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

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.”

… if Velociraptor became iconic, then its close relative Balaur should be doubly so; this newly discovered dinosaur had two sickle-shaped claws on each foot. And unlike the lithe, agile form of its cousin, Balaur was built for strength, with the build of a kickboxer rather than a sprinter.

As published yesterday in the Proceedings of the National Academy of Sciences, Balaur bondoc, which means “stocky dragon” in Romanian, is the first predatory dinosaur discovered in Europe from the Late Cretaceous period, about 65 million years ago.

According to one of the authors, Zoltán Csiki of the University of Bucharest, “Balaur is the size of an oversized turkey and unlike what we know of the large predators from other parts of the world at the same time period, like Tyrannosaurus or Carnotaurus.”

Balaur ’s oddball status actually fits its time and place. From the New York Times:

Before the end of the Cretaceous, Europe was an archipelago of islands in higher seas. Previous fossil discoveries indicated that life there followed the pattern known as the “island effect.” Animals in isolation, including plant-eating dinosaurs, often evolved as smaller, more primitive versions of their continental relatives.

In this case, Balaur was both stockier and differently structured than its mainland raptor relatives.

(Visitors to the Academy are familiar with the “island effect” which can be seen in our Islands of Evolution exhibit that displays life in the Galapagos and Madagascar. Science in Action also talks about unusual island life in “Extreme Islands.”)

Only part of the Balaur skeleton has been found, including leg, hip, backbone, arm, hand, rib, and tail bones. But that’s enough to see its extraordinary features—20 in all—including a secondarily evolved functional big toe with a large claw that can be hyper-extended, presumably used to slash prey.

“Balaur is a new breed of predatory dinosaur, very different from anything we have ever known,” says Stephen Brusatte, a graduate student at Columbia University. “Its anatomy shows that it probably hunted in a different way than its less stocky relatives. Compared to Velociraptor… it might have been able to take down larger animals than itself, as many carnivores do today.”

Balaur – a bigger, badder Velociraptor-type dinosaur?  How evolutionary!

But what would it take to satisfy the appetite of the largest terrestrial animal that ever lived? Weighing ten times more than an elephant, how did it have enough time to eat in a day?

For the first time, new research is offering a plausible answer to the question that’s long riddled paleontologists: how were giant long-neck dinosaurs even able to exist?

According to an abstract published last month in Biological Reviews, “The herbivorous sauropod dinosaurs of the Jurassic and Cretaceous periods were the largest terrestrial animals ever, surpassing the largest herbivorous mammals by an order of magnitude in body mass.”

“They were just so large that a day would have had to have 30 hours so that they were able to meet their energy demands,” explains lead author Professor Martin Sander from the University of Bonn in Germany.

So how did sauropods manage with only 24 hours? According to the study, it’s all about evolutionary efficiency. And, don’t tell your mother, but these large dinos didn’t chew their meals, they gulped.

Chewing requires time and a large head, since molars and jaw muscles have to be put somewhere. However, the herbivorous giant dinosaurs had relatively small, light skulls. This meant that sauropods were able to grow extremely long necks, allowing them to make food intake as efficient as possible. They did not constantly have to heave their 80-ton body over the Jurassic savanna while looking for their greens.

Horsetails were part of the sauropods’ diet. According to Sander and his team, they are exceptionally nutritious. But only a few animals feed off them today because presumably, horsetails are bad for the teeth. They contain a lot of silica, which acts like sandpaper.

The digestion process itself probably took several days but their stomachs were so large that they still provided them with enough energy round the clock. Moreover, the metabolism of these giant animals was incredibly powerful. They possessed amazingly sophisticated lungs, which were far more effective than those of humans.

The combination of these traits allowed the sauropods to live successfully with a “fast food” diet.

Creative Commons image by DiBgd

Found several years ago in Ethiopia, a large team of interdisciplinary scientists (including paleontologists, geologists and microbiologists) studied the amber for the past five years. It dates back 95 million years to the Cretaceous period.

It is known that dinosaurs roamed Africa during that period, but the fossils found inside the amber displayed many more diverse forms of life. The amber held fossilized ants and other insects, spiders, ferns, fungi and even bacteria. The ant finding is significant because it is one of the oldest ant fossils found and could reveal more about ant evolution. Until now, paleontologists thought ants originated in North America or South Asia (the oldest fossils had been found there), but it now seems that Africa could have been their starting point.

In addition, the amber deposit may provide fresh insights into the rise of flowering plants during the Cretaceous. “The first flowering plants appeared and diversified in the Cretaceous,” says lead author Alexander Schmidt of the University of Göttingen in Germany. “Their rise to dominance drastically changed terrestrial ecosystems, and the Ethiopian amber deposit sheds light on this time of change.”

Amber is fossilized tree resin that sometimes contains animals and plant material. The researchers do not know from which tree this amber originated. According to author Paul Nascimbene, of the Division of Invertebrate Zoology at the American Museum of Natural History, “This amber could be from an early flowering plant or a previously-unknown conifer that is quite distinct…”

Amber from the Cretaceous period is primarily found in North America and Eurasia.  This Ethiopian amber is the first major discovery of its kind from the African continent.  And the diversity of life discovered in this deposit promises to reveal new information about Africa’s evolutionary past.

Image courtesy of PNAS/ Matthias Svojtka