Alligators breathe like birds, with a one-way tube that flows all the way through their respiratory systems. While that might not seem earth-shattering at first, alligators and birds diverged 246 million years ago. And according to a new study in Science, that means this breathing technique goes way, way back, and could even explain how the ancestors of dinosaurs survived the great Permian-Triassic extinction.
Unlike a mammal’s breath, which exits the lungs from the same dead-end chambers it enters, a bird’s breath takes a loopy one-way street through its lungs [Science News]. This breathing technique allows birds to explore high altitudes where oxygen levels drop off significantly.
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Today it’s tempting to think of Antarctica as an icy wasteland, hospitable for penguins and seals but not much else. However, before the continent was covered by a permanent ice sheet, it may have been a refuge from a world in chaos, according to findings published in a journal called Naturwissenschaften.
Jörg Fröbisch of Chicago’s Field Museum says that a distant relative of mammals, a cat-sized herbivore called Kombuisia antarctica survived the Permian-Triassic Extinction 250 million years ago by migrating from southern Africa to Antarctica. At the time of the end-Permian extinction, Antarctica was some distance north of its present location, warmer than it is today, and not covered with permanent glaciers [The Telegraph].
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A fungus found within ancient mammoth dung is providing scientists with clues about how the large ancient mammals collectively known as megafauna went extinct. The fungus, Sporormiella, produces spores in the dung of large herbivores. These are then preserved in the layers of mud and can provide an index of the number of these animals, or megafauna, that roamed the environment at a particular time [BBC News]. For a new study, researcher Jacquelyn Gill collected and analyzed spores in sediment samples from an Indiana lake and several sites in New York.
From Gill’s analysis, published in the journal Science, she concluded that North American megafauna began a slow decline around 15,000 years ago and vanished about 1,000 years later. The data suggests megafauna started going extinct much earlier than previously though, which basically wipes out two theories of their extinction.
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Say you’re a goat stuck on a Mediterranean island with scarce food and no way to leave. How do you survive? The strange species Myotragus answered that question by getting small, and, most unusually, adopting the cold-bloodedness normally seen in reptiles.
In a paper in this week’s Proceedings of the National Academy of Sciences, researchers say that the now-extinct dwarf goat managed to survive thousands of years of resource scarcity by adjusting its metabolism to match how much food was available. The discovery marks the first time scientists have seen this cold-blooded survival strategy in mammals. The surprising skill likely allowed the goats to endure potentially fatal periods of scarcity on what is now the Spanish island of Majorca [National Geographic News].
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The chytrid skin fungus is killing frogs around the world, and researchers worry that it is already driving some species to extinction–but until now, no one understood how the fungus killed. Now, new research shows that the fungus disrupts the flow of nutrients through the frogs’ skin, ultimately leading to cardiac arrest.
In the study, which will be published tomorrow in Science, the scientists found that the fungus interferes with the frogs’ ability to absorb electrolytes, the electrically conducive molecules that are vital for muscle and nerve function. Diseased green tree frogs had dramatically lower levels of potassium and sodium in their blood and urine. Says study coautor Wyatt Voyles: “It’s a failure of the electrical system, leading to mechanical failure. If you don’t have a normal electrical system pacing the heart, it won’t pump blood” [Wired.com].
Further experiments confirmed that the electrolyte imbalance led to a heart shutdown. The scientists took electrocardiogram recordings of the frogs’ hearts in the hours before death; and found changes to the rhythm culminating in arrest. Drugs that restore electrolyte balance brought the animals a few hours or days of better health, some showing enough vigour to climb out of their bowls of water; but all died in the end [BBC News]. Researchers’ next task will be to determine exactly how the fungus interferes with the electrolyte absorption: it could be a result of cell damage in the skin, or a toxin produced by the fungus.
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Image: Jamie Voyles, Alex Hyatt, and Frank Fillipi
Saving Tasmanian devils from the infectious cancer that has quickly rendered the small marsupials an endangered species will be an even harder than we realized, according to a new study. The latest bad news from Tasmania: Researchers have found that devils are not solitary creatures with small social networks, but instead frequently interact with other devils, allowing for faster spread of the disease. The devastating cancer, known as devil facial tumor disease, is spread by biting, something the aggressive animals apparently do a lot of.
Investigating the social behaviour of devils, which are nocturnal, forest-dwelling and mate underground is tricky [ABC Science], notes lead researcher Rodrigo Hamede. To get around this difficulty, Hamede outfitted 46 wild devils in a disease-free area with radio collars that recorded every time one devil approached within 12 inches of another–close enough to bite. The scientists found that all 27 of the devils from which intact collars were recovered belong to a single large social group. Each animal is connected to all the others, either directly or through connections with other animals. The finding suggests that if any one of the animals becomes infected with the facial tumor disease, the cancer would spread to the entire network [Science News].
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It may seem as though orangutans’ 180-pound bodies would be unwieldy when it comes to swinging from delicate tree branches in the rainforests of Indonesia and Malaysia. But the animals have figured out a variety of ways to navigate treetops, allowing them to avoid a potentially deadly fall, according to a study published in the Proceedings of the National Academy of Sciences.
When scientists observed wild orangutans in the Sumatran rainforest, they found that the animals traversed the delicate branches by moving their bodies with a rhythm that counters the vibrations of the trees. At the highest treetops in the forest, tree branches are thin and begin to wobble as animals climb on them, much as a suspension footbridge vibrates as people walk over it. Too much vibration and an orangutan can be thrown off altogether. From high in the trees, such a fall would be deadly [Time]. But because orangutans move with an irregular beat, they avoid compounding the already-shaking branches with the motion of their own bodies. Also increasing their stability, the animals also have the habit of grasping more than one branch at once–in fact, nearly one-third of the time, orangutans held on to more than four branches simultaneously.
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As the International Whaling Commission wound down this week with no progress made on the stalemate between pro-whaling and anti-whaling nations, some experts are beginning to question the commission’s central tool: the moratorium on commercial whaling established more than 20 years ago.Some experts wonder whether the ban is really protecting the world’s whale populations. Japan’s so-called “scientific whaling” program is a loophole in the ban, and the program is widely seen as a cover for commercial whaling. Japan catches more than 1,000 whales a year, and most cetacean researchers argue that whale populations exist at only a fraction of their former abundance and are far from large enough to sustain commercial harvesting for meat or oil — or even the culling of some 1,000 whales a year for science. Australia, a party to the IWC, campaigned this year to end any ”scientific whaling” that involves the deliberate killing of whales [Science News].
A report released by the commission on Monday also states that a quarter of the whales harvested from the Antarctic Ocean in the last seven months by Japanese researchers were pregnant. To many, the destruction of these whales and their unborn calves makes a mockery of the moratorium on whaling, given that the goal of the ban is to preserve whale populations. However, the Japanese Whaling Association contends on its Web site that “No whales have ever been hunted to extinction, nor are they likely to be. . . . [And] there are species which are abundant enough that marine management is needed,” such as for the Antarctic and northwestern Pacific minke whales and northwestern Pacific Bryde’s whales [Science News].
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Extinction threatens four more species of deep-sea sharks and rays than a year ago, bringing the total species classified as “threatened” to 20 species, or nearly a third of the world’s 64 species, according to a report (pdf) released today by the International Union for Conservation of Nature. Rays and sharks are already two of the most endangered fish groups, researchers say.
The threat facing pelagic sharks and rays stems largely from overfishing; in many parts of the world, shark meat is considered a delicacy, and some animals become ensnared in fishing nets intended to catch tuna or swordfish. The report also urges governments to halt shark “finning,” the slicing of fins from captured sharks which are then tipped back into the sea to die, which it says is a growing industry providing ingredients for the Asian delicacy, shark fin soup. Although finning bans have been declared in most global waters, little effort is made to enforce them, said the IUCN [Reuters].
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The giant, prehistoric kangaroo that once hopped over the Australian landscape may have been wiped out by the first human settlers on that continent, a new study argues. In making this claim, the researchers are entering into a long-running debate over whether Australia’s “megafauna,” which also included marsupial lions and hippo-sized wombats, were driven extinct by the changing climate or by overzealous hunting. And while the new study, which will be published in the Proceedings of the National Academy of Sciences, makes an interesting case for the latter hypothesis, some researchers are not convinced.
Researchers analyzed the teeth of the nearly seven-foot-tall kangaroo, known as Procoptodon goliah, to determine what it ate and drank. Different sources of water and food leave trace amounts of particular types, or isotopes, of hydrogen and carbon atoms, which are deposited in the teeth like a recorded diet. Additionally, tiny patterns of wear give clues about the type of food a given creature chewed. The team concluded that the giant kangaroos fed mainly on saltbush shrubs [BBC News]. These hardy bushes thrive in arid conditions, which makes it less likely that the kangaroos ran out of food as the continent’s climate got hotter and drier.
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In a rare conservation success, a beautiful butterfly species that was headed for extinction has been brought back from the brink, thanks to careful biological observations of the insect‘s life cycle. The mysterious disappearance of the Large Blue Butterfly across most of northern Europe was originally put down to its popularity among insect collectors [Telegraph]. Then biologist Jeremy Thomas spent six summers in the 1970s studying the very last colony of large blue butterflies in the United Kingdom, and determined that the butterflies were dependent on one species of red ant for their survival–and those ants were losing their habitat.
The butterflies lay their eggs on flowering thyme plants, and the hatched caterpillars fall to the ground and begin to impersonate immature red ants. They secrete chemicals and even make noises that make the red ants believe they are wayward grubs. The ants then mistakenly carry the caterpillars to their underground homes and keep looking after them even though the adopted intruders gobble ant grubs for 10 months before forming a chrysalis and flying away as adult butterflies [Reuters].
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Scientists have long known that coral reefs are being threatened by disease, global warming and other factors. Now a new study shows that that majority of Caribbean reefs have, in fact, been “flattened” in the past four decades, as ornate branched corals have died out and been replaced by flatter, fast-growing “weedy” species. Most of the reefs have lost all the intricate, tree-like corals that until the 1970s provided sanctuary for unique reef fish and other creatures, as well as protecting coastlines by sapping the energy of waves [New Scientist], according to the report, published in the journal Proceedings of the Royal Society B.
The coral reefs that were initially the most complex have almost been completely eliminated, says the researchers, who analysed changes in the structure of reefs using 500 surveys across 200 reefs conducted between 1969 and 2008. They found that 75 per cent of the reefs are now largely flat, compared with 20 per cent in the 1970s [ScienceDaily]. That’s bad news for sea life and storm defenses, says study coauthor Lorenzo Alvarez-Filip: “For many organisms, the complex structure of reefs provides refuge from predators…. This drastic loss of architectural complexity is clearly driving substantial declines in biodiversity, which will in turn affect coastal fishing communities” [ScienceDaily].
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The explosion of a volcano located in present-day China might have caused a mass extinction 260 million years ago, adding more evidence that volcanoes might have been to blame for some of the world’s most catastrophic die-offs. Because the eruptions occurred in a shallow sea the researchers were able to study both the volcanic rock and the overlying layer of sedimentary rock containing fossilized marine life [AP], giving researchers a better picture of how the explosion altered the balance of life.
The injection of hot lava in a sea would have produced a massive cloud formation that could spread around the world, cooling the planet and producing acid rain [AP], according to the study, which was published in Science and led by paleontologist Paul Wignall. Based on analysis of the volcanic and sedimentary rock at the eruption site, the scientists hypothesized that ash and lava spewed from a sea covering the volcano, showering plants and animals with atmospheric carbon. “When fast flowing, low viscosity magma meets shallow sea it’s like throwing water into a chip pan there’s spectacular explosion producing gigantic clouds of steam” [Telegraph], says Wignall.
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Scientists say they have found fossils near the Colorado-New Mexico border that prove some dinosaurs survived the mass extinction that most researchers believe was caused by a meteor impact 65 million years ago. James Fassett, a scientist with the U.S. Geological Survey, says he has found evidence that a sizable population of ceratopsians and sauropods, a class of giant, dim-witted leaf-eaters such as the brachiosaurus, hung on for another 500,000 years in the [San Juan] basin. “There might even have been some T. rexes, based on some teeth we found” [Los Angeles Times], he said.
The bones of hadrosaurs, tyrannosaurs, anklyosaurs, and several other species were found together in a sandstone formation that dates to the Paleocene epoch—the time period after the so-called Cretaceous-Tertiary (K-T) extinction event, which is thought to have killed off the dinosaurs [National Geographic News]. To prove that the bones he found were indeed older than the extinction and eliminate the possibility that they had not simply been incorporated into newer rocks, Fassett points to his discovery of 34 bones from a single hadrosaur: If they had been washed away from their original location, they would almost certainly have been separated, not found together [Los Angeles Times].
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Continuing the controversy over whether tissue can be extracted from fossils, cell-like structures resembling blood cells have been found in the leg bone of a dinosaur excavated from a Montana site. The researchers, led by Mary Schweitzer, have sequenced a set of proteins belonging to the 80-million-year-old remains of a duck-billed hadrosaur…. confirmed the presence of collagen, laminin and elastin proteins from the bone…. [and] independently verified amino acids in dinosaur tissues [GenomeWeb].
In 2007, Schweitzer first reported finding soft tissue, and then collagen, from the leg bone of a 68-million-year-old Tyrannosaurus rex excavated two years prior. But her team’s research later proved controversial, with some questioning whether the samples they had obtained had become contaminated with proteins from modern species [Nature News]. So the team set out to replicate its findings, and searched for dinosaur fossils buried in deep sandstones, which were likely to be well preserved, and they speeded up the process of getting them from the field to the lab [Cosmos].
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