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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: Cocoon Preserves Microbe for the Ages
3 December 2012 3:00 pm
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 (left) 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 (right), a group previously unknown in the fossil record, the researchers report online today 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 (one produced by Hirudo medicinalis, the medicinal leech, inset) 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.
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*Correction, 4 December: This article has been updated to reflect that the fossil, as well as the modern-day microorganism Vorticella, is a protozoan and not a bacterium.