Smithsonian.com

Filed under “Hang on a sec”: a new scientific paper has called into question one of the most exciting paleontological finds of the 21st century. Soft tissue discovered deep inside a Tyrannosaurus rex legbone may be a recent “biofilm” (what you might call scunge if you found it on a dishrag), not remnants of the Toothy One after all. That’s the suggestion of a team led by Thomas Kaye, writing in the scientific journal PLOS One.

Avid Smithsoniacs and dino fans may remember bits and pieces of this story. In 2005, paleontologists Mary Schweitzer and Jack Horner were stuffing a T. rex femur inside a too-small helicopter on their way home. They cracked the bone in half to make it fit, and Schweitzer noticed a goopy residue on the 65-million-year-old insides of the bone (see the Smithsonian story). Then this April, Schweitzer and her colleagues isolated a protein called collagen from the sample, analyzed it, and found striking similarities to the collagen of modern birds.

Kaye’s contradictory opinion comes from using an electron microscope to peer at similar residues he found in different fossils. Studying fossils of 17 dinosaur and mammal species, Kaye and his team saw evidence of biofilms, or slime left behind by bacteria that grew on the bone long after the dinosaur’s death.

Where Schweitzer’s group described the remains of red blood cells, Kaye’s team thought they were seeing iron-rich structures routinely built by bacteria. (The iron content and the structures’ characteristic shape might have made them look like red blood cells in some analyses, Kaye suggested.) Kaye found these structures time and again in his samples - even in a fossilized shell, which never would have contained blood at all. Worst of all, carbon dating suggested the biofilm was as recent as 1960.

Of course, there’s still the matter of the collagen’s similarity to chickens and ostriches - a detail Schweitzer was quick to point out to reporters. And Kaye didn’t sample the T. rex in question, leaving open the chance that Schweitzer’s find was the genuine article.

Personally, I’m leaning toward believing in the extraordinary. At least until the collagen results are explained (I mean, can anyone tell me if bacteria even make collagen?) Either way, it’s fascinating to listen to the well-constructed arguments on both sides. That’s what science is all about.

You’ve still got a couple days this month to step outside, look up, and enjoy a tremendous yellow moon. One of my favorite features is that little belly-button of a crater at the bottom, called Tycho. When the moon is full, this crater and the long rays emanating from it always make me wonder if perhaps the whole orb is just a delicate paper lantern.

But if appreciating a real Moon involves too much squinting, or if the mosquitoes where you live simply won’t permit prolonged viewing, give thanks that you live in an era of unprecedented space exploration. Since last year, a Japanese probe called SELENE has been taking thousands of high-resolution images of Tycho. Now the scientists have pieced the images together into an animated video flyover of the crater in fantastic detail.

In these days of Google Earth and computer-rendered fighting pandas, it can be difficult to appreciate reality as anything more than a poor approximation of a movie. But the cliffs, plains, and pinnacles sweeping past in the video really are up there, rotating in space and baking under the glare of the Sun.

That pinprick in Tycho’s center, for example, is a mile-high mountain range complete with jagged peaks, old remains of landslides, and what looks like a totally manageable hike up one side. SELENE takes you on a 360-degree, eye-level tour and then, just as a flourish, spins out to the crater rim and zooms along the side like a NASCAR driver going into a turn.

Incidentally, the Japan Aerospace Exploration Agency’s SELENE homepage offers a refreshing and inimitably Japanese take on what a space agency’s website can look like.

(Images: Joe Huber/Wikipedia; JAXA/SELENE. Hat tip to Bad Astronomy, who is currently on something of a lunar bender owing to Apollo 11’s 40th anniversary and an actual time-lapse, color video of the moon crossing in front of the Earth).

It’s been a good week for people who look through microscopes at fossils. First off, Scientific American told us about some German scientists who discovered evidence of 400-million-year-old life trapped in seawater trapped inside volcanic rock.

Far more buzz circled around the second report: that we may be able to figure out what color dinosaurs and ancient birds were. This means that one day, paleontologist-artists may have to stop dreaming up rosy purples and outlandish greens to clothe their dinosaurs in (remember Mark Witton’s lovely pterosaurs a few posts ago?).

Is there any ephemeral detail that scientists can’t discover about long-dead creatures through clever chemistry? They’ve figured out the diet of an extinct seabird, learned about Aztec travels from records in exhumed teeth, and now they’ve put back together the stripes on a 100-million-year-old bird.

The evidence sat in front of them for years in the form of a powdery residue on some fossils. It was long thought to be the meaningless remains of carrion-eating bacteria, but Yale graduate student Jakob Vinther’s electron microscope revealed the powder looked exactly like the pigment-bearing sacs that occur on modern-day feathers. Nowadays, those sacs are full of melanin which give birds colors ranging from black to russet brown.

Though the work was done on fossil birds, the scientists report that similar residues from dinosaur scales and the hair of ancient mammals may reveal their colors as well. The researchers were also careful to point out that the residues didn’t contain any intact melanin (unlike the T. rex discovered in 2005 with actual protein still preserved inside a massive thigh). A hundred million years is a long time, after all.

(Image: J. Vinther/Yale)

Pterosaurs - those winged lizards that dotted the Jurassic skies like seagulls in a sunset - have been radically reimagined in a recent paper in the open-access journal PLOS One.

If you read the same dinosaur books as me, you probably think of pterosaurs as sort of giant, reptilian bats: rubbery-winged gargoyles that swooped low over swampy, (parrot-infested?) lagoons, snapping at fish with long, bony beaks.

But paleontologists Mark Witton and Darren Naish think this may be the wrong picture, at least for the largest pterosaurs, including the giraffe-sized Quetzalcoatlus. Its beak was too bulky and its neck too stiff for snatching fish on the wing; and its feet were too dainty to keep all that pterosaur bulk from sinking into the mud (if, as another popular guess holds, Q patrolled muddy shores like an overgrown sandpiper).

Instead, the pair thinks the creatures stalked through grasslands on all fours, snapping at smaller reptiles and insects much the way storks feed today.

The drawing above is an even bigger pterosaur called Hatzegopteryx. Other news outlets carried Witton’s drawings of Quetzalcoatlus on the wing, or snarfing baby dinosaurs. I like this drawing, though. It gives you a certain sense of… vulnerability.

Check Witton’s Flickr stream for more great art, as well as a lively retelling of how he and Naish developed their new idea. My favorite part: Witton first got the idea during lulls in his part-time job as a dishwasher:

At such times, your mind tends to wander, and you end up doing some rather strange things. Like, for instance, using your dishwater to experiment with different types of aerial predation of pelagic organisms. I did them all: skim-feeding, dip-feeding, diving…

As a former professional dishwasher, I’d just like to say: Mark, you’ve done us proud.
(Image: Mark Witton)

A study of African sediment cores suggests that ancient climate change stimulated the expansion, migration and, ultimately, evolution of early humans.

Writing in this week’s Proceedings of the National Academy of Science, the researchers say that 75,000 to 135,000 years ago, a series of “megadroughts” dried up many of Africa’s lakes and other water sources. But just 5,000 years after those droughts, the climate swung wildly, becoming much wetter.

That change to a wetter world (which, with global warming, we may again be entering) was more favorable to early humans. It fostered their migration to various parts of Africa and eventually to other parts of the world.

The theory that a changing climate helped human development is supported by a 2005 report that periods of great, rapid climate change were accompanied by increases in human brain size and complexity. Scientists theorize that the stress of adapting to a rapidly changing climate, with its altered food and water sources, forced humans to become more adaptable and find new ways to reap benefits from whatever resources were immediately available.