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

What’s in a nose—er, I mean, a name? For the newly described dinosaur, Nasutoceratops titusi, a great, big, honking lot!

Nasutoceratops means “big-nose horned face” and indeed this Triceratops relative is mostly nose. Having a “Jimmy Durante profile,” claims National Geographic’s Phenomena blog. And ScienceNOW says, “Does it sometimes seem that dinosaurs were competing with each other to see who could look the wackiest?”

Behind that nose is a familiar-looking dinosaur, with a huge skull bearing a single horn over the nose, one horn over each eye, and an elongate, bony frill at the rear, like other ceratopsids.

Unearthed in Grand Staircase-Escalante National Monument in southern Utah, the huge plant-eater inhabited swampy Laramidia, a landmass formed when a shallow sea flooded the central region of North America, isolating the western and eastern portions of the continent for millions of years during the Late Cretaceous Period.

“Nasutoceratops is one of a recent landslide of ceratopsid discoveries, which together have established these giant plant-eaters as the most diverse dinosaur group on Laramidia,” says Andrew Farke of the Raymond M. Alf Museum of Paleontology.

And while other ceratopsid fossils in Laramidia have raised questions about whether the specimens represent separate species or instead illustrate the differences between the juveniles and adults of a single species (see our video on that topic), Nasutoceratops titusi is not just a separate species, it’s from an entirely different group (read this article in Nature News to learn more).

So why the distinctive nose? Even scientists can’t sniff this one out. “The jumbo-sized schnoz of Nasutoceratops likely had nothing to do with a heightened sense of smell—since olfactory receptors occur further back in the head, adjacent to the brain—and the function of this bizarre feature remains uncertain,” according to Scott Sampson of the Denver Museum of Nature & Science.

The findings are published this week in the Proceedings of the Royal Society B.

Image by Lukas Panzarin

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

When large bullies disappear, the formerly bullied thrive.

That’s especially true in mass extinction events, when smaller animals have a chance if the larger, more competitive animals go away. Take the largest extinction event on Earth, the end-Permian extinction, 252 million years ago. Ninety percent of life on the planet was basically wiped out.

Scientists previously believed that gentler creatures didn’t thrive after that extinction event, but a new study, in this week’s Proceedings of the National Academy of Sciences, says that dinosaur predecessors did in fact succeed and even diversify.

The new insights come from seven fossil-hunting expeditions since 2003 in Tanzania, Zambia, and Antarctica, along with work combing through existing fossil collections. The team used the fossils to create two views of four legged-animals in what was at the time southern Pangaea. The first view is of 5 million years before the extinction event and the second is 10 million years after the event.

The study found that before the extinction event 35 percent of four-legged species were found in two or more of the five areas studied, with some species having ranges that stretched 1,600 miles. But according to the authors, ten million years after the extinction event, the quadrupeds showed clear clear geographic clustering and just 7 percent of species were found in two or more regions.

The smaller distribution of four-legged animals, like the Asilisaurus, pictured above, suggests that they had less competition and didn’t have to move too far to find food or suitable habitats. It also reveals that the animals were so successful, they were able to diversify.

Good riddance, bullies! “Groups that did well before the extinction didn’t necessarily do well afterward,” says lead author Christian Sidor, of the University of Washington. “What we call evolutionary incumbency was fundamentally reset.”

Image: Marlene Donnelly/Field Museum of Natural History

If geochronology is “the science of determining the ages of earth materials” (according to the center’s website), then Renne must know his gnat’s eyebrow. For those of us lay-folk, it’s about 5,000 years.

Renne and his colleagues have a new paper in Science pinpointing the dates of both the impact and the dinosaur extinction, placing them within the same time of each other—providing evidence, once again, for an asteroid or comet impact being the cause of extinction.

The 110 mile-wide Chicxulub (cheek’-she-loob) crater, off the Yucatan coast of Mexico, is likely the result of a six-mile in diameter asteroid or comet. Using and refining a technique called argon-argon dating, the scientists determined that the impact occurred 66,038,000 years ago, plus or minus 11,000 years.

The same argon-argon dating put the dinosaur extinction at 66,043,000 years ago, with the same margin of error.

The first link between the impact event and dinosaur extinction was published in 1980 by UC Berkeley’s Luis and Walter Alvarez. Since then, many other scientists have supported or refuted the theory, sometimes putting the extinction several hundred thousand years before the impact.

“When I got started in the field, the error bars on these events were plus or minus a million years,” says UC Berkeley paleontologist William Clemens. “It’s an exciting time right now, a lot of which we can attribute to the work that Paul and his colleagues are doing in refining the precision of the time scale with which we work.”

Despite the synchronous impact and extinction, Renne cautions that the impact was not the sole cause of extinction. Dramatic climate variation over the previous million years, including long cold snaps amidst a general Cretaceous hothouse environment, probably brought many creatures to the brink of extinction, and the impact kicked them over the edge.

“These precursory phenomena made the global ecosystem much more sensitive to even relatively small triggers, so that what otherwise might have been a fairly minor effect shifted the ecosystem into a new state,” Renne says. “The impact was the coup de grace.”

This isn’t just a question heard on the playground; it’s asked by scientists as well. Though many agree that the mountain-sized asteroid (that left the now-buried Chicxulub impact crater on the coast of Mexico’s Yucatan Peninsula) ultimately caused the mass extinction, some scientists continue to argue about the health of dinosaurs before the event.

A new study this week, published in the Proceedings of the National Academy of Sciences looks at the health of ecosystems from 13 million to 2 million years prior to the impact. The Academy’s Peter Roopnarine and his colleagues constructed food webs to examine the communities that lived in North America at the time.

In fact, Peter has spent the past eight years constructing paleo food webs, looking comprehensively at who lived in a particular place at a particular time, what they ate and who ate them. It’s a great way to see into the past.

Constructing these food webs involves looking at the fossil record—bone damage, stomach contents, etc.—and creating computer models. Peter says this involves a lot of data. He finds ecologically similar species that occupied a similar space and time and likely shared the same predators and prey. He starts by creating links between them and then builds from there.

Peter also looks at the present to reconstruct the past. He looks at how predators and prey are distributed in a modern ecosystem—there will only be so many top predators, for example, yet there will be many organisms at the bottom of the food web. Peter says that modern food webs are dominated by specialists—those that just eat a few organisms. But as you follow along, you’ll find a few generalists that consume an assortment of items.

Like a baseball statistician looking to build a new team, Peter uses these numbers and statistics from current players to input into his model to map past scenarios.

But, of course, the food web he models represents just one possibility of how that ecosystem looked at that time. So Peter runs the model thousands of times to get the average picture of the dynamics of the food web.

Now back to the dinosaurs… Running the food webs for 13 million years before the impact, Peter and his colleagues found that the ecosystems had been changing in North America. There was less diversity of species with lots of smaller vertebrates and very, very large herbivores. These changes could have taken place when the interior western seaway dried up, which would have affected climate and vegetation.

This doesn’t mean that the ecosystems were fragile by any means. Peter says. They were fine, robust even. Perhaps just a little less robust closer to the impact.

But when the impact hit, these small differences played a significant role, Peter explains. The ecosystems were a bit more vulnerable. “It was a bad time to be alive.”

“Our study suggests that the severity of the mass extinction in North America was greater because of the ecological structure of communities at the time,” notes Peter’s colleague and lead author of the paper Jonathan Mitchell of the University of Chicago.

And these small changes in the past can help us learn what might happen in future major events, says Peter. “What do extreme occurrences look like, where is our vulnerability, what does a recovery look like? Besides shedding light on this ancient extinction, our findings imply that seemingly innocuous changes to ecosystems caused by humans might reduce the ecosystems’ abilities to withstand unexpected disturbances.”

Pegomastax was a heterodontosaur, a genus of herbivores that lived when the supercontinent Pangaea had just begun to split into northern and southern landmasses. The single specimen of the new species was originally chipped out of red rock in southern Africa in the 1960s and discovered in a collection of fossils at Harvard University by Sereno decades ago, but only described now. (In an article in the New York Times, he describes how apologetic he is for not getting to it sooner.)

It’s name means “thick jaw from Africa,” which describes the cat-sized species well. Pegomastax had a short parrot-shaped beak up front, a pair of stabbing canines, and tall teeth tucked behind for slicing plants. The tall teeth in upper and lower jaws operated like self-sharpening scissors, with shearing wear facets that slid past one another when the jaws closed. The parrot-shaped skull, less than three inches long, may have been adapted to plucking fruit.

The canine teeth in heterodontosaurs often lead scientists to believe that these small dinosaurs ate meat or at least insects, but Sereno says they were more likely used in self-defense and competitive sparring for mates.

Another bizarre feature of Pegomastax are the porcupine-like bristles that likely covered its entire body. Sereno imagines these heterodontosaurs scampering around in search of suitable plants, looking something like a “nimble two-legged porcupine.”

A nimble two-legged porcupine that nips? As a pet? No, thanks.

Image: Tyler Keillor

A team of scientists, led by Ryan M. Carney at Brown University, have now taken that first Archaeopteryx fossil and analyzed the famous dinosaur-bird’s color and flight abilities.

A few years ago, some of the same scientists found a way to determine the color of feathered dinosaurs by looking at melansomes in fossils. As Carl Zimmer describes in his Discover blog:

Depending on the size, shape, and spacing of melanosomes, they can produce a range of hues. It turns out that melanosomes are incredibly rugged, sometimes enduring for millions of years.

(Science in Action covered this research here.)

Placing the fossil in a powerful type of scanning electron microscope, Carney and his colleagues measured the length and width of the Archaeopteryx’s sausage-shaped melanosomes, roughly 1 micron long and 250 nanometers wide. To determine the melanosomes’ color, the team compared the Archaeopteryx melanosomes with those found in 87 species of living birds, representing four classes: black, gray, brown, and a type found in penguins. “What we found was that the feather was predicted to be black with 95 percent certainty,” Carney says.

Next, the team sought to define the melanosomes’ structure with greater accuracy. For that, they examined the fossilized barbules—tiny, rib-like appendages that overlap and interlock like zippers to give a feather rigidity and strength. The barbules and the alignment of melanosomes within them, Carney said, are identical to those found in modern birds.

“If Archaeopteryx was flapping or gliding, the presence of melanosomes would have given the feathers additional structural support,” explains Carney. “This would have been advantageous during this early evolutionary stage of dinosaur flight… We can’t say it’s proof that Archaeopteryx was a flier. But what we can say is that in modern bird feathers, these melanosomes provide additional strength and resistance to abrasion from flight, which is why wing feathers and their tips are the most likely areas to be pigmented.”

The research was published today in Nature Communication.

Illustration: NobuTamura

ScienceNOW reports that:

Tails are often an enigma; many creatures have them, but scientists know little about their function, particularly for extinct species. Dinosaur tails are no exception. Researchers have speculated that some species’ tails were used in fighting, whereas others for stability.

Our friend Robert Full and his colleagues at UC Berkeley found how when leaping, red-headed African Agama lizards swing their tails upward to prevent them from pitching head-over-heels into a rock. You can see a video of this feat here.

“We showed for the first time that lizards swing their tail up or down to counteract the rotation of their body, keeping them stable,” says Full. “Inspiration from lizard tails will likely lead to far more agile search-and-rescue robots, as well as ones having greater capability to more rapidly detect chemical, biological or nuclear hazards.”

While Full is a biology professor, he is no stranger to robots, Scientific American reports.

These are just the latest developments in Full’s full-on flirtations with robots. He has worked with engineers since the mid-1990s when he helped to develop the crab-inspired Ariel, a minesweeping robot… that can look for buried explosives in surf zones. In 2008 Full co-founded the Center for Integrative Biomechanics in Education & Research (CiBER) at University of California, Berkeley, to further integrate the work of biologists and engineers when designing technology.

“Engineers quickly understood the value of a tail,” UC Berkeley engineering graduate student Thomas Libby explains. “Robots are not nearly as agile as animals, so anything that can make a robot more stable is an advancement, which is why this work is so exciting.”

Full and his team received a surprise benefit from the lizard tail research: understanding how dinosaur tails function.  The new research tested a 40-year-old hypothesis that the two-legged theropod dinosaurs—the ancestors of birds—used their tails as stabilizers while running or dodging obstacles or predators.

Indeed, just like the velociraptor depicted in the movie Jurassic Park, these agile dinosaurs may also have used their tails as stabilizers to prevent forward pitch, Full says. “Muscles willing, the dinosaur could be even more effective with a swing of its tail in controlling body attitude than the lizards.”

The research is published in the recent edition of Nature.

Image: Robert Full lab, UC Berkeley

Ok. No more movie voice. But where did the large sauropod Camarasaurus roam? A new paper in Nature may be closer to discovering the truth.

Scientists believe that some dinosaurs migrated seasonally for food, and now Henry Fricke and his colleagues at Colorado College may have the evidence—thirty-two Camarasaurus teeth.

Camarasaurus were enormous. With an average length of 50 feet, they ate about twice as much as today’s modern elephants—almost 1,000 pounds of food each day! As Fricke told Nature News,

They are huge—they would probably have eaten themselves out of house and home if they stayed in one place.

According to the fossil record, Camarasaurus inhabited the dry plains of western North America. The teeth the researchers sampled were all found in Wyoming and Utah, where the ancient seasonality record is pretty clear. ScienceNOW explains:

During the wet season, the prehistoric lowland basins of Wyoming and eastern Utah were flat, open habitats carpeted with ferns and stands of conifers. The researchers propose that the dinosaurs left this area at some point during the year, probably during the dry season, when the smorgasbord of tasty plants closed.

How did the researchers extract the evidence of movement from the Camarasaurus teeth? By measuring the ratio of isotopes within the enamel, New Scientist explains.

The ratio of isotopes is determined by the water the dinosaurs drank. [Fricke] found the ratio in teeth was different to that in carbonate rock from the floodplain—which carries the signature of the water it formed in. This suggests that Camarasaurus sometimes left the area.

Fricke and his team suspect the dinosaurs headed to higher, wetter ground seasonally, when the plains were dry, possibly traveling up to 180 miles.

The team plans to sample the teeth of other dinosaur species next. They have a hunch that where the herbivores traveled, the carnivores were close behind.

Image credit: Dmitry Bogdanov/Wikipedia