differences were significant. The sonic variations that were used to distinguish between individuals in the earlier study depended on a listener’s physical relationship to the caller: “If you record the animal from the side, you get a different structure than dead ahead or behind,” said Rendell. But these 5R variations held true regardless of listener position.

“In terms of information transfer, the timing of the clicks is much less susceptible” to interference, said Rendell. “There is no doubt in my mind that the animals can tell the difference between the timing of individuals.” Moreover, 5R tends to be made at the beginning of each coda string as if, like old-time telegraph operators clicking out a call sign, they were identifying themselves. Said Rendell, “It may function to let the animals know which individual is vocalizing.”

Audio: From a 2008 study of overlapping codas in pairs of sperm whales. One animal produces 1+1+3, the apparent group-level identifier. Both then produce overlapping 4R codas. After that, the first whale continues with 4R, while the other switches to 1+1+3. Finally, both make 1+1+3. The full meaning of such exchanges remains unclear, but they appear to reinforce social bonding.

Rendell stressed that much more research is needed to be sure of 5R’s function. “We could have just observed a freak occurrence,” he said. Future research will involve more recordings. “This is just the first glimpse of what might be going on.”

That individual whales would have means of identifying themselves does, however, make sense. Dolphins have already been shown to have individual, identifying whistles. Like them, sperm whales are highly social animals who maintain complex relationships over long distances, coordinating hunts and cooperating to raise one another’s calves.

Sperm-whale coda repertoires can contain dozens of different calls, which vary in use among families and regions, as do patterns of behavior. At a neurological level, their brains display many of the features associated in humans with sophisticated cognition. Many researchers think that sperm whales and other cetacean species should be considered “non-human persons,” comparable at least to chimpanzees and other great apes.

Compared to primates, however, studying the behaviors and relationships of whales is extremely difficult. They don’t take well to aquariums, and observations in the wild take place on their aquatic terms.

What’s been observed so far are just “the crude behavioral measures we get by following them in a boat,” said Rendell. “I’d argue that there is probably a vast amount of complexity out there in sperm whale society that we have yet to understand. As we get to know more about them, we’re going to continue to reveal complexities that we didn’t anticipate.”

Image: NOAA. Audio: Luke Rendell.

See Also:

Citation: “Individually distinctive acoustic features in sperm whale codas.” By Ricardo Antunes, Tyler Schulz, Shane Gero, Hal Whitehead, Jonathan Gordon, Luke Rendell. Animal Behavior, Feb. 10, 2011.

 
 

Dolphins Save Doberman From Drowning in Florida Canal

06 Mar
doberman photo Photo: shioshvili Last week concerned dolphins successfully saved the life of a struggling Doberman Pinscher by alerting a vacationing couple that the poor pooch was stuck on the sandbar. The dolphins were enjoying a swim through the Florida canal on their way to the Gulf of Mexico when they noticed the 80 pound Doberman that had disappeared hours before. See how they saved the pup and why this incredibly intelligent species is under new threats. ...Read the full story on TreeHugger
 
 

Mass Extinctions Change the Rules of Evolution

02 Sep

A reinterpretation of the fossil record suggests a new answer to one of evolution’s existential questions: whether global mass extinctions are just short-term diversions in life’s preordained course, or send life careening down wholly new paths.

Some scientists have suggested the former. Rates of species diversification — the speed at which groups adapt and fill open ecological niches — seemed to predict what’s flourished in the aftermath of past planetary cataclysms. But according to the calculations of Macquarie University paleobiologist John Alroy, that’s just not the case.

“Mass extinction fundamentally changes the dynamics. It changes the composition of the biosphere forever. You can’t simply predict the winners and losers from what groups have done before,” he said.

Alroy was once a student of paleontologist Jack Sepkoski, who in the 1980s formalized the notion that Earth has experienced five mass extinctions in the 550 million years since life became durable enough to leave a fossil record. Graphs of taxonomic abundance depict lines rising steadily as life diversifies, plunging precipitously during each extinction, and rising again as life proliferates anew.

As the fossil record is patchy and long-term evolutionary principles still debated, paleobiologists have historically disagreed about what these extinctions mean. Some held that, in the absence of extinctions, species would diversify endlessly. The Tree of Life could sprout new branches forever. Others argued that each taxonomic group had limits; once it reached a certain size, each branch would stop growing.

Sepkoski’s calculations put him on the limits side of this argument. He also proposed that, by looking at the rate at which each group produced new species, one could predict the winners and losers of each mass extinction’s aftermath. Groups that diversified rapidly would flourish. Their destiny was already established.

“It’s a clockmaker vision of evolution. Each group has fixed dynamics, and if there’s an extinction, it just messes it up a bit,” said Alroy. “That’s what I’m challenging in this paper. There are limits, and that’s why we don’t have a trillion species. But those limits can change.”

Alroy crunched marine fossil data in the Paleobiology Database, which gathers specimen records from nearly 100,000 fossil collections around the world. He used a statistical adjustment method designed to reduce the skewing influences of paleontological circumstance — the greater chances of finding young fossils rather than old, the ease of studying some types of rock rather than others.

Historical species diversity among marine animals of Cambrian, Paleozoic and Modern origin.

The analysis, published September 2 in Science, produced what Alroy considers to be the most accurate reflection of extinction dynamics to date. And while his data supported the notion that each group’s diversity eventually hits a limit, he didn’t find Sepkoski’s correlation between pre-mass-extinction diversity rates and post-extinction success. Each mass extinction event seemed to change the rules. Past didn’t indicate future.

In an accompanying commentary, paleontologist Charles Marshall of the University of California, Berkeley noted that Alroy’s statistical methods still need review by the paleobiology community. The Paleobiological Database, for all its thoroughness, might also be incomplete in as-yet-unappreciated ways. “There will be no immediate consensus on the details of the pattern of diversity,” he wrote. But “the pieces are falling into place.”

Enough pieces have come together for Alroy to speculate on his findings’ implication for the future, given that Earth is now experiencing another mass extinction. Starting with extinctions of large land animals more than 50,000 years ago that continued as modern humans proliferated around the globe, and picking up pace in the Agricultural and Industrial ages, current extinction rates are far beyond levels capable of unraveling entire food webs in coming centuries. Ecologists estimate that between 50 and 90 percent of all species are doomed without profound changes in human resource use.

In the past, many evolutionary biologists thought life would eventually recover its present composition, said Alroy. In 100 million years or so, the same general creatures would again roam the Earth. “But that isn’t in the data,” he said.

Instead Alroy’s analysis suggests that the future is inherently unpredictable, that what comes next can’t be extrapolated from what is measured now, no more than a mid-Cretaceous observer could have guessed that a few tiny rodents would someday occupy every ecological niche then ruled by reptiles.

“The current mass extinction is not going to simply put things out of whack for a while, and then things will go back to where we started, or would have gone anyway,” said Alroy. Mass extinction “changes the rules of evolution.”

Images: 1) A fossil skull of Dunkleosteus, an apex predator fish that lived between 380 million and 360 million years ago, and had what is believed to be history’s most powerful bite./Michael LaBarbera, courtesy of The Field Museum. 2) Graph of species diversity among marine animals of Cambrian, Paleozoic and Modern origin./Science.

See Also:

Citations: “The Shifting Balance of Diversity Among Major Marine Animal Groups.” By J. Alroy. Science, Vol. 329 No. 5996, September 3, 2010.

“Marine Biodiversity Dynamics over Deep Time.” By Charles R. Marshall. Science, Vol. 329 No. 5996, September 3, 2010.

Brandon Keim’s Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points.