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Interesting gullies observed on Vesta

Scientists are puzzling over the discovery of gullies inside young craters on the giant asteroid Vesta.

NASA’s Dawn spacecraft spied two types of channels on the crater walls of the second-largest object in the asteroid belt. The first kind – short and straight – were likely carved by dry material flowing down the depression.

But researchers are stumped by the appearance of long and narrow gullies. Such features are sculpted by water on Earth, but how they occurred on Vesta is not yet known.

The new images were released at a meeting of the American Geophysical Union in San Francisco.

Dawn departed from Vesta in September and is headed toward Ceres, the asteroid belt’s biggest object. It is scheduled to arrive in 2015.

– Associated Press

Cocoons preserve ancient fossils

Cocoons don’t just protect developing eggs and larvae; they can also preserve fossils for hundreds of millions of years.

Scientists have discovered a 25-micrometer-long, teardrop-shaped protozoan trapped in the wall of an egg case produced by a leech between 200 million and 215 million years ago. The Triassic-era relic’s coiled stalk and large, horseshoe-shaped nucleus make it an ancient doppelgänger of the modern-day Vorticella, a group previously unknown in the fossil record, the researchers report online this month in the Proceedings of the National Academy of Sciences.

As soft-bodied organisms, protozoans aren’t typically preserved as fossils. But egg cases – the walls of which quickly harden from a protein-and-sugar-rich mucus secreted by the invertebrates – of leeches and their kin are surprisingly common, the researchers explain. Like amber, which starts out sticky and then hardens, the tiny egg cases can trap and then preserve soft-bodied organisms that would otherwise be quickly lost to decomposition.

Although a few teams have previously described small fossils, such as spores and microorganisms entombed in such egg cases, the cocoons have largely been ignored by paleontologists and could therefore serve as an unrecognized yet bountiful source of microbial fossils.