Now this raven-sized early bird has had its brain examined. Amy Balanoff and her colleagues from the American Museum of Natural History recently took CT scans of more than two dozen specimens, including modern birds, Archaeopteryx, and closely related non-avian dinosaurs such as tyrannosaurs, to size up the different species’ brain power.

“Bird-brained” is actually a misnomer. (Crows demonstrate this again and again.) Modern birds are distinguished from reptiles by their brains, which are enlarged compared to body size. This “hyperinflation,” most obvious in the forebrain, is important for providing the superior vision and coordination required to fly.

By stitching together the CT scans, the scientists created 3D reconstructions of the skulls’ interiors. In addition to calculating the total volume of each digital brain cast, the research team also determined the size of each brain’s major anatomical regions, including the olfactory bulbs, cerebrum, optic lobes, cerebellum, and brain stem.

The researchers found that in terms of volumetric measurements, Archaeopteryx is not in a unique transitional position between non-avian dinosaurs and modern birds. Several other non-avian dinosaurs sampled, including bird-like oviraptorosaurs and troodontids, actually had larger brains relative to body size than Archaeopteryx.

“If Archaeopteryx had a flight-ready brain, which is almost certainly the case given its morphology, then so did at least some other non-avian dinosaurs,” Balanoff says.

“Archaeopteryx has always been set up as a uniquely transitional species between feathered dinosaurs and modern birds, a halfway point,” she says. “But by studying the cranial volume of closely related dinosaurs, we learned that Archaeopteryx might not have been so special.”

If not unique, where should we place Archaeopteryx in the tree of life? More research is needed. The current study is published this week in Nature.

Image: Amy Balanoff, American Museum of Natural History

T. rex—hunter or scavenger? In this day and age of social freedoms, why not choose both? Because studying dinosaurs, especially fierce, glamorous ones like Tyrannosaurus rex, leads to fame and—well, if not fortune, then at least movie deals.

A study published this week in the Proceedings of the National Academy of Sciences determines, due to dental data, that T. rex was definitely a hunter.

In the Hell Creek Formation of South Dakota, researchers discovered a fossilized spine of a plant-eating hadrosaur that had an odd bone growth. Examining the fossil with a CT scan, the researchers found a tooth—belonging to a T. rex—within the bone. In fact, the bone had grown around the tooth.

“Lo and behold, the tooth plotted out just exactly with T. rex—the only known large theropod from the Hell Creek formation,” exclaims study author David Burnham of the University of Kansas. “We knew we had a T. rex tooth in the tail of a hadrosaur. Better yet, we knew the hadrosaur got away because the bone had begun to heal. Quite possibly it was being pursued by the T. rex when it was bitten. It was going in the right direction—away. The hadrosaur escaped by some stroke of luck.”

T. rex teeth had previously been found in the fossilized bones of a young ceratopsian (Triceratops or one of its kin), but there was no evidence to conclude whether the ceratopsian was alive or dead when the T. rex made a snack of it. The hadrosaur’s escape provides evidence that T. rex was a dangerous, if not always accurate, predator, according to the study’s authors.

Because T. rex regularly shed its teeth, the dinosaur went away hungry, but otherwise no worse for the encounter. It would have grown a new tooth to replace the one left behind in the hadrosaur’s tail. This could have been a typical example of T. rex’s hunting efforts, even if it didn’t result in a meal.

But the story doesn’t end there. Just because you hunt doesn’t mean that’s how you find all your meals, and most scientists agree that T. rex was likely an opportunistic scavenger, too. In fact, researchers and science writers that focus on dinosaurs are tired of the either-or question. “Whether or not T. rex hunted is the most-asked question I get at talks and on the radio. And that makes me sad,” tweeted Brian Switek Monday in response to this study. There are so many more exciting questions in the field, posted paleontologist John Hutchinson, in his blog response to the publication.

So we’ll put it to rest here… T. rex: hunter and scavenger.

Illustration by Robert DePalma II

Human brains vs. Neanderthal brains

German and French researchers compared CT scans of human and Neanderthals at various growth stages and published their results in Current Biology. The brains in each species started out the same size and shape, but as each grew, their shapes changed. Both begin elongated, but human brains become more round and globular. Despite having similarly large brains, according to Science Now:

The differences suggest that Neandertals did not see the world the same way we do and may not have been as adept at language or forming complex social networks.

Human brains vs Chimpanzee brains

Excitingly, the same researchers had another similar study published last Friday. Using the same scanning techniques, they compared chimp and human brains at different ages. Unlike the Neanderthals, even at birth, the brain shape is different and in fact, according to the paper, “there is no overlap between the two species throughout ontogeny.” In addition, “the shape changes associated with this early “globularization phase” are unique to humans.”

Another study published last week in PLoS Genetics explains a by-product of this brain uniqueness—a weaker immune system. It all has to do with a type of white blood cells called natural killer cells, or NK cells. NK cells are crucial in fighting disease in both chimpanzees and humans, but they do a better job in chimps— chimps are not susceptible to diseases like HIV and malaria.

Human NK cells seem to have evolved differently. NPR had a great story on the research this week.

The kind of NK cells that are good for getting lots of blood to the developing fetus are not as good for dealing with infection, and vice versa.

And whereas the chimpanzees develop the cells good for infections,

The human system, on the other hand, seems to be optimized for getting lots of blood to the developing fetus so our big brains can grow the way they’re supposed to.

More Human Brain

Finally, how about two items that are good for the brain? A study published in PLoS One yesterday shows that the video game Tetris may reduce Post-Traumatic Stress flashbacks.  And Jonah Lehrer, one of our favorite neuroscience writers, has a great blog post in Wired today about the pleasure we get from preparing our own meals.

Image from Science- Credit: (baby skulls, L) P. Gunz et al., Current Biology, 20 (9 November 2010); (Adult skulls) Philipp Gunz/MPI EVA Leipzig