Science Sunday: Dinosaurs, Regrets and Sea Level Rise

Dinosaur Diversification

Dinosaurs lived for millions of years alongside non-dinosaur species without rapidly displacing them, as scientists have long thought, according to new research by paleontologists from several research institutions, including one graduate student from the University of Colorado.

The new bones, uncovered at New Mexico’s Hayden Quarry at Ghost Ranch, provide information about the evolution of the precursors to dinosaurs, how they became true dinosaurs, and then how the dinosaurs diversified.

Ghost Ranch was a popular subject for the artist Georgia O’Keefe.

According to a release on the discovery.

Dinosaurs and many other animals, including mammals, lizards, crocodiles, turtles and frogs, arose in the Late Triassic, between 235 and 200 million years ago, but it was only in the Jurassic period 200-120 million years ago that dinosaurs dominated the planet and all their predecessors vanished. Fossils of Late Triassic dinosaurs are thus rare, and until 2003, when a creature called Silesaurus was discovered in Poland, no dinosaur precursors had been found from the Late Triassic either.

At the Hayden Quarry, primary authors Randall Irmis and Sterling Nesbitt found both early dinosaurs and dinosaur precursors, not to mention bones of crocodile ancestors, fish and amphibians, all dating between 220 and 210 million years ago. The Science report also details their discovery of the leg bones (femurs) of the carnivorous Chindesaurus bryansmalli  and a close relative of the carnivorous Coelophysis, a well-known Triassic dinosaur. Both walked on two legs, reminiscent of the much later Velociraptor depicted in the 1993 film “Jurassic Park” as a cunning pack hunter.

University of Colorado grad student Daniel Woody participated in the study, which is published in this week’s Science.

I Wish I Hadn’t Written This

When you’re lamenting life’s disappointments, it makes a difference whether you’re experiencing them, or watching them happen to somebody else. Most everybody wishes they’d invested in Microsoft when it was $10, or gone to law school instead of to Ft. Lauderdale.

These regrets can have a positive side, psychologists say, but more often they just make us feel like we’ve missed the boat somewhere. But how you experience these disappointments affects how you react to them, according to new research in the June issue of Psychological Science.

Psychologists can these lamentations “counterfactual thinking.” In a series of experiments, Vittorio Girotto of the University IUAV of Venice, Italy and his colleagues attempted to demonstrate and explain the differences in counterfactual thinking between actors (those actually experiencing the problem) and readers (those who merely read about the problem).

The experiments went like this: Subjects were first divided into `actor’ and `reader’ groups. The actors were then asked to participate in a game in which they could win a reward by solving a math problem. They were then asked to choose one of two sealed envelopes: One was said to contain a difficult problem, and one supposedly contained an easy problem. In reality, both envelopes contained a problem that was nearly impossible to solve in the allotted time. Once the actors inevitably failed, they were asked to write at least one way in which things would have been better for them.

In the reader condition, subjects read a story with a protagonist who faced the same choice and ended with the same negative outcome as the subjects did in the actor condition. Like the actors, readers were required to write at least one way in which things would have been better for the protagonist.

The readers would argue to undo the protagonist’s actions, for instance to pick another envelope. Actors, however, made excuses — as the researchers so gently put it, “altered the features of the problem-solving process.” They’d say, for instance, that they could have solved the problem if they’d been allowed to use a calculator.

If I’d only studied harder for those law boards, I wouldn’t have to be telling you all this.

Glaciers and Sea Level Rise

University of Colorado researchers say that ice loss from glaciers and ice caps will contribute more to sea level rise over the coming century than the melting of the Greenland and Antarctic ice sheets.

Emeritus Professor Mark Meier of CU-Boulder’s Institute of Arctic and Alpine Research and colleagues that glaciers and ice caps are contributing about 60 percent of the worlds ice ot the oceans, and that the level has been rising over the recent decade.

Currently they are contributing 100 million cubic miles of ice a year, and the rate is increasing at about three percent annually.

Over the past 10 years, observed average sea level rise has been close to 3 mm (0.12 inches) per year.

There are three main contributions to sea level rise: thermal expansion of the oceans, plus melting of glaciers, minus the amount of water stored on land.

The estimates of observed rise and the contributions from various inputs do not quite add up. The best prior estimate for the melting glaciers is between 0.6 and 1 mm per year (0.02 to 0.04 inches). Expansion of ocean waters is estimated at 1.6 mm per year (0.06 inches). Inland water storage on land has increased by about 0.9 mm (0.04 inches) per year.

These numbers do not quite add up correctly, but scientists are uncertain about the source of the discrepancy.

There recently have been unexpected developments in the western Antarctic — floating ice shelves have collapsed, glaciers have thinned and also speeded up — potentially contributing an unanticipated jolt to increasing sea level. The western Antarctic ice sheet is smaller than the eastern one, but it contains an estimated 5 meters (16.4 feet) of sea level rise. But the interior of the East Antarctic ice sheet is growing, and may offset the sea level rise from other sources, according to a paper published in 2005.

“One reason for this study is the widely held view that the Greenland and Antarctic ice sheets will be the principal causes of sea-level rise,” said Meier, former INSTAAR director and professor in geological sciences. “But we show that it is the glaciers and ice caps, not the two large ice sheets, that will be the big players in sea rise for at least the next few generations.”

The accelerating contribution of glaciers and ice caps is due in part to rapid changes in the flow of tidewater glaciers that discharge icebergs directly into the ocean, said the study. Many tidewater glaciers are undergoing rapid thinning, stretching and retreat, which causes them to speed up and deliver increased amounts of ice into the world’s oceans, said CU-Boulder geology Professor Robert Anderson, study co-author.

The team estimated accelerating melt of glaciers and ice caps could add from 4 inches to 9.5 inches of additional sea level rise globally by 2100. This does not include the expansion of warming ocean water, which could potentially double those numbers. A one-foot sea-level rise typically causes a shoreline retreat of 100 feet or more, and about 100 million people now live within about three feet of sea level.

Novel Brain Cell Communication and Epilepsy

Epileptic seizures are classically thought of as an imbalance between the ability of the brain’s nerve cells to excite each other, on the one hand, and to inhibit each other on the other. Usually neurotransmitters bind to proteins called “receptors,” which in turn inhibits or excites the cells.

But there is another way this communication could occur, according to research that included John Rash, a professor at Colorado State University in the College of Veterinary Medicine and Biomedical Sciences. “Gap junctions” allow electric current to flow directly from one cell to another, without involving the release and diffusion of transmitter chemicals, and may be thought of as “short circuits” linking or cutting across the pathways through which cells normally communicate.

Rash runs the only laboratory in the world that can directly visualize and label the proteins in gap junctions of neurons and map their exact location in the brain.

The new research provides the first electron microscopic evidence (or “ultrastructural” evidence) for gap junctions on the axons of excitatory nerve cells in the mammalian brain. Gap junctions at this site, on axons, would be expected to act as short circuits for nerve signals and to produce “cross-talk.” The new data raise the provocative question as to whether cross-talk is an aspect of normal brain function.

What are the implications for epilepsy? First, more needs to be learned about the distribution of gap junctions – what nerve cells have them, where on the cells are they located, and how are they controlled (i.e. can the gap junctions be opened or closed by chemical signals)” Second, more needs to be learned about exactly how gap junctions contribute to the very fast brain waves that can presage a seizure. And finally, it needs to be determined if attenuating or preventing these very fast brain waves can prevent seizures. As is virtually always the case in biomedicine, each discovery creates the need for more experiments.

The research was published in the July 16 issue of the Proceedings of the National Academy of Science.


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