T. Rex 'Lived Fast and Died Young' / Another Look at Earliest Bird Ever Found / Gene Scientists Create Harder-Working Monkeys
This is SCIENCE IN THE NEWS, in VOA Special English. I'm Sarah Long. And I'm Doug Johnson. This week: T. rex as a teen-ager, and new research about a small feathered dinosaur.
Also, scientists learn how to create a harder working monkey.
And the iPod goes to college.
In the movie "Jurassic Park," T. Rex was the dinosaur that was really big and really fast. It was also really hungry for the humans who brought it back to life. At least they did for the film.
In real life, scientists have learned something new about this creature which first appeared on Earth about seventy-five million years ago. They say Tyrannosaurus rex did most of its growing in its teen-age years.
In fact, during its fastest period of growth, T. rex could gain more than two kilograms each day. The scientists say the dinosaur gained seventy percent of its final adult weight during those difficult teen years.
Gregory Erickson of Florida State University in Tallahassee led the study. He is a paleontologist, an expert in ancient remains. His research team examined fossils of seven T. rexes and thirteen other tyrannosaurs. The scientists published their report in Nature magazine.
Remains of tyrannosaurs have been found in North America and Asia. These huge animals walked on two legs. They also had two small forelegs that they used as arms. An adult T. rex was more than twenty meters long and almost four meters tall. It had about fifty teeth, each about twenty centimeters long.
The scientists counted growth circles on the dinosaur bones they examined. These rings are like those in trees. One is created for each year of life -- a kind of printed history.
But Greg Erickson points out that dinosaur growth rings are harder to read than those of trees. This is because in most cases the bone structure of the big meat-eating dinosaurs changed as they grew. The bones became hollow. So most evidence of the rings disappeared.
A few years ago, Greg Erickson was looking at bones from Sue. Sue is a famous T. rex housed at the Field Museum in Chicago, Illinois. She is the largest, oldest and most complete representative of her kind in the world.
Professor Erickson found that Sue had solid rib bones. He also noted that a leg bone and some hipbones were solid. And growth rings were present on all of them.
A number of researchers later joined him to examine these bones and compare them to other T. rex remains. They also compared the growth rings with modern reptiles like alligators and lizards.
T. rex weighed a ton at around age fourteen. At eighteen, it weighed six tons. The scientists say earlier, smaller dinosaurs had much slower growth. They says the growth rate of T. rex can be compared to that of the modern elephant. But size can come with sacrifice. John Hutchinson of the Royal Veterinary College in London says the running ability of T. rex probably decreased as the animal got bigger.
So how was it able to find enough food to get so big so fast? Peter Mackovicky of the Field Museum also took part in the study. He says T. rex at fourteen might have started to hunt slower but bigger animals. Or, he says, the dinosaurs might have traveled in groups in which the younger, faster T. rexes were the hunters.
Greg Erickson and his team also made another discovery: T. rexes apparently lived only about thirty years. In fact, they say Sue was just twenty-eight. They say her bones were in bad condition when she died, which was why scientists had thought she was close to one hundred.
Professor Erickson says the news about Tyrannosaurus rex is that it "lived fast and died young."
(MUSIC: "Only the Good Die Young"/Billy Joel)
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Several years ago, a study came out about a small dinosaur called Archaeopteryx (ar-kee-OP-tur-ix). Archaeopteryx lived in Europe almost one hundred fifty million years ago, during the Jurassic period. It had feathers and was about the size of a crow, making it the oldest bird ever found. The study said bones from the animal proved that it could fly.
Since that report, however, experts have continued to debate the flight issue. Did Archaeopteryx really fly? Now, paleontologists at the Natural History Museum in London have reported new findings in Nature magazine.
They took X-ray pictures of the structure that held the brain in the small creature. They used C.T., or computed tomography, imaging. With about one thousand images of the braincase, they were able to build their own copy of the brain.
The researchers say their model shows the Archaeopteryx brain was built like that of modern birds. It had similarly developed areas that controlled sight and movement. Also, the part of the ear that controlled balance was structured like that of birds today.
There were dinosaurs that flew before Archaeopteryx appeared. However, the only ones found did not have feathers; they were flying reptiles. Archaeopteryx has been widely seen as a link between reptiles and birds. But the new study suggests that it was more like a bird than scientists have thought.
Angela Milner led the study. She says it shows that the flight ability of Archaeopteryx was more developed than scientists have believed. She says this could mean that feathered dinosaurs flew millions of years earlier than is now thought. The only known fossils of Archaeopteryx came from a find in Germany in eighteen sixty-one.
Monkeys work hard when they know they will get something good in return. Now scientists have discovered a way to make monkeys -- and possibly humans -- into even harder workers. They temporarily suppressed a gene linked to what is known as reward learning. With the gene blocked, the monkeys lost their ability to expect a reward.
The scientists work at the National Institute of Mental Health, in the United States. Their findings appeared last week in the Proceedings of the National Academy of Sciences.
First, a team of scientists taught laboratory monkeys a computer game. This game rewarded the animals with sweet liquid. Then, the scientists injected a chemical into the brains of the monkeys. This substance temporarily blocked the gene known as D-two. That gene normally produces receiver cells for the brain chemical dopamine. Dopamine helps animals and humans experience pleasure and happiness.
Doctor Barry Richmond led the study. He says monkeys, like humans, will delay work when they know they will not get a reward. Doctor Richmond says the monkeys in the study were more or less tricked into working harder for a few months. He says they became "workaholics."
They could no longer judge how many times they had to play the computer game before they got a reward. As a result, the monkeys worked faster and made fewer mistakes.
Doctor Richmond says this study could lead to important discoveries for public health. He says the findings may be of interest in the study of mental disorders. For example, he says "people who are depressed often feel nothing is worth the work." But people with obsessive-compulsive disorder work continually. They repeat activities again and again even after they get rewarded.
Finally, an experiment at Duke University in Durham, North Carolina, might get students to work harder. Or at least more creatively. Each of the one thousand six hundred first-year students is getting an Apple iPod. An iPod is a small digital player that can hold thousands of songs. But it can also record other material, including written information.
Duke officials hope the half-million-dollar experiment will increase the creative uses of technology in education. The iPods will come with information about the school. Students will also download materials from their professors through a Web site.
SCIENCE IN THE NEWS was written by Jill Moss, Nancy Steinbach and Caty Weaver, who was also our producer. This is Sarah Long. And this is Doug Johnson. To send us a question or comment by e-mail, write to firstname.lastname@example.org. Our postal address is VOA Special English, Washington D.C., two-zero-two-three-seven, U.S.A. Join us again next week for more news about science, in Special English, on the Voice of America.