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Top Ten Dinosaur and Fossil Finds: Most Viewed of 2009

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Ambrosia
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« on: December 24, 2009, 04:15:27 am »

Top Ten Dinosaur and Fossil Finds: Most Viewed of 2009
December 22, 2009

Large, "lost," or simply unusual, a bevy of prehistoric beasts were brought to life in National Geographic News's most popular paleontology stories of the year.

      10. Biggest Trilobite Sea Beasts Found ... in Swarms

The "remarkable," yard-long, horseshoe crab-like arthropods roamed in swarms of up to a thousand animals, a May study suggests.

Top ten dinosaurs and fossil discoveries picture         9. "Lost World" of Dinosaurs Survived Mass Extinction?

An isolated group of dinosaurs may have outlived their doomed relatives by as much as half a million years, an April study suggested.

Top ten dinosaurs and fossil discoveries picture         8. A Third of Dinosaur Species Never Existed?

Young dinosaurs weren't Mini-Me versions of their parents, evidence presented in October suggests—meaning that up to a third of dinosaur species may be misidentified.

Top ten dinosaurs and fossil discoveries picture         7. Tiny "T. Rex" Found —150-Pound Species Came First

No heavier than a small man, Raptorex was Mini-Me to T. rex's dinosaur Dr. Evil. But in this case, the tiny gave rise to the titanic, researchers said in September.
• See pictures

Top ten dinosaurs and fossil discoveries picture         6. Five "Oddball" Crocs Discovered, Including Dinosaur-Eater

A "saber-toothed cat in armor" and a pancake-shaped predator are among five strange, dinosaur-era crocodile cousins discovered in the Sahara, archaeologists announced in November. Meet BoarCroc, PancakeCroc, DuckCroc, RatCroc, and DogCroc.
• See pictures

Top ten dinosaurs and fossil discoveries picture         5. AUSTRALIA DINOSAUR PICTURES: 3 New Species Found

Fossils of a ferocious predator and two giant plant-eaters, named for an Aussie poet and his creations, have been unearthed in the outback, paleontologists announced in July.

Top ten dinosaurs and fossil discoveries picture         4. NEW FOSSIL PHOTOS: "Graceful Weasel," Jewel Bug, More

A long-legged mammal, a sharp-toothed rodent, and an iridescent beetle are among the more than 6,500 Eocene-epoch fossils unearthed in Germany's Messel Pit, scientists announced in August.
   

Top ten discoveries picture         3. Biggest Snake Discovered; Was Longer Than a Bus
The 60-million-year-old reptile was also heavier than a car, scientists said in February, adding that the fossil could shed light on climate change.
• See pictures

Top ten discoveries picture         2. Oldest Skeleton of Human Ancestor Found
There was never a chimp-like missing link between humans and today's apes, according to an October fossil-skeleton study that could rewrite human evolutionary history. Said one scientist, "It changes everything."
• See pictures

Top ten discoveries picture         1. "Missing Link" Found: Fossil Connects Humans, Lemurs?
The 47-million-year-old, exceptionally preserved primate fossil "Ida," unveiled on May 20, was hailed by some as a major discovery in human evolution.

The publicity frenzy made National Geographic News's brief coverage our most viewed page of the year—and inspired a backlash as some experts, including one here at Nat Geo HQ, suggested Ida was more media event than milestone.

http://news.nationalgeographic.com/news/2009/12/091222-top-ten-dinosaurs-2009-fossils.html
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Ambrosia
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« Reply #1 on: December 24, 2009, 04:20:46 am »

PHOTO: Biggest Trilobite Sea Beasts Found ... in Swarms

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Ambrosia
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« Reply #2 on: December 24, 2009, 04:21:21 am »

May 11, 2009—Talk about ruining a good beach day.

Swarms of up to a thousand giant trilobites—extinct marine arthropods such as this 35-inch-long (90-centimeter-long) fossil specimen—roamed shallow prehistoric seas, new fossils show.

The 465-million-year-old fossils, found recently in northern Portugal, are of the largest trilobites ever discovered.

The trilobites may have clustered to mate and molt—shedding old exoskeletons as new ones grew in—as well as avoid predators, scientists say.

The benefits of swarming may explain why these distant relatives of horseshoe crabs were among the most widespread arthropods of the Paleozoic era (542 to 251 million years ago).

(Related: "Horseshoe Crabs Remain Mysteries to Biologists.")

Even so, finding complete specimens bigger than 12 inches (30 centimeters) is rare—making the new find "remarkable," the study authors write in a recent edition of the journal Geology.

The critters lived at high latitudes near Gondwana—a huge southern supercontinent—and close to the South Pole during the Ordovician period (map of Earth during the Ordovician period).

This oxygen-rich, cold-water habitat may have contributed to these trilobites' gigantic sizes, the authors added.

But repeated, sudden, "lethal" influxes of oxygen-starved water may have led to the newfound trilobites' demise millions of years ago.

—Christine Dell'Amore

Photograph courtesy Artur Sá, Geological Society of America

http://news.nationalgeographic.com/news/2009/05/090511-giant-trilobites-swarms-picture.html
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« Reply #3 on: December 24, 2009, 04:22:16 am »

"Lost World" of Dinosaurs Survived Mass Extinction?
Brian Handwerk
for National Geographic News

May 1, 2009

An isolated group of dinosaurs somehow survived the catastrophic event that wiped out most of their kind some 65.5 million years ago, a new study suggests.

Dinosaurs of this "lost world," in a remote region of the U.S. West, may have outlived their doomed relatives by as much as half a million years, according to James Fassett, an emeritus scientist with the U.S. Geological Survey in Santa Fe, New Mexico.
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Ambrosia
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« Reply #4 on: December 24, 2009, 04:22:41 am »

Fassett, who has argued for years that some dinosaurs survived the mass extinction, based his latest work on fossils from the San Juan Basin in what is now Colorado and New Mexico.

There, the bones of hadrosaurs, tyrannosaurs, anklyosaurs, and several other species were found together in a sandstone formation that dates to the Paleocene epoch—the time period after the so-called Cretaceous-Tertiary (K-T) extinction event, which is thought to have killed off the dinosaurs.

As with his past research, Fassett's latest find is likely to continue sparking controversy among paleontologists.

"Every few years someone claims to have [found] Paleocene 'surviving' dinosaurs," said Hans-Dieter Sues, associate director for research and collections at the Smithsonian Institution's National Museum of Natural History.

But so far, such fossils have eventually turned out to be older remains.
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Ambrosia
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« Reply #5 on: December 24, 2009, 04:23:02 am »

"Unequivocal Evidence"

In his new study, appearing in the April 2009 issue of the journal Palaeontologia Electronica, Fassett argues that a single hadrosaur fossil helps prove that the San Juan dinos really are from the Paleocene.

After previous "survivor" finds, it was determined that the dinosaurs in question, initially entombed in sand or mud, had their bones exposed again later by natural forces such as river erosion.

The bones were then redeposited in younger rock layers, making them appear to belong to an earlier era.

But paleontologists found a concentration of 34 bones from a single hadrosaur in the San Juan Basin sandstone.

http://news.nationalgeographic.com/news/2009/05/090501-dinosaur-lost-world.html
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« Reply #6 on: December 24, 2009, 04:24:11 am »

"That's unequivocal evidence I think," Fassett said. River-washed bones would be widely scattered and also show signs of wear and tear—unlike the current fossils, some of which he describes as "pristine."

Working with colleagues at the USGS in Denver, Fassett also examined the concentrations of uranium and rare-earth metals in the fossil bones.

"I thought if we could determine the trace-element compositions of the bones, we might discover that the [older] Cretaceous bones had a different chemical fingerprint than the [younger Paleocene] bones do," he said, "and indeed that turned out to be the case."
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Ambrosia
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« Reply #7 on: December 24, 2009, 04:24:29 am »

No Reason Why Not

It's not known why some species, including crocodiles and birds, survived the K-T event while many others did not. The answer could be tied to what exactly caused the mass extinction.

The popular theory is that a killer asteroid struck the Yucatán Peninsula, although experts have argued for massive volcanism, disease, climate change, or some combination of factors.

(Related: "'Dinosaur Killer' Asteroid Only One Part of New Quadruple Whammy Theory.")

Fassett, who supports the asteroid-strike theory, said he can't explain why dinosaurs may have survived longer in some areas but not others.

"One guess is that the survivors lived in the northernmost parts of North America, at the greatest distance from the impact site, and then migrated south," he said.

"But that doesn't explain why [dinosaurs that lived later] haven't been found elsewhere. We don't have an answer for that."

Despite his caution, the Smithsonian's Sues said that the idea of Paleocene dinosaurs can't yet be dismissed.

"There is no a priori reason that dinosaurs could not have survived in some places," he wrote in an email to National Geographic News.

"Indeed, other than in the [U.S.] western interior and in Europe, we have as yet no concrete evidence when dinosaurs vanished."
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« Reply #8 on: December 24, 2009, 04:24:47 am »

http://news.nationalgeographic.com/news/2009/05/090501-dinosaur-lost-world_2.html
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« Reply #9 on: December 24, 2009, 04:25:15 am »

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« Reply #10 on: December 24, 2009, 04:25:22 am »



An isolated group of dinosaurs somehow survived the catastrophic event that wiped out most of their kind some 65.5 million years ago, an April 2009 study suggests. Above, an asteroid slams into Earth in an artist's conception of the event that is the basis for the leading theory for how the dinosaurs died.

Illustration by Don Davis/NASA
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« Reply #11 on: December 24, 2009, 04:26:49 am »

A Third of Dinosaur Species Never Existed?
Brian Handwerk
for National Geographic News
October 9, 2009


ON TV Dinosaurs Decoded, airs Sunday, October 11 at 9 p.m. ET/PT on the National Geographic Channel. Preview Dinosaurs Decoded >>

Many dinosaurs may be facing a new kind of extinction—a controversial theory suggests as many as a third of all known dinosaur species never existed in the first place.

That's because young dinosaurs didn't look like Mini-Me versions of their parents, according to new analyses by paleontologists Mark Goodwin, University of California, Berkeley, and Jack Horner, of Montana State University.

Instead, like birds and some other living animals, the juveniles went through dramatic physical changes during adulthood.

This means many fossils of young dinosaurs, including T. rex relatives, have been misidentified as unique species, the researchers argue.
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« Reply #12 on: December 24, 2009, 04:27:14 am »

How T. Rex Became a Terror

The lean and graceful Nanotyrannus is one strong example. Thought to be a smaller relative of T. rex, the supposed species is now considered by many experts to be based on a misidentified fossil of a juvenile T. rex.

The purported Nanotyrannus fossils have the look of a teenage T. rex, Horner said in the new documentary. That's because T. rex's skull changed dramatically as it grew, he said.

The skull morphed from an elongated shape to the more familiar, short snout and jaw, which could take in large quantities of food.

But the smoking gun, Horner said, was the discovery of a dinosaur between the size of an adult T. rex and Nanotyrannus.

Nanotyrannus—actually a young T. rex in Horner's view—had 17 lower-jaw teeth, and an adult T. rex had 12.

The midsize dinosaur had 14 lower-jaw teeth—suggesting that it was also a young T. rex, and that tyrannosaurs gradually traded their smaller, blade-like teeth for fewer bone-crushing grinders in adulthood.

http://news.nationalgeographic.com/news/2009/10/091009-dinosaur-species-never-existed.html
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« Reply #13 on: December 24, 2009, 04:28:20 am »

Triceratops Transformation

The paleontologists also amassed a large collection of Triceratops fossils, which had died in various stages of life, from eastern Montana's Hell Creek formation from the late Cretaceous epoch (145.5 to 65.5 million years ago).

The dinosaur skulls, which ranged from dinner plate-size to human-size, came from a range of animals.

When the paleontologists studied the skulls, they found that the youngest animals' tiny, straight horns changed as they got older: Juveniles' horns actually curved backward, whereas adult horns pointed forward.

The animal's distinctive neck frill also changed—the triangular spiked bones surrounding the frill in juveniles became flattened and lengthened into a bony fan-like shield.

"In this ten-year project we were able to collect a very good growth series that no one had ever seen before, and see this transformation that occurs," Goodwin said.

"We could document the extreme changes that occur with growth, [like] the direction that the horns are pointing."
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« Reply #14 on: December 24, 2009, 04:29:06 am »

Birds of a Feather

Clues to why dinosaurs underwent such dramatic physical changes may be found in their closest living relatives—birds experts say.

(Related: "New Feathered Dinosaur Found; Adds to Bird-Dino Theory.")

Hornbills, for example, don't sport their distinctive helmet-like head casque (see hornbill picture) until they are about three-quarters grown.

Like deer antlers, the casque helps other animals discern between mature adults and juveniles.

In the same way, dinosaurs' changing appearances might have also promoted visual communication.

For example head knobs or horns, likely paired with color variations, may have created unmistakable visual displays that made sure members of a species recognized one another.

They may also have identified dinosaurs as male or female and marked them as mate-seeking breeders or juveniles in need of protection.
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