Ask a group of snake researchers whether our modern snakes evolved from land-loving or ocean-loving lizards, and you’re likely to start a heated argument. But the days of snake-origin squabbles may be coming to a close–researchers have created the first 3-D images of snake fossils and have discovered that their legs are more akin to the legs of land-dwelling lizards than they are to the ocean-dwelling kind.
The researchers studied a 95-million-year-old fossilized snake called Eupodophis descouensi that was found in present-day Lebanon. Published in the Journal of Vertebrate Paleontology, the scientists used a novel 3-D imaging technique called synchrotron-radiation computed laminography:
“Synchrotrons are enormous machines and allow us to see microscopic details in fossils invisible to any other techniques without damage to these invaluable specimens,” said co-author Paul Tafforeau from the European Synchrotron Radiation Facility. [Discovery News]
This fossil of an ancient winged reptile, bought from a farmer in China’s Liaoning province, tells a dramatic tale. About 160 million years ago, a female pterosaur fractured its wing and sank to the bottom of a muddy lake. Somehow, in the process of either dying or decomposing, she expelled a single egg, which has been preserved through the ages.
That’s the story that researchers told in a study published in the journal Science, anyway. And if the remarkably preserved fossil of the reptile Darwinopterus is female, they say, it sheds light on the sex differences and mating rituals of the extinct species. The preserved egg also seems to reveal new details of pterosaur reproduction.
Pterosaurs were the first vertebrates to take to the air, first appearing in the fossil record some 220 million years ago in the late Triassic period. Before their demise 65 million years ago the group evolved to include the largest flying animals ever to live – some had a wingspan of 10 metres. [New Scientist]
They may not be as adorable as sugar gliders, but they’re just as accomplished: Five species of Asian snake have also developed the ability to “fly” or glide from tree to tree, flattening out their bodies to travel up to 80 feet.
Researcher Jake Socha and his team studied the glide of Chrysopelea paradisi snake and took videos of the snakes in flight, which Socha presented at an ongoing meeting of the American Physical Society. He found that before a snake takes the leap it curls its body into a J-shape, and then launches itself from the tree branch. In the air, it flattens its body and undulates, as if slithering through the air.
The snake differs from other gliding species, like gliding lizards and flying squirrels, in that it doesn’t have specialized body parts that act as wings.
“The whole snake itself is just one long wing,” Socha said. “That wing is constantly reconfiguring, it’s constantly reforming and contorting.” [LiveScience]
Hit the jump for a video of the snake in action. (more…)
A tiny fraction of vertebrate species have ever been seen reproducing through parthenogenesis, the fatherless birth of offspring in which the embryo develops without fertilization by a male. Now you can add boa constrictors to that short list: A study in Biology Letters documents the case of a boa that gave birth to 22 offspring over the last two years, all of whom are female and born this unusual way.
“Only with the development and application of molecular tools have we truly begun to understand how common this form of reproduction may be,” lead author Warren Booth [says]. Booth, a research associate at North Carolina State University’s Department of Entomology, and his team first suspected something was up when the mother boa constrictor gave birth, twice, to a total of 22 caramel-colored females. The males housed with the female did not carry the gene for this recessive color trait. [Discovery News]
When Booth’s team analyzed the DNA of the young snakes, they found no evidence of paternity by any of the males who’d mated with their mother previously. Furthermore, the chromosomes of the 22 young gave them away.
While the temperature effects of climate change are expected to be less dramatic in the equatorial regions, the cold-blooded tropical animals that live there may be in for a dramatic shock.
A study published this week in Nature focused on these cold-blooded animals–including insects, amphibians, and lizards–whose body temperatures are not constant, but instead rise and fall with the temperature of their environment. The researchers found that these creatures show great increases in their metabolism from slight changes in temperature; the metabolic increases were on the order of twice that of warm-blooded animals.
“The assumption has been that effects on organisms will be biggest in the place where the temperature has changed the most,” [first author Michael] Dillon said. “The underlying assumption is that … no matter where you start, a change means the same thing. But with physiology, that’s rarely the case.” [Scientific American].
This means that though climate change will be more extreme in toward the Earth’s poles, the cold-blooded animals that live near the equator (where changes should be milder) may react more strongly to the changes.
During the Pleistocene epoch animals thought big: It was the age of the megafauna, when creatures like the mammoth, an 8-foot-long beaver, and a hippopotamus-sized wombat walked the Earth. But these giants vanished one by one, and scientists have long wondered why.
Debate over what caused the megafauna to die out has raged for 150 years, since Darwin first spotted the remains of giant ground sloths in Chile. Possible causes have ranged from human influence to climate change in the past, even to a cataclysmic meteor strike. [BBC]
Now, a discovery on the South Pacific island nation of Vanuatu seems to have answered the question for at least one species. Researchers have turned up the bones of a giant land turtle in a dump used by the people who settled on the islands 3,000 years ago, and lead researcher Trevor Worthy says the evidence strongly suggests that the turtles were hunted into extinction.
80beats aims to bring you all the science news that’s fit to turn into bytes of digital information, but sometimes DISCOVER’s other bloggers get to the juicy news stories first. To make sure you don’t miss anything, here are a couple of links:
Supersenses! Ed Yong at Not Exactly Rocket Science covers two journal articles in which scientists investigated the amazing sense of touch in seal whiskers and sharks’ equally astounding sense of smell in the water. To test the sensitivity of seal whiskers, researchers blindfolded a seal and had him “read” the turbulence of a wake.
For the first time, scientists get to watch as an exoplanet orbits its star—63 light years away. Check out Phil Plait’s Bad Astronomy post for the must-see image. Elsewhere on the Web, National Geographic notes that this planet, Beta Pictoris b, is just a baby. According to the paper published in Science, Beta Pictoris appears to be only a few million years old, yet it’s fully formed–which surprised astronomers who thought that planets take much longer to come into their own.
Finally, a look back to the marine reptiles that ruled the prehistoric seas. A new study suggests that unlike most reptiles, these mighty sea monsters may have been able to regulate their body temperatures, reports Ed Yong. That ability could have allowed these top-of-the-food-chain hunters to swim fast and dive deep, regardless of ocean temperatures.
The turn of the millennium was not kind to the snakes.
Herpetologist Chris Reading and his team have been counting snakes through their own surveys and looking at population data going back to 1987 to see what’s happening to snake populations. The alarming findings, to be published soon in Biology Letters, indicate that most of the species studied saw a great decrease in population, with the greatest loss between 1998 and 2002.
Reading’s team monitored 17 different species in different climates—including snakes from Europe, Africa, and Australia—to try to get a global picture. Eleven of the 17 declined sharply over the study’s two-decade-plus period, with some declining as much as 90 percent. Five remained more or less stable. Only one saw a population increase, and a very slight one at that.
“All the declines occurred during the same relatively short period of time and over a wide geographical area that included temperate, Mediterranean and tropical climates,” write the authors. “We suggest that, for these reasons alone, there is likely to be a common cause at the root of the declines and that this indicates a more widespread phenomenon” [Guardian].
Crocodiles like to lurk in the shallows, preparing to pounce. They are not, as a general rule, strong enough swimmers to go on extended ocean cruises whenever they feel like it. Despite this, these creatures managed to reach islands across the South Pacific. How?
Surfing.
A group of scientists led by Craig Franklin, and including the late “Crocodile Hunter” Steve Irwin, studied saltwater crocs from the Kennedy River area of Northeastern Australia for about a year for a study forthcoming in the Journal of Animal Ecology. The team tagged 20 animals with receivers to give both their position and body temperature.
They found that eight crocodiles undertook a total of 42 long-distance journeys of more than 10 kilometres [6.2 miles] per day. In 96% of these trips, the reptiles traveled with the current flow. In contrast, the crocodiles were equally likely to travel with and against the current flow when making short journeys [Nature].
The body temperature reading gave the scientists another way to verify this, besides matching croc travel habits to changing ocean currents. When the tide went against the crocs, they just hung out on the beach and their body temperature rose to 90 degrees F as they soaked up the sun. However, when the current became favorable and they went traveling, their temperatures descended to more like 77 degrees.
We already knew that great numbers of sea turtles are killed when they’re caught up in the nets used by fishing operations around the world. But according to a study in Conservation Letters, the actual number of turtles accidentally killed over the last two decades has been vastly underestimated: Rather than counting in tens of thousands, study author Bryan Wallace argues, commercial fishing has probably killed sea turtles in the millions.
The official records show about 85,000 turtles killed by fishing operations from 1990 to 2008. But Wallace, the science adviser for Conservation International’s sea turtle program, says that’s deceptively small accounting. “Because the reports we reviewed typically covered less than 1% of all fleets, with little or no information from small-scale fisheries around the world, we conservatively estimate that the true total is probably not in tens of thousands, but in the millions of turtles taken as bycatch in the past two decades,” said Dr Wallace [BBC News]. Six of the seven sea turtle species are presently listed as in danger. They include loggerheads, leatherbacks, hawksbills, Olive Ridleys, Kemp’s Ridleys and green sea turtles; the flatback, an endemic to Australia, is currently categorized as Data Deficient [CNN].
Some of the weird wildlife on Madagascar—its mammals especially—probably arrived there by rafting from mainland Africa, we reported back in January. But not its blind snakes. According to a study out now in Biology Letters, these funny-looking creatures date back 150 million years to the Gondwana landmass, and have lived on Madagascar since before it broke off from India and drifted away. And, the researchers say, their story of spreading around the world carries many more twists.
Growing to about a foot long, blind snakes act a lot like worms, burrowing under the surface of every continent except Antarctica. Unlike worms, though, blind snakes have backbones and tiny scales [National Geographic]. They earned their moniker by having blurry vision and sensing chemicals through their skin to find their way around. But despite having backbones, there are few blind snakes in the fossil record, making it hard for researchers to study their evolutionary history. So lead researchers Blair Hedges and Nicolas Vidal had to rely on living species. They extracted five nuclear genes, which code for proteins, from 96 different species of worm-like snakes to reconstruct the branching pattern of their evolution, allowing the team to estimate the times of divergence of different lineages using molecular clocks [UPI].
When it comes to picking up clever tricks and learning to do something the way everybody else does it, social animals like humans, birds, and monkeys excel. One individual looks at what others in the group are doing and quickly learns to follow suit—an invaluable skill that scientists previously thought evolved in step with communal living.
But what about an individual that doesn’t live in a group and spends most of its life in solitude–would it still have that ability to watch and learn? Cognitive biologist Anna Wilkinson set out to answer that question by studying the red-footed tortoise, one of the loneliest beasts on the planet. These South American tortoises grow up without parents or siblings, and adults rarely cross paths. If a head-bobbing display determines that a stranger is of the opposite sex, the two will mate perfunctorily–otherwise they just ignore each other [ScienceNOW]. Yet in a new study published in Biology Letters, Wilkinson showed that even these hermits possess the ability to learn by watching others.
Hot, cold, in between, it doesn’t really matter to chameleons: They’re going to snare their prey anyway, according to findings in this week’s Proceedings of the National Academy of Sciences. That’s because their elastic tongues are designed like ballistic weapons.
Chameleons fire their tongues at breakneck speed, says study leader Christopher Anderson. “A chameleon’s tongue travels at accelerations exceeding 400 meters (1,312 feet) per second squared, or about 41 Gs of force,” he added. To put that into perspective, a space shuttle only develops about three Gs of force when it takes off [Discovery News]. Given that muscle performance diminishes when it gets colder, and that these lizards are ectothermic (cold-blooded), one might think their tongue prowess would trial off sharply as temperatures drop.
Not so, Anderson says. He and his team filmed veiled chameleons (Chamaeleo calyptratus) eating crickets, and controlled the temperature as they watched. For other cold-blooded creatures, the researchers say, an 18-degree Fahrenheit drop in the temperature causes a 33 percent decrease in muscle speed, and an even more dramatic drop-off in the speed of tongue movements. But the chameleons had tongue snaps that only slowed by about 10 to 19 percent … with the same temperature decrease [Scientific American]. The chameleons’ tongues also extended to their full glory despite the temperature change.
Take a good look: according to a new study in PLoS Biology, what you see in this image is a snake about to prey on dinosaur eggs, a 67-million-year-old scene frozen in time and finally discovered. It’s the first time that a snake has been seen eating a dinosaur. The snake is that bit of bones on the left, lead researcher Jeff Wilson says. The egg in the top right contains a tiny titanosaur, one of largest dinosaur groups to ever walk the Earth.
“The snake (Sanajeh indicus) probably lived around the nesting ground and preyed upon hatchlings. They all died instantly when they were covered by a big pulse of sediment from a nearby hill loosened by a storm,” says Wilson [New Scientist]. Wilson guesses that a storm or some other malady might have led the enormous adult dinos to leave the nest, opening the door for the snake to slither in, wait for the baby dinos to hatch, and snack on them. But it never got the chance.
Sure, creatures that reproduce asexually get to avoid some of the hangups that come with sex, but the strategy brings its own problems. First and foremost, how do you prevent genetic deterioration without the fresh infusion of new genes that results from the mixing of male and female DNA? For the all-female whiptail lizard, the solution is to hedge its bets.
In a study forthcoming in Nature, researcher Peter Baumann found that each whiptail lizard egg cells contains twice the number of chromosomes you’d expect. In the fertilized egg cell of a sexually reproducing lizard species, you’d expect to see much what you see in humans—23 chromosomes from the father and 23 from the mother combining into 46. (Most human cells contain 46 chromosomes, but egg and sperm cells contain only 23, so that they can combine to give an offspring a compete, but genetically new, set of chromosomes.)
But the whiptail eggs instead begin with two identical copies of each of their mother’s chromosomes, for a total of 92. Those chromosomes then pair with their identical duplicates, and after two cell divisions, a mature egg with 46 chromosomes is produced. Since crossing-over during the cell divisions occurs only between pairs of identical chromosomes, the lizard that develops from the unfertilized egg is identical to its mother [The New York Times].
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
A tiny fraction of vertebrate species have ever been seen reproducing through 
While the temperature effects of climate change are expected to be less dramatic in the equatorial regions, the cold-blooded tropical animals that live there may be in for a dramatic shock.
During the 
80beats aims to bring you all the science news that’s fit to turn into bytes of digital information, but sometimes DISCOVER’s other bloggers get to the juicy news stories first. To make sure you don’t miss anything, here are a couple of links:
The turn of the millennium was not kind to the snakes.
Crocodiles like to lurk in the shallows, preparing to pounce. They are not, as a general rule, strong enough swimmers to go on extended ocean cruises whenever they feel like it. Despite this, these creatures managed to reach islands across the South Pacific. How?
We already knew that great numbers of sea turtles are killed when they’re caught up in the nets used by fishing operations around the world. But according to a 
Some of the weird wildlife on Madagascar—its mammals especially—probably arrived there by rafting from mainland Africa, 
When it comes to picking up clever tricks and learning to do something the way everybody else does it, social animals like humans, birds, and monkeys excel. One individual looks at what others in the group are doing and quickly learns to follow suit—an invaluable skill that scientists previously thought evolved in step with communal living.
Hot, cold, in between, it doesn’t really matter to chameleons: They’re going to snare their prey anyway, according to 
Take a good look: according to a new 
Sure, creatures that reproduce asexually get to avoid some of the hangups that come with sex, but the strategy brings its own problems. First and foremost, how do you prevent genetic deterioration without the fresh infusion of new genes that results from the mixing of male and female DNA? For the all-female whiptail lizard, the solution is to hedge its bets.
