
Call it extraterrestrial bling. Fossilised sea creatures have been found that coated themselves in tiny diamonds created in the asteroid impact that killed off the dinosaurs.
The fossils were discovered by a team led by Michael Kaminski, a geologist at University College London. They went to the Umbria-Marche basin of eastern Italy in search of the fossilised remains of deep-ocean creatures called agglutinated foraminifera. These amoeba-like single-celled organisms build protective "tests" around themselves by sticking together sediment grains from the sea floor. Curiously, they seem to prefer heavy grains, presumably to help them sink to the bottom of the ocean.
Kaminski's team looked for fossils in rock samples taken just above and below the sediment layer created by the huge asteroid impact at the end of the Cretaceous period, 65 million years ago. The foraminifera tests they found were mainly composed of common minerals such as quartz, but some of the component grains were unusually rich in metals such as nickel and cobalt, indicating that they had originated in outer space.
Even more surprising were microscopic granules of carbon, no more than 10 micrometres across, which were subsequently identified as diamonds. "The foraminifera were deliberately using extraterrestrial diamonds in their shells," says Kaminski.
The majority of these microdiamonds were formed from terrestrial graphite rock that was altered by the extreme pressure and temperature of the asteroid impact, but a small proportion was truly extraterrestrial, derived from carbon in the asteroid itself.
It seems the main reason the foraminifera chose grains containing diamonds and metals for their tests was the lack of other grains of a similar density at this particular site. What remains a mystery is how these ancient foraminifera were able to pick out the densest grains, an ability they share with their latter-day descendants (pictured).
Kaminski's results were published last month in the Proceedings of the Seventh International Workshop on Agglutinated Foraminifera.
Comets and Asteroids - Learn more about the threat to human civilisation in our special report.
By Cap'n Zapp Brannigan Fgs Mrsc
Thu May 08 12:22:14 BST 2008
Why not just sea creatures that covered themselves in diamonds after an asteroid impact.By Whipster
Thu May 08 15:27:42 BST 2008
Alright yeah... But at least it's the strongest and most plausible theory. Whether other events contributed or not, their effects were just propagated down from the most significant event.By Bootyluva69
Fri May 09 02:58:05 BST 2008
This comment has been found to be in breach of our terms of use and has been removed.By Bootyluva68
Fri May 16 02:29:54 BST 2008
This comment has been found to be in breach of our terms of use and has been removed.By George
Thu May 08 18:03:16 BST 2008
How on earth can microfauna incorporate diamonds into their shells ? That implies they have intelligence, and are able to understand that diamonds are expensive.By Fashion Is Older Than Man
Thu May 08 19:50:35 BST 2008
It also implies that wearing diamonds was already very fashionable 65 million years ago. And not just any diamond, but the extraterrestrial kind! I bet in the market at Antwerp they'll tell you those are definitely the most expensive.By Wes
Fri May 09 16:55:23 BST 2008
Careful by George!By John
Sat May 10 23:46:17 BST 2008
I loved your remark about it not being a proven fact,as if that work of fiction and fable were in any way true.divine breath,in the four hundred years after jebus death, a so many remarks to ridicule but why bother when your doing such a good job yourself. Quick question if you don't mind,how many angels can you fit on the end of a pin?By John A W Lock
Fri May 09 11:08:03 BST 2008
How are foraminifera preserved? Answer: they sink to the bottom. What if only the heavier foraminifera sank straight to the bottom and the lighter ones remain in suspension or settle elsewhere? Or that foraminifera are graded by gentle currents after initial deposition?All comments should respect the New Scientist House Rules. If you think a particular comment breaks these rules then please use the "Report" link in that comment to report it to us.
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10:45 10 October 2008