Recently in Dinosaurs Category

By Agence France-Presse PARIS -- A Japanese researcher has put paleo-biologists in a flap by suggesting pterosaurs -- the winged lizards beloved of toymakers and dino movies -- were unable to fly, New Scientist says. Katsufumi Sato of the University of Tokyo carried out an unusual study on the Crozet Islands, in the southern Indian Ocean, to test flying ability among large sea birds. He attached accelerometers the size of AA batteries to the wings of 28 birds from five large species, including the wandering albatross, the world's biggest flying bird. Albatrosses fly by riding shifting winds, thanks to wings spanning 3.5 metres (11.4 feet) whose shape can be varied to exploit each draft. When there is no wind, or if the wind blows at a constant speed, the bird can only stay aloft by flapping its wings, otherwise it is forced down by gravity and air resistance. In a months-long experiment, Sato's instruments showed that the seabirds had two flapping speeds -- fast for taking off, and slow, for keeping aloft when the wind dies, New Scientist says. The bird's flapping speed is limited by its muscle strength, and the speed decreases for heavier birds that have longer wings, Sato found. According to Sato's calculations, animals heavier than 40 kilos (88 pounds) would be unable to flap fast enough to fly in zero winds. A wandering albatross is fine, as it weighs 22 kilos (44 pounds) -- but the news is pterrible for pterosaurs. Large ones would be unable to stay aloft, by this benchmark. The largest pterosaur specimen found, Quetzalcoatlus northropi, had a wingspan of 11-12 metres (35.75-39 feet) and its weight is estimated to be in the order of 100 kilos (220 pounds). Sato presented his results at a Biologging Science Symposium in Stanford University, California last month. He has run into flak from pterosaur fans who are convinced that their creatures were "dynamic soarers" like the albatross and could sustain active flight and not just glide. Differences in anatomy, physiology and environment must be taken into account when comparing the two sets of flyers, they say, according to the New Scientist report.

INQUIRER.NET executive editor Leo Magno visits The Field Museum for a close encounter with "Sue," the world's most complete Tyrannosaurus rex skeleton. Sue was named after Sue Hendrickson, the American paleontologist who discovered the skeleton.

By Richard Ingham Agence France-Presse PARIS--The extinction of the dinosaurs 65 million years ago can be traced to a collision between two monster rocks in the asteroid belt nearly 100 million years earlier, scientists report on Wednesday. The smash drove a giant sliver of rock into Earth's path, eventually causing the climate-changing impact that ended the reign of the dinosaurs and enabled the rise of mammals -- including, eventually, us. Other asteroid fragments smashed into the Moon, Venus and Mars, pocking their faces with mighty craters, the US and Czech researchers believe. Mixing skills in time travel, jigsaw-making and carbon chemistry, the trio carried out a computer simulation of the jostling among orbital rubble left from the building of the Solar System. The sleuths were guided by an intriguing clue -- a large asteroid called (298) Baptistina, which shares the same orbital track as a group of smaller rocks. Turning the clock back, the simulation found that the Baptistina bits not only fitted together, they were also remnants of a giant parent asteroid, around 170 kilometers (105 miles) across, that once cruised the innermost region of the asteroid belt. Around 160 million years ago -- the best bet in a range of 140-190 million years -- this behemoth was whacked by another giant some 60 kms (37 miles) across. From this soundless collision was born a huge cluster of rocks, including 300 bodies larger than 10 kms (six miles) and 140,000 bodies larger than one kilometer (0.6 of a mile). Over eons, the fragments found new orbits with the help of something called the Yarkovsky effect, in which thermal photons from the Sun give a tiny yet inexorable push to orbiting rocks. As the family gradually split up, a large number of chunks -- perhaps one in five of the bigger ones -- crept their way out of the asteroid belt and became ensnared by the gravitational pull of the inner planets. Around 65 million years ago, a 10-km (six mile) piece crunched into Earth, unleashing a firestorm and kicking up clouds of dust that filtered out sunlight. In this enduring winter, much vegetation was wiped out and the species that depended on them also became extinct. Only those animals that could cope with the new challenge, or could exploit an environmental niche, survived. The trace of the great event, called the Cretaceous/Tertiary Mass Extinction, can be seen today in the shape of a 180-km (112-mile) -diameter impact crater at modern-day Chicxulub, in Mexico's Yucatan peninsula. The trio of researchers -- William Bottke, David Vokrouhlicky and David Nesvorny of Southwest Research Institute in Colorado -- took their theory a stage further and checked out sediment samples from the Chicxulub site. They found traces of a mineral called carbonaceous chondrite, which is only found in a tiny minority of meteorites, as the earthly remains of plummeting asteroids are called. Most asteroids can be excluded from the Chicxulub event, but not Baptistina-era ones, they contend. Putting simulation and chemical evidence together, the team ruled out theories that a comet was to blame rather than an asteroid, and say there is a "more than 90 percent" probability that the killer rock was a refugee from the Baptistina family. The investigators also put a 70-percent probability that a four-km (2.5-mile) Baptistina asteroid hit the Moon some around 108 million years ago, forming the 85-km (52-mile) crater Tycho. The probability is lower than for Chicxulub because it is based only on a simulation. The peak of "Baptistina bombardment" was probably around 100 million years ago but is not over yet, the paper cautions. Many of the asteroids that skim dangerously close to Earth today owe their orbits to that great collision in the deep past, according to the authors. "We are in the tail end of this shower now," says Bottke. "Our simulations suggest that about 20 percent of the present-day near-Earth asteroid population can be traced back to the Baptistina family."

SO, did the T-rex taste like chicken, heh :) If you've read or watched "Jurassic Park," then you've heard the hypothesis that birds evolved from dinosaurs. But researchers now have unearthed new evidence of the evolutionary link between dinosaurs and birds. Here's an excerpt from one of the stories that came out about the Tyrannosaurus rex fossil:

When the researchers compared those amino acid sequences to those of similar proteins in several contemporary animals, they found that the T-rex sequence had similarities to those of chickens, and to a lesser extent frogs and newts. That finding bolsters a recent and controversial proposal that birds and dinosaurs are evolutionarily related, and change that hypothesis to a theory, the researchers said. "Most people believe that birds evolved from dinosaurs, but that's all based on the architecture of the bones," said John Asara, who is director of mass spectrometry at Beth Israel Deaconess Medical School. "This allows you to get the chance to say ‘Wait, they really are related because their sequences are related.' We didn't get enough sequences to definitively say that, but what sequences we got support that idea."

Meanwhile, if, like me, you've wondered how the heck T-rex could have gotten up again if it fell down, considering how itty-bitty its arms were, an expert shares the answer in Scientific American. Here's an excerpt:

It is now clear that T. rex's hands could not reach its mouth. The elbow could not be extended much beyond a 90-degree angle. The arms were very strong (perhaps capable of curling nearly 400 pounds) but had a very limited range of motion, both side-to-side and up-and-down. The wrists were considerably weaker and do not seem suited for supporting large mechanical loads. Like those of their albertosaur "cousins," the small T. rex arms were often broken during life. This fact suggests that they were poorly suited for whatever the dinosaurs were trying to use them for and, more importantly, that these animals could go without using their arms for periods of up to a month.