World's Oldest Diamonds Discovered in Australia

The world's oldest known diamonds have been found encased in a crystal in Western Australia.The minuscule gemstones are 4.25 billion years old and could provide a rare glimpse into Earth's distant geologic past.

"No one would have really predicted that diamonds were in there," said Simon Wilde, a geologist at Curtin University of Technology in Perth and a member of the team that made the find.

The discovery suggests that seas of molten lava that covered primordial Earth had cooled down faster than had previously been thought.

The find also suggests that plate tectonics, the process by which large shelves of Earth's crust move to create geologic activity, may have already been underway.

"A diamond would never form in a magma ocean," said Thorsten Geisler, a geologist at Westfalische Wilhelms-Universitaet in Munster, Germany, and another team member.

The discovery is a shocker to geologists, many of whom believed that the molten lava and volcanic activity persisted on Earth's surface for at least 500 million years after our planet formed some 4.5 billion years ago.

Diamonds Are Forever

The tiny diamonds were found trapped in zircon, a rare and exceptionally stable mineral that forms under temperatures between 1,112 and 1,652 Fahrenheit (600 and 900 degrees Celsius).

Once zircon has crystallized it may be moved around by geological processes, but its chemical makeup and structure don't change. This makes its age easy to pinpoint.

Zircon crystals represent the only record of the first 400 million to 500 million years of Earth's history, Wilde explained.

By analyzing a crystal's trace minerals and structure, geologists can deduce the conditions under which it formed.

John Valley, a geologist at University of Wisconsin in Madison who was not involved in this study, notes that there are four known "recipes" that create diamonds.

But the 4.25-billion-year-old diamonds "suggest the additional possibility that the diamonds have formed by some process that is not yet understood."

Study co-author Wilde said, "The bottom line is that we really honestly don't know why they're there."

The study, led by Martina Menneken, a master's student at the Westfaelische Wilhelms-Universitaet, appears in this week's issue of the journal Nature. Alexander Nemchin from Curtin University of Technology also contributed.

Clues to Earth's Earliest Life?

One exciting prospect is that if Earth cooled down earlier in its existence, then it's possible that life on Earth cropped up earlier too, Geisler said.

(Related: "Weird Australia Rocks Are Earliest Signs of Life, Study Says" [June 7, 2006].)

Geisler hopes that analyzing the various types of carbon in these diamonds could reveal whether this was the case.

"We don't know yet, but this is potential information contained in the carbon," he said.

Valley, the Wisconsin geologist, added, "Even though these diamonds are too small to be of commercial value as gems, scientists will find them even more valuable for the information they carry about the Earth."

The Nobel Exception

The Nobel Prize is a lot more than a medal.Winners get $1.4million and the world's best resume line.Here's another thing to life under"life's nor fair":Nobel winners also live longer.New research from the University of Warwick says that academics who get the fateful phone call from Sweden stick around about two years longer than colleagues who don't make the final list.The effect mirrors what's been seen before in Oscar winners,whose life spans grow with every statue they take home.Since only four people have ever won multiple Nobels,though-and one,Marie Curie,had a short life because of her prizewinning work on dangerous radiation-the researchers couldn't document a truly identical trend.Still,they were able to figure out that,as with Oscars,it wasn't the cash that did the trick.Apparently,the key to long life among Nobel laureates was simply having the bragging rights.
The research has some lessons for mere mortals,too：it throws new light on an ongoing argument about why people of high social status tend to live longer,regardless of how much health care they get.One theory holds that winners-of prizes,but also in the game of life-are so buoyed by their achievements that their brains are"buffeted against any subsequent adversities",says the University of Toronto's Donald Redelmier,who studies the Oscar phenomenon,In other words,stress doesn't bother there folks as much.Redelmeier's won explanation?After you're reached the pinnacle,you'd be quite disinclined to be seen drunk in public if you've got a Nobel Prize,"he says.Unless,of course,you're tipsy from a little celebratory champagne of,for that matter,a toast to your longevity.

Jaws, Teeth of Earliest Bony Fish Discovered

Fossils of sardine-size fish that swam in ancient oceans are the earliest examples of vertebrates with teeth that grow from their jawbones, according to new a new study.

The fish, which lived 420 million years ago, are a "very modest" beginning for the jaw-and-tooth pattern widespread in nature today, said study co-author Philippe Janvier, a paleontologist at the National Museum of Natural History in Paris, France..
"It's really the first evidence that we have of the earliest bony fishes—the earliest ancestors of all the fishes that have the[ir] bones and teeth implanted in the bones of the jaw," Janvier said.

Modern bony fish such as cod, herring, and coelacanths have this tooth arrangement. So do tetrapods—four-limbed creatures such as frogs, crocodiles, and humans, which are all descendants of bony fishes.

When a bony fish or a tetrapod loses a tooth, a new one grows from the bone below the void, whereas other jawed vertebrates, such as sharks, have teeth that grow from inside their gums. Sharks have skeletons of cartilage instead of bone.

Shark teeth are lined up in "families." New teeth grow at the inner end of their respective tooth family, and old teeth fall off at the end of an inside-out progression—similar to a conveyor belt.

Though fossil representatives of the earliest members of each of these living groups are well known, the earliest stages of jawed vertebrate evolution presents a fuzzier picture.

The new fossils help clarify these questions, Janvier said.

Transition Fossils

The researchers discovered the telltale bony fish fossils among fragments collected on the Swedish island of Gotland in the Baltic Sea. Other fragments came from boulders carried to Germany by glaciers a few million years ago.

Some of the fossils belong to the species Andreolepis hedei and others to Lophosteus superbus, fish previously identified by scale and head bone specimens.

Whether they were truly bony fish or more like sharks was an open question, however.
Two of the new fossils suggest a direct link to bony fish: tooth-bearing jawbones.

What's more, the bones show a tooth pattern that is in between the tooth rows of sharks and bony fishes.
Though these ancient bony fish teeth grew from a bone, old teeth remained attached to the bone. New, larger teeth grew at the inner end of each tooth file.

"It shows a sort of transition between the shark condition and the bony fish condition," Janvier said.
Within 20 million years after Andreolepis hedei and Lophosteus superbus lived, the first bony fish with much larger teeth characteristic of modern bony fish and tetrapods appear in the fossil record. This was during the Devonian period, 416 to 359 million years ago.
"That's very important because it allowed the bony fishes to become predators," Janvier said.

Sharks also existed in the Devonian, but they were "humble compared to the bony fishes," he said.

The first bony fishes probably ruled the seas, rather than sharks, because the bony fishes' teeth lasted a longer time in the jaw.

"Then, later on, the sharks ... became much larger and big predators," Janvier added.

The study appears in tomorrow's issue of the journal Nature.

Sorting Characteristics

Michael Coates, a biologist at the University of Chicago in Illinois who studies early vertebrate evolution, was not part of the research team.

He said the discovery of rare fossils like the ancient bony fish allows scientists to sort general, primitive characteristics of all jawed vertebrates from the more specialized features that distinguish sharks from bony fishes.

The new study, he noted, clearly shows that Andreolepis and Lophosteus are bony fishes, but their tooth pattern raises a question about what makes a shark a shark.

"Growing teeth in this serial manner around the jaw margin—which once upon a time looked like it was unique to sharks—now looks like it is a general system."