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

This conclusion overturns the conventional wisdom that dinosaurs stayed active by day while early mammals scurried around at night. “It was a surprise, but it makes sense,” co-author Ryosuke Motani said.

Motani’s research focused on the scleral ring. Dinosaurs, lizards, and birds all have a bony ring in their eye, called the scleral ring (a structure not found in mammals or crocodiles). The researchers measured the inner and outer dimensions of this ring, plus the size of the eye socket, in 33 fossils of dinosaurs, ancestral birds, and pterosaurs. They took the same measurements in 164 living species.

In living species, diurnal animals have a small opening in the middle of the ring. In nocturnal animals, the opening is much larger. Cathemeral animals—active both day and night—tend to possess a scleral ring opening somewhat in between.

By looking at the living species, the UC Davis team confirmed that eye measurements accurately predict whether animals are active by day, by night, or around the clock. They then applied the technique to fossils from herbivorous and carnivorous dinosaurs, flying reptiles called pterosaurs, and ancestral birds.

The measurements revealed that the big plant-eating dinosaurs were active day and night, probably because they had to eat most of the time, except for the hottest hours of the day when they needed to avoid overheating. Modern megaherbivores such as elephants show the same activity pattern, Motani said.

Velociraptors and other small carnivores hunted at night. Flying creatures, including early birds and most pterosaurs, probably flew around in the daytime.

Nature News and Discover mention that this discovery could put the famous fossil of a Velociraptor battling Protoceratops in a new light. From Nature News:

…it provides even more information, suggesting that Velociraptor, a nocturnal predator, came upon the Protoceratops while it was resting at night.

Talk about a midnight snack!

Image courtesy of Kabacchi/Wikimedia

… 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!