Prepare to have your mind blown.

Certain dinosaurs—physically disparate enough that we've always thought of them as different species—may actually be the same animal at different stages of its life cycle. Also: Those big, protective-looking bone formations surrounding some dinos' heads and necks probably weren't all that useful as a defense against predators.

Case in point, triceratops. Or, maybe we should be calling it torosaurus now, I'm not sure. See, according to research done by scientists at Montana's Museum of the Rockies, the familiar triceratops is really just the juvenile form of the more-elaborately be-frilled and be-horned torosaurus.

This extreme shape-shifting was possible because the bone tissue in the frill and horns stayed immature, spongy and riddled with blood vessels, never fully hardening into solid bone as happens in most animals during early adulthood. The only modern animal known to do anything similar is the cassowary, descended from the dinosaurs, which develops a large spongy crest when its skull is about 80 per cent fully grown.

Scannella and Horner examined 29 triceratops skulls and nine torosaurus skulls, mostly from the late-Cretaceous Hell Creek formation in Montana. The triceratops skulls were between 0.5 and 2 metres long. By counting growth lines in the bones, not unlike tree rings, they have shown clearly that the skulls come from animals of different ages, from juveniles to young adults. Torosaurus fossils are much rarer, 2 to 3 metres long and, crucially, only adult specimens have ever been found. The duo say there is a clear transition from triceratops into torosaurus as the animals grow older. For example, the oldest specimens of triceratops show a marked thinning of the bone where torosaurus has holes, suggesting they are in the process of becoming fenestrated.

There are other species this might apply to, as well. Some with even bigger shifts in appearance.

While this is a Big Hairy Deal for dinosaur science, it also elicits a little bit of a "duh" moment when you go back and look at the animals in question. What you should really be getting out of this story is an illustration of how difficult it is to study a creature that's been extinct for millions of years.

After all—as my husband pointed out—nobody would be shocked to learn that a baby chick, an adult chicken, and plate of parmigiana were all the same animal. But that's because we've experienced chickens. Were an alien to drop in on Earth for one afternoon, they might be just as amazed at the life cycle of poultry as we are now at the triceratops/torosaurus'. Paleontologists are tasked with reconstructing the lives of animals nobody has ever seen alive. And that creates a world where the obvious just isn't.

New Scientist: Morph-o-saurs: How shape-shifting dinosaurs deceived us

(Via John Taylor Williams)

I went to the door to walk out and was actually turning the handle to leave, when I see this man who looked so frightened. He was holding himself as if he were wearing a straightjacket. He was backed up in a corner, protecting himself. I saw that he was studying mouths, he was studying people. Even though he was frightened, he was still watching: what is happening, what is happening?

She observed as another aide, one who couldn’t sign very well, tried to reach the frightened man. When the other assistant gave up, Schaller tried to engage the man and his true situation started to dawn on her:

I walked up to him and signed, “Hello. My name is Susan.” He tried to copy that and did a sloppy rendition of “Hello, my name is Susan.” Obviously he didn’t know what he was doing. It wasn’t language. And I was shocked.
He looked Mayan and I thought, well, if he knew Mexican sign language, he wouldn’t try to copy. That’s not a normal thing to do, even if you don’t know the language. I couldn’t walk away. I slowly figured out that this man had no language. As I said, I could see that he was very intelligent. I could see he was trying very hard. I was twenty-two years old. I had no idea of what I was doing. I was faced with how to communicate the idea of language to someone without language.

The powerful hormones in birth-control drugs change how lemurs smell, radically altering the subtle chemical cues that guide their attraction and communication.

Research on a 2-foot-tall primate shouldn’t be extrapolated directly to humans, but the findings resonate with studies in people, which have come largely from behavioral observations and are just beginning to quantify the chemistry.

“I’m not telling people not to take birth control. But what we found in lemurs needs to be studied in humans,” said Christine Drea, a Duke University reproductive biologist.

Hormone contraceptives work by tricking bodies into thinking they’re pregnant, thus preventing the release of eggs. However, these hormones are powerful. Possible side effects include sexual and romantic dysfunction. And researchers studying the broader effects of contraceptives have noticed an apparent interference with women’s taste in men.

When asked to rate the attractiveness of male odors, women are generally more attracted to men whose scents signify an immune system quite different from their own. Such a preference ostensibly leads to children with the most versatile disease defenses possible. That preference seems lessened when women take hormone contraceptives, possibly because women’s noses can’t properly calibrate if their own scent has been changed.

Men’s responses may also be scrambled. In one infamous study, men gave more money to strippers when they approached ovulation, and very little money if they were on the pill.

Such studies are compelling, but ambiguous. Does preference for certain immune-system profiles, as identified from sweat-soaked T-shirts, translate to real-world behavior? The results appear mixed. Do men really smell something, or did women dance differently? It’s hard to tell. And mate choice is just one of the animal kingdom’s many roles for scent.

Studies like Drea’s, published July 27 in the Proceedings of the Royal Society B, don’t answer all these questions, but they do add chemical detail. And Drea found that the chemical changes were even more powerful than expected.

“That a contraceptive affects fertility cues might be expected, because it changes a female’s internal hormonal state,” said Drea. “But the fact that it obliterated all the other cues contained in odors is quite remarkable.”

Drea specializes in communication among ring-tailed lemurs, 2-foot tall primates that live in large colonies, with complex social behaviors heavily mediated by scent. Drea gave injections of Medroxyprogesterone, a contraceptive marketed by Pfizer as Depo Provera, to 13 female lemurs, then analyzed their chemical secretions.

Compared to their pre-contraception state, the chemical profiles changed radically. Of the hundreds of chemicals identified, the abundance of entire classes plummeted. What had been a highly diverse assortment became relatively homogeneous, and it was much harder to chemically distinguish females from each other.

The researchers don’t know enough about individual chemicals to know their precise functions, but they’ve studied the lemurs long enough to appreciate their role not only in mate choice, but in establishing identity, relatedness and genetic health.

As for the male lemurs, they started spending less time with females after they’d been dosed. “It could be they’re showing less interest because the females are not showing immediately fertility. Or maybe the females just smelled weird,” Drea said.

Whether similar chemical fluctuations happen in people is far from certain, but the findings seem to fit with the behavioral research. They also suggest new targets for chemical monitoring.

“I’m not saying there are negative health consequences, but they could have effects on other aspects of physiology and behavior,” said Drea. “Contraception could have effects beyond those we traditionally think of.”

Image: Christine Drea.

See Also:

• Scientists Agree: It’s in His Kiss
• Pharmaceutical Love Potion: Not Yet…
• Antidepressants May Thwart Quest for True Love
• New Smell Drives Evolution of New Moth Species
• The Last Frontier: Our Stinky, Sexy Sweat

Citation: “Smelling wrong: hormonal contraception in lemurs alters critical female odour cues.” By Jeremy Chase Crawford, Marylene Boulet and Christine M. Drea. Proceedings of the Royal Society B, published online, July 27, 2010.

Brandon Keim’s Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points.