When dinosaurs ruled the land, other groups of prehistoric reptiles dominated the waters. Their bones have also fossilised and they reveal much about how these ‘sea dragons’ lived. They tell us about the shape of their bodies, the things they ate and even how they determined their sex. And according to Aurélien Bernard from the University of Lyon, they can tell us whether these reptiles could control their body temperature.

The majority of reptiles are ‘cold-blooded’. Unlike mammals and birds, they can’t generate and retain their own heat, and their body temperature depends on their surroundings. But Bernard thinks that at three groups of marine reptiles – the dolphin-shaped ichthyosaurs, the crocodile-shaped mosasaurs, and the the paddle-flippered plesiosaurs – bucked this trend. Whether in tropical or cold waters, they could maintain a constant body temperature that reached as high as 35-39 degrees Celsius.

Bernard estimated the body temperature of these ocean-going predators by studying their teeth. He took samples from 40 plesiosaurs, ichthyosaurs and mosasaurs as well as several prehistoric fish. The specimens came from five continents, and a range of periods from the Triassic to the Cretaceous. In every tooth, he measured the amount of different oxygen isotopes, a value that depends on the animal’s body temperature and the composition of the water it swallows.

The data from the fish helped to calibrate the reptile data. By and large, fish body temperatures reflect the temperatures of the surrounding seawater. If the reptiles’ teeth had the same composition of oxygen isotopes as those of the fish, their bodies were also similarly as warm as their surroundings and they were probably cold-blooded. Any differences reflect a different means of regulating body heat.

Using a mathematical model, Bernard calculated that both ichthyosaurs and plesiosaurs managed to keep a constant balmy body temperature from around 24-35°C, even when swimming through waters as cold as 12°C. The abilities of mosasaurs were less clear, but it seems that they had at least some control over their body temperature.

These results fit with the portraits of ichthyosaurs and plesiosaurs as active, fast-swimming hunters, which needed warm bodies for their fast chases and deep dives. Likewise, the ambiguity around the body temperature of mosasaurs is consistent with the idea that they were ambush predators, whose sit-and-wait strategies wouldn’t have demanded such high metabolisms.

Other lines of evidence support Bernard’s conclusion. In an earlier study, Ryosuke Motani from the Royal Ontario Museum suggested that the ichthyosaur Stenopterygius had a cruising speed and metabolic rate similar to today’s tuna. Other scientists noted that ichthyosaurs grew incredibly quickly after birth, another sign of a high metabolic rate. And finally, fossils that probably came from plesiosaurs and ichthyosaurs have been recovered from southeastern Australia, a region that would have been bitterly cold when these animals were swimming about.

However, it’s still unclear how these giant reptiles managed their body heat. Today, the giant leatherback turtle is sort of warm-blooded – its massive size allows it to retain heat more effectively than its smaller cousins, an ability known as gigantothermy. If leatherbacks can pull of this trick, it’s entirely likely that even bigger animals like the mosasaur Tylosaurus did something similar.

Modern fish, including some of the ocean’s top predators, use different tricks to warm their blood. Swordfish can temporarily raise the temperature of their brains and eyes, which gives it an edge when hunting fast-moving prey.

Tuna go one step further. Like all fish, its hard-working muscles heat up the blood that flows through them. In other fish, that heat would be lost as the blood returns to the gills for a fresh load of oxygen. But the tuna’s blood vessels are arranged so that the warm blood flowing from the muscles travels past, and heats up, cold blood coming in from the gills. This set-up keeps the heat generated by the tuna’s muscles inside its own body. Some sharks rely on a similar heat exchanger; perhaps plesiosaurs and ichthyosaurs did the same.

Reference: Science http://dx.doi.org/10.1126/science.1187443

Photos by Captmondo, Sebastian Bergmann and Piotrus

More on prehistoric marine reptiles:

How prehistoric sea monsters sorted males from females

This is extremely cool news: astronomers have, for the first time, directly seen an exoplanet orbiting its star from one side to the other!

Here’s the incredible picture:

This makes me happy scientifically, of course, but also for personal reasons. Let me tell you a story. Two, in fact…

1) [Story the First] Beta Pic: the star, the planet, the disk

The star in question is Beta Pictoris (or just Beta Pic to its friends), a very young star — it’s only a few million years old, compared to the Sun’s advanced age of 4.56 billion — with about twice the Sun’s mass and 9 times its brightness. As stars go, Beta Pix is pretty close, just 63 light years away, and is easily bright enough to be seen with the unaided eye from the southern hemisphere.

In the above picture, taken using one of the European Southern Observatory’s ginormous 8.2 meter units of the Very Large Telescope, Beta Pic is represented by the dot in the center. The star is so bright its light swamps everything around it, so the star itself has been blocked by a piece of metal inside the camera that took the shot (that’s the reason for the dark circle in the center of the picture). This allows us to see much fainter stuff near the star.

This picture is actually a composite of three separate observations. The outer part with the blue fuzzy stuff was observed in 1996, and I’ll get back to that in a sec. The good stuff is in the center: two images of the planet, called Beta Pic b, are superposed in the picture; it was observed in 2003 (left blob), then again in late 2009 (right blob). Observations taken just months before in 2008 and 2009 observation didn’t show the blob at all — it must have been too close to the star to be seen clearly — indicating this really is a planet orbiting the star, and not just some background object like a star or galaxy. In other words, astronomers have captured the motion of the planet as it physically moved from one side of the star to the other!

Very cool. Using these observations, the orbit of the planet has been roughly estimated and is shown in the picture as well, though the tilt of it has been exaggerated for clarity. In reality, we see the orbit almost exactly edge-on. But we can see right away the orbit is not circular! The planet is clearly farther from the star on the left than on the right, meaning its orbit is pretty elliptical. In fact, it varies in distance from one billion to 2 billion kilometers from Beta Pic — roughly the distance of the Sun to Saturn and Uranus, respectively. That’s a huge variation. If this planet were in our solar system, there would be chaos as its gravity disturbed the orbits of all the outer planets.

Now, back to the weird wing-like things sticking out of either side. Those are from a 1996 observation, and what you’re seeing there is the actual disk of dust and junk from which that planet (and star) formed. Back in the 1980s, it was first determined that Beta Pic was blasting out a lot more infrared light than would be expected for its type of star. Astronomers took a better look, and found that bright disk you see in the picture. We see the disk almost exactly edge-on, so it looks like a thick, fuzzy line.

Over the years, more observations showed more detail. See how the disk is warped, bent, twisting up on the left side and down on the right? The false-colored rainbow-hued image here shows observations of the disk using my old camera STIS (bottom; on top is an earlier WFPC2 image) on board Hubble, and the bumps and wiggles in the inner disk are easy to see. That sort of thing can happen if a planet in the disk is tugging on the material as it orbits the star. Lots of other observations tantalizingly hinted at a planet buried in that mess, but unfortunately technology wasn’t up to the task of teasing out a faint planet from the bright star and disk.

But that’s changed now.

2) [Story the Second] Planets, disks, Hubble, and me

And that’s why this is such a personal story for me. When I was a kid, there were 9 planets, and that was it. In 1992 the first planets were detected around other stars, and in 1995 the first planets were detected around sun-like stars. But the disk around Beta Pic was first seen in the 1980s, when I was just starting out in college as a young astronomy major. It’s important to note that Beta Pic was the very first star to be seen surrounded by such a disk, basically confirming for the first time that stars formed from disks of material. Seeing the early pictures were fascinating, but maddening: they hinted at a planet being there, but we just didn’t have the tech to see it!

Finding a planet orbiting another star was one of the most fundamentally important and exciting goals of astronomy at the time. Every time a new image came out, we were just barely squeaking closer to that goal. I would read every new journal paper, every new popular level article that came out, and every time the conclusion was the same: we’re just a few more years away from finding other planets.

Arrrg! It was like an itch that couldn’t be scratched, except this itch was a combination of poison ivy, poison oak, and a thousand mosquito bites. Maddening!

Over the years I was tangentially involved with Beta Pic; I didn’t directly work on the rainbow STIS image of it above, but my boss Don Lindler did. I remember sitting around the office with Don and Sally Heap (the woman who made that STIS observation), talking about those images, trying to figure out how best to squeeze information and detail out of them. I also worked extensively with other astronomers who had observations of stars surrounded by disks.

Of all the work I did on Hubble, those were my favorite observations, and the ones I most enjoyed working on. I got to know them really well, like friends: AB Aurigae (pictured above), HD 163296, HD 100546, and others. These all had spectacular and beautiful disks of material swirling around them, all had the ingredients necessary to make planets. But no planets were to be seen.

That’s all changed now. We’ve seen and confirmed a planet around the grand-daddy of all these stars, Beta Pic. And, as we had hoped, the newly-discovered planet has the right location and the right mass to explain the warping of the disk. Astronomers were right all along!

And now, finally, after all those years, we’ve finally been able to scratch that itch. Ahhhhhhhhhhhhh.

Beta Pic Image credits: ESO/A.-M. Lagrange; L. Calçada. Hubble image credits: Al Schultz (CSC/STScI, and NASA), Sally Heap (GSFC/NASA); C.A. Grady (National Optical Astronomy Observatories, NASA Goddard Space Flight Center), B. Woodgate (NASA Goddard Space Flight Center), F. Bruhweiler and A. Boggess (Catholic University of America), P. Plait (hey!) and D. Lindler (ACC, Inc., Goddard Space Flight Center), M. Clampin (Space Telescope Science Institute), and NASA.

South Korea’s attempt to jump into the space race met with disaster today. A little more than two minutes after takeoff today, the nation’s Naro rocket exploded. It had been carrying a satellite, and South Korea was vying to become the tenth country to put a satellite in orbit with rockets assembled at home.

South Korea has invested more than 500 billion won (400 million dollars) and much national pride in the 140-ton Naro-1. The liquid-fuelled first stage of the rocket was made in Russia, while the second stage was built domestically, as was the satellite [AFP].

In Japan, meanwhile, happier news: Last month its space agency, JAXA, launched a batch of new missions into space that included its solar sail project, called Ikaros. Today it unfurled the sail, seen above in the blinding light of the sun.

After separating from Akatsuki [a separate probe going on to Venus], Ikaros began unfolding four panels that, when fully unfurled, should look like a square kite measuring 66 feet (20 meters) along its diagonal. Pictures sent back by a camera mounted on the spacecraft’s hub show the extension of four booms holding the panels, plus the unfurling of sail material. This is the “primary deployment” of the sail. During the secondary stage of deployment, the sail is stretched out to its full extent [MSNBC].

The sail works in two ways, as we noted in previous coverage: It can ride the physical pressure of sunlight as a sailboat rides the wind, or it can use photovoltaic cells to produce solar electricity that powers thrusters.

And another plucky spacecraft from Japan is almost home. When we last saw the damaged and travel-weary Hayabusa, which attempted to gather samples from the surface of an asteroid, it was limping home under the power of a single remaining engine and some JAXA scientists warned that it might not make it. Now things look brighter, and it could arrive back on its home planet on Sunday.

When Hayabusa (“falcon” in Japanese) reaches an altitude of 190,000 feet, its heat shield will reach temperatures of more than 5,000 degrees Fahrenheit, while the gas surrounding the capsule will reach 13,000 degrees Fahrenheit – hotter than the surface of the sun, NASA says. It is planned to fall over a large unpopulated area of Australia called the Woomera Prohibited Area [Popular Science].

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Image: JAXA

Click on the map to watch CNN's time-lapse video Now go read Nicholas Kristof's related Op-Ed in the NYTimes:
The national campaign to get President Obama to emote, throw crockery at oil executives and jump up and down in fury has failed. But here’s a long-term solution: Let’s anoint a king and queen. ....
[It] would give President Obama time to devise actual clean-up policies. He might then also be able to concentrate on eliminating absurd government policies that make these disasters more likely (such as the $75 million cap on economic damages when an oil rig is responsible for a spill). Our president is stuck with too many ceremonial duties as head of state, such as greeting ambassadors and holding tedious state dinners, that divert attention from solving problems. You can preside over America or you can address its problems, but it’s difficult to find time to do both.
Exactly. * Update: You can now vote for king and queen of America at Vanity Fair. *

Three jaw-less heads and one really old shoe. These aren’t the clues in a Law and Order episode; they’re findings from a limestone cave in Armenia. As described in a paper published yesterday in PLoS ONE, archaeologists believe they have found the world’s oldest leather shoe: it’s 5,500 years old.

“It’s pretty weird,” said lead author Ron Pinhasi to CNN regarding the disembodied heads and the placement of the well-preserved shoe. The ancient sneaker was stuffed with grass, though archaeologists can’t say whether the grass was intended as insulation or whether it helped maintain the shoe’s shape.

“We thought originally it could be a discard, but at the same time, it’s very strange, because we have only one shoe, and it’s in very good shape,” Pinhasi said. “It looks like it was more than likely deliberately placed in this way.” [CNN]

The right-footed shoe–which looks a bit like a baked potato–has some features that might entice even modern buyers: for one, its maker fashioned it from a single piece of cow leather (like a pricey pair of today’s “whole cut” footwear), and it has leather laces. It’s about a women’s size seven, but, researchers say, it might have graced a small-footed man.

The shoe was discovered by Armenian PhD student, Ms Diana Zardaryan, of the Institute of Archaeology, Armenia, in a pit that also included a broken pot and sheep’s horns. “I was amazed to find that even the shoe-laces were preserved,” she recalled. [PLos ONE release]

Scientists determined the shoe’s age by cutting two small samples of the leather and sending it to radioactive dating centers at the Oxford Radiocarbon Accelerator Unit at the University of Oxford and the University of California–Irvine Accelerator Mass Spectrometry Facility. Others have discovered older sandals–the oldest are about 7,000 to 7,500 years old and were found in the Arnold Research Cave in Missouri–but this is the oldest full shoe ever discovered.

Fashion shoe designer, Manolo Blahnik, was impressed by how much the shoe looked like today’s models. He suspects that even 5,500 years ago, wearers wanted to look chic:

“The shoe’s function was obviously to protect the foot, but I am in no doubt that a certain appearance of a shoe meant belonging to a particular tribe,” Blahnik said. “I am sure it was part of the outfit which a specific tribe wore to distinguish their identity from another.” [National Geographic]

Preservation went well beyond the modern shoebox. The limestone cave itself had relatively stable temperatures and little humidity, and the shoe was covered in layers of sheep dung.

“We thought initially that the shoe and other objects were about 600-700 years old because they were in such good condition,” Pinhasi said. “It was only when the material was dated that we realized that the shoe was older by a few hundred years than the shoes worn by Oetzi, the Iceman,” he added, referring to Europe’s oldest natural human mummy, which dates back 5,300 years. [Discovery News]

Pinhasi is now waiting, metaphorically, for the other shoe to drop: He will return to explore another nearby cave this Friday and told CNN that he believes that his team has uncovered only two percent of the area’s findings.

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Image: University of College, Cork — Media and Communications

The hack that stole the email addresses of iPad users wasn’t even a hack in the truest sense, security experts are saying today. The Goatse Security team that pulled off the feat simply overpowered bad software.

The story broke yesterday that a leak in AT&T’s security had given away the email addresses of more than 100,000 people, including some of the famous and influential who were first to adopt the tablet—Diane Sawyer, New York Mayor Mike Bloomberg, and even White House Chief of Staff Rahm Emanuel.

The specific information exposed in the breach included subscribers’ email addresses, coupled with an associated ID used to authenticate the subscriber on AT&T’s network, known as the ICC-ID. ICC-ID stands for integrated circuit card identifier and is used to identify the SIM cards that associate a mobile device with a particular subscriber [Gawker].

The Praetorian Security Group, which got a copy of the script used to grab e-mail addresses from AT&T’s servers, says that it didn’t take a sophisticated hack to steal those email address, just a brute force attack:

“There’s no hack, no infiltration, and no breach, just a really poorly-designed Web application that returns e-mail address when ICC-ID is passed to it,” Praetorian said in a late Wednesday entry on its security blog [Computer World].

Happily for the aggrieved iPad users, the stolen info included only email addresses and not credit card or social security numbers. AT&T says it has fixed the issue and will notify anyone whose address was stolen. Interestingly, though, Goatse didn’t exactly play by the rules of white hat hacking here.

The true motive behind Goatse Security exposing this information is unknown. Had the group followed generally accepted vulnerability disclosure ethics, it would have contacted AT&T directly to notify them of the flaw, and allowed AT&T a reasonable amount of time to respond to the issue before announcing the discovery. And, of course, an ethical disclosure would not include exposing the compromised data. Perhaps Goatse Security simply wanted to embarrass AT&T or Apple [PC World].

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Image: Apple