Finding a dinosaur's soft spots

A couple of years ago, paleontologists were stunned to find that the soft tissue of a 70 million-year-old dinosaur was preserved within a fossil from a Tyrannosaurus rex. Such a thing had never been seen before. The discovery opened the door to all sorts of speculation about reconstructing dinosaur DNA, just as it was in the fictional "Jurassic Park" tales.

Today, paleontologists are still stunned - not only to find material that looks like dinosaur cartilage, blood vessels, blood cells and bone cells, but to see the stuff in so many different specimens. "It's very scary, I guess, to find this stuff so widely distributed when nobody has ever seen it before," said North Carolina State University's Mary Schweitzer, a pioneer in the field. Although scientists don't plan to create dino-DNA anytime soon, Schweitzer and her colleagues say the growing number of tissue samples are opening the way to a scientific realm almost as exotic as Jurassic Park.

The latest installment of "Nova ScienceNow," premiering on PBS tonight, provides a taste of that new realm. The show's lead segment highlights Schweitzer's work as well as research by Ray Rogers and Kristi Curry Rogers, a husband-and-wife, geologist-and-paleontologist team at Macalester College.

For years, the Rogerses have been unearthing fossil riches in Madagascar, prime territory for paleontologists. Seventy million years ago, a killing drought was followed by torrential rains, which sent waves of mud and wet sand to cover up dead and dying dinosaurs. "You can imagine it's like a milkshake rolling down the mountain," Kristi Rogers told me.

She suspected that Madagascar's quick-preserved dinosaur remains could yield lots of promising specimens to send to Schweitzer, her longtime colleague. And she was right.

"What Mary found was exactly the same stuff that she found in the T. rex," said Rogers, whose work focuses on long-necked dinos known as titanosaurs. "It really helps show that Mary's method works. It's not just a fluke occurrence. ... It's something that's more pervasive in the fossil record."

Schweitzer, meanwhile, is making more finds in the field. She was particularly bowled over by a hadrosaur specimen her team found last year in Montana's Judith River Formation.

"What we're finding is absolutely incredible, amazing preservation," she told me today from Montana State University, the headquarters for this summer's expedition. "It's the 'freshest,' if you will, dinosaur bone that has ever had this analysis conducted on it."

By "freshest," she means that the fossil was excavated specifically for the purposes of demineralizing and analyzing its insides. Schweitzer has found that once a fossil's interior is exposed to the air, it degrades very quickly. In fact, the T. rex fossil that started it all is becoming less and less useful for soft-tissue research with the passage of time, she said.

Fortunately, the rapidly rising number of samples is giving Schweitzer hope that she and her colleagues will be able to unravel the complex biochemical story behind a dinosaur's soft spots. "We're getting specimens that have been collected specifically to do these kinds of tests, and that has never happened before," she said.

So far, Schweitzer is reluctant to say that what she's seeing are actual dinosaur blood vessels, blood cells, bone cells and bone matrix. That's what they look like under a microscope, all right, but Schweitzer is still working on the chemical analysis. "Until the chemistry is done, we can't really say at the molecular level what's going on with these," she said.

Just this year, she and other experts reported the first chemical results for T. rex collagen. The protein analysis appeared to confirm that birds are the closest living relatives of T. rex and his ilk. And that's only a start for the field of paleobiochemistry. If you take the T. rex findings, then add Rogers' titanosaurs from Madagascar ... and Schweitzer's hadrosaur ... and more samples that fossil-hunter Jack Horner is finding in Mongolia as well as Montana ... well, you can start figuring out the relationships among groups of dinosaurs, as well as the dinosaurs' links to other extinct and modern-day species, on the molecular level.

"All of these things are really creating a new world for paleontologists to inhabit," Rogers said.

That means breaking a few fossilized bones - but Rogers said more scientists are coming around to the view that the fresh scientific insights will be worth making a fresh break. "There are a number of paleontologists out there these days who realize that if you don't open that book, you'll never read the story inside," she said.

So what about dinosaur DNA? In a video from North Carolina State University, Schweitzer explained why it's unlikely anyone will be opening a real-life Jurassic Park anytime soon. Today she told me she expects to stick to proteins rather than going in search of a giant reptile's genome. Even if ancient DNA could be recovered, her lab isn't geared up to deal with it.

"You'd need a Class 3 or Class 4 or Class 5 lab, which is the same lab you'd be working with for hantavirus or Ebola," she said. (Here's a PDF file explaining the classes of biohazards.)

Schweitzer isn't ruling out the possibility that fragments of dino-DNA could someday be available. "We're not at the point where we can really say one way or the other," she told me. "I probably am not going to be the one doing the investigation. Maybe I'll have a student who's doing it."

Dinosaur lore is just one of the subjects covered on the latest "Nova ScienceNow." Here are the other topics:

• Epigenetics: Here's a strange twist in the nature-vs.-nurture debate: What you eat and how you live may actually affect the way your genes work. Chemical switches inside your cells selectively turn genes on and off, in response to substances coming into your system. That process is called epigenetics, and it appears to explain how the harm done by toxins can be passed on from mother to child, even though the mother's DNA is unaffected. Epigenetics may also explain why identical twins don't stay identical.
• Kryptos code-breaking: One of the most mysterious sculptures out there is Kryptos, a granite-and-copper monument placed in the courtyard of CIA headquarters in Virginia in 1990. The sculpture, created by James Sanborn, is covered with strings of seemingly nonsensical characters that actually stand for four coded messages. Three of the codes have been broken, yielding allusions to a buried object and the discovery of King Tut's tomb, but one has still eluded decryption. What's the solution? Em ksa t'nod!
• From Belize to black holes: "Nova ScienceNow" profiles Duke University's Arlie Petters, who is one of the world's top researchers in the field of gravitational lensing (and other subjects on the frontiers of cosmology, such as black holes and extra dimensions). Petters is a native of Belize, the Caribbean country nestled alongside Mexico, and his contributions to science education and inspiration back home are a big part of the story.

If you miss the show on TV, you can still watch it on your computer screen: All of the "Nova ScienceNow" segments will show up as video clips in the online archive on Wednesday.