Paleontology news

This four-million-year-old fossil has taken some of the bite out of the great white shark's supposedly menacing ancestry, a new study finds.

The specimen—which includes part of the spinal column, the head, jaws lined with 222 teeth—is the most complete fossil known of an ancient great white shark.

Scientists had long assumed that great whites—which can reach lengths of 20 feet (6.1 meters)—were close kin of the prehistoric "megatooth" sharks, frightening creatures that grew up to 50 feet (15.2 meters) long and had jaws more than 9 feet (2.7 meters) wide.

But a new look at the fossil suggests that great whites are more closely related to the less fearsome and smaller mako shark, which belonged to a genus that still exists today.

If true, megatooths and great white sharks may have hit jumbo size independently, said study lead author Dana Ehret, a graduate student at the Florida Museum of Natural History.

Competition between great whites and megatooths may have contributed to both species' growth, said Ehret, whose study appears this month in the Journal of Vertebrate Paleontology.

The well-preserved specimen, found in 1988 in southwestern Peru, was donated to the Florida museum in 2008.

"It's really outstanding—not like anything we've seen in the fossil record in the past," Ehret said.

credited to news.nationalgeographic.com

A giant fossil sea monster found in the Arctic and known as "Predator X" had a bite that would make T-Rex look feeble, scientists said.

The 15-metre long Jurassic era marine reptile had a crushing 15 tonnes per square inch bite force, the Natural History Museum of Oslo University said of the new find on the Norwegian Arctic archipelago of Svalbard.

"With a skull that's more than 3 metres long you'd expect the bite to be powerful but this is off the scale," said Joern Hurum, an associate professor of vertebrate paleontology at the museum who led the international excavation in 2008.

"It's much more powerful than T-Rex," he said of the pliosaur reptile that would have been a top marine predator. Tyrannosaurus Rex was a top land carnivore among dinosaurs.

The scientists reconstructed the predator's head and estimated the force by comparing it with the similarly-shaped jaws of alligators in a park in Florida.

"The calculation is one of the largest bite forces ever calculated for any creature," the Museum said of the bite, estimated with the help of evolutionary biologist Greg Erickson from Florida State University.

Predator X's bite was more than 10 times more powerful than any modern animal and four times the bite of a T-Rex, it said of the fossil, reckoned at 147 million years old. Alligators, crocodiles and sharks all now have fearsome bites.

The teeth of the pliosaur, belonging to a new species, were 30 cms long. The scientists reconstructed the reptile from a partial skull and 20,000 fragments of skeleton.

The pliosaur, estimated to have weighed 45 tonnes, was similar to but had more massive bones than another fossil sea monster found on Svalbard in 2007, also estimated at 15 metres long and the largest pliosaur to date.

"It's not complete enough to say it's really bigger than 15 metres," Hurum said of the new fossil.

Hurum had said of the first fossil pliosaur that it was big enough to chomp on a small car. He said the bite estimates for the latest fossil forced a rethink.

"This one is more like it could crush a Hummer," he said. referring to General Motors' large sport utility vehicle.

Among other findings were that the pliosaur had a small thin brain shaped like that of a great white shark, according to scans by Patrick Druckenmiller of the University of Alaska.

Pliosaurs preyed upon squid-like animals, fish, and other marine reptiles. Predator X had four huge flippers to propel itself along, perhaps using just two at cruising speeds and the others for a burst of speed.

credited to stuff.co.nz

A new University of Florida study could help resolve a long-standing debate in shark paleontology: From which line of species did the modern great white shark evolve?

The study in the March 12 issue of the Journal of Vertebrate Paleontology falls squarely into the mako camp. It concludes megalodon and modern white sharks are much more distantly related than paleontologists initially believed.

"I think that this specimen will clarify things," said lead author Dana Ehret, a vertebrate paleontology graduate student at the Florida Museum of Natural History located on the UF campus. "When we only have isolated teeth to describe, it's very hard to come to a definitive conclusion."

The study is based on a remarkably well preserved 4- to 5-million-year-old fossil from Peru of an early white shark species: a complete jaw with 222 teeth intact and 45 vertebrae. Most ancient shark species are known only from isolated teeth. Based on tooth size and analysis of growth rings within the vertebrae, the shark was about 20 years old and 17 to 18 feet long, a size in the range of modern white sharks.

Having the teeth in place allows researchers to see important distinguishing characteristics that help determine a fossil's genus and species, such as whether a tooth curves toward the outside of the jaw or its midline, Ehret said. He believes the fossil belongs to a white shark species closely related to Isurus hastalis, a broad-toothed mako shark that probably grew to 27 feet long and lived 9 million to 10 million years ago.

An olive-grove farmer trained in fossil collection discovered it near his home in the desert of southern Peru in 1988. It now belongs to a private collection and was only recently pledged to the Florida Museum of Natural History.

"It's the only fossilized partial skull of a white shark that's ever been found," said Gordon Hubbell, the fossil's owner and study co-author.

Hubbell purchased the fossil from the farmer during his first trip to Peru, which coincidentally occurred only a few days after the discovery.

The specimen came from an area known as the Pisco Formation, famous for its rich fossil beds dating from the late Miocene to Pleistocene, about 1 million to 9 million years ago. The region was once a sheltered, shallow marine environment ideal for preserving skeletons. The formation has produced articulated broad-toothed mako shark skeletons as well as fossils of whales, aquatic sloths and sea turtles.

The study strengthens the evolutionary link between the extinct mako and the modern white shark, said vertebrate paleontologist Kenshu Shimada, an associate professor at DePaul University in Chicago. Shimada said paleontologists now need fossil skeletons from megalodon and a shark from the extinct Otodontidae family such as Otodus, a large prehistoric mackerel shark that lived about 40 million to 60 million years ago.

"If we can demonstrate the strong link between Carcharocles and Otodus from such skeletal remains," Shimada said, "we may be able to settle the evolutionary and taxonomic debates."

Megalodon was first classified in the same genus as the modern white shark in the 1840s based on the similarity of tooth shape and serrations specialized for eating marine mammals. Mako sharks have no serrations because they feed primarily on fish.

Ehret says the shark fossil's coarse serrations are evidence of a transition between broad-toothed mako sharks and modern white sharks.

"Here we have a shark that's gaining serrations," he said. "It's becoming a white shark, but it's not quite there yet."

The transition from megatooth sharks like megalodon to modern white sharks would require changes in body size and tooth serrations, thickness and enamel, Ehret said. By contrast, the transition from the broad-toothed mako shark to modern white sharks would require only the presence of serrations and a shift in the slant of a key tooth position.

credited to sciencedaily.com

A herd of young birdlike dinosaurs met their death on the muddy margins of a lake some 90 million years ago, according to a team of Chinese and American paleontologists that excavated the site in the Gobi Desert in western Inner Mongolia. The Sudden sudden death of the herd in a mud trap provides a rare snapshot of social behavior. Composed entirely of juveniles of a single species of ornithomimid dinosaur (Sinornithomimus dongi), the herd suggests that immature individuals were left to fend for themselves when adults were preoccupied with nesting or brooding.

"There were no adults or hatchlings," said Paul Sereno, professor at the University of Chicago and National Geographic Explorer-in-Residence. "These youngsters were roaming around on their own," remarked Tan Lin, from the Department of Land and Resources of Inner Mongolia.

Within an exquisite pair of the skeletons, prepared for display in Sereno's lab and airlifted back to China in late February, preserve stomach stones and the animal's' last meals are preserved.

Sereno, Tan and Zhao Xijin, professor in the Chinese Academy of Sciences, led the 2001 expedition that found the fossils. Team members also included David Varricchio of Montana State University (MSU), Jeffrey Wilson of the University of Michigan and Gabrielle Lyon of Project Exploration. The findings are published in the December 2008 issue of Acta Palaeontologica Polonica, and the work was funded by the National Geographic Society and the David and Lucile Packard Foundation.

"Finding a mired herd is exceedingly rare among living animals," said Varricchio, an assistant professor of paleontology at MSU. "The best examples are from hoofed mammals," such as water buffalo in Australia or feral horses in the American West, he said.

The first bones from the dinosaur herd were spotted by a Chinese geologist in 1978 at the base of a small hill in a desolate, windswept region of the Gobi Desert. Some 20 years later, a Sino-Japanese team excavated the first skeletons, naming the dinosaur Sinornithomimus ("Chinese bird mimic").

Sereno and associates then opened an expansive quarry, following one skeleton after another deep into the base of the hill. In sum, more than 25 individuals were excavated from the site. They range in age from one to seven years, as determined by the annual growth rings in their bones.

The team meticulously recorded the position of all of the bones and the details of the rock layers to try to understand how so many animals of the same species perished in one place. The skeletons showed similar exquisite preservation and were mostly facing the same direction, suggesting that they died together and over a short interval.

The details provided key evidence of an ancient tragedy. Two of the skeletons fell one right over the other. Although most of their skeletons lay on a flat horizontal plane, their hind legs were stuck deeply in the mud below. Only their hip bones were missing, which was likely the handiwork of a scavenger working over the meatiest part of the body bodies shortly after the animals died.

"These animals died a slow death in a mud trap, their flailing only serving to attract a nearby scavenger or predator," Sereno said. Usually, weathering, scavenging or transport of bone have long erased all direct evidence of the cause of death. The site provides some of the best evidence to date of the cause of death of a dinosaur.

Plunging marks in mud surrounding the skeletons recorded their failed attempts to escape. Varricchio said he was both excited and saddened by what the excavation revealed. "I was saddened because I knew how the animals had perished. It was a strange sensation and the only time I had felt that way at a dig," he said.

In addition to herd composition and behavior, the site also provides encyclopedic knowledge of even the tiniest bones in the skull and skeleton. "We even know the size of its eyeball," Sereno said. "Sinornithomimus is destined to become one of the best- understood dinosaurs in the world."

credited to esciencenews.com

A new dating method has found that "Peking Man" is around 200,000 years older than previously thought, suggesting he somehow adapted to the cold of a mild glacial period.

Darryl Granger, the Purdue professor of earth and atmospheric sciences who developed the dating method, co-led the study with Guanjun Shen of China's Nanjing Normal University. They analyzed four stone tools and six sediment samples from the site.

"This was the first dating of this kind to be used in an early hominid site in China," Granger said. "Many of the existing data methods rely on the availability of volcanic rock, which the Zhoukoudian site does not have. This method provides a new tool to provide insight into places where dating was previously limited."

Susan C. Antón, associate professor in the Center for the Study of Human Origins at New York University said this discovery indicates "Peking Man" was somehow behaviorally able to cope with the cold environment.

"There is evidence that Homo erectus had physically adapted to the cold, but they probably also had to be doing something in terms of behavior to handle the cold of a glacial period in northern China," she said. "There isn't good evidence of fire or any kind of skins or clothing, but evidence of such things doesn't last long and wouldn't be recorded particularly well in the archeological record. It doesn't mean they didn't have them, but we don't have a definitive answer."

Homo erectus is considered to be the ancestor species to humans and the first species that left Africa and moved into Asia. The "Peking Man" site, discovered in the late 1920s, was among the first found for Homo erectus and shaped the thoughts on the age and behavior of the species, Antón said.

Granger used aluminum-26 and beryllium-10 radioisotopic dating, which is based on radioactive decay in the mineral quartz. As cosmic rays penetrate into rocks at the Earth's surface, chemical reactions produce these isotopes of aluminum and beryllium. If the rocks are then buried, the isotopes are no longer produced and those existing begin to decay. The rate of decay can tell researchers when the rocks were deposited in a site, he said.

Granger developed the method in 1997 and first used it for geomorphology work in caves in Virginia, but he recognized it could be used at hominid sites important to understanding human evolution. A colleague in China contacted Granger and asked him to examine the Zhoukoudian site.

The Purdue Rare Isotope Measurement Laboratory, which is funded by the National Science Foundation, is one of only two laboratories in the nation with equipment capable of performing this kind of dating. The facility contains an accelerator mass spectrometer that can perform ultra-sensitive analyses to measure low levels of trace elements in a sample.

Uranium-based methods of dating had been used at the site, but it appears the results had underestimated the ages, probably due to uranium dissolved in groundwater, Granger said.

Co-authors of the paper include Guanjun Shen and Bin Gao of the College of Geographical Sciences at Nanjing Normal University and Xing Gao of the Institute of Vertebrate Paleontology and Paleoanthropology at the Academia Sinaca in Beijing.

The research team had difficulties in separating quartz from the sediment samples, and Shen and Gao got their entire department in on the work, Granger said. The sediment contained about 1 percent quartz, and the dating method requires pure white quartz.

"They ended up hand separating these bits of quartz the size of grains of sand," he said. "It took about eight hours to separate 2 grams of the pure white quartz needed, and each sample required 40 to 60 grams. Luckily the stone tools we analyzed were made only of white quartz."

Granger and Shen next plan to work on other poorly dated hominid sites in China.

This project was jointly supported by the National Natural Science Foundation of China and Wenner-Gren Foundation. The Zhoukoudian Site Museum provided the stone tools used.

credited to Purdue University (2009, March 13). 'Peking Man' Older Than Thought; Somehow Adapted To Cold. ScienceDaily. Retrieved March 16, 2009, from http://www.sciencedaily.com­ /releases/2009/03/090312165202.htm

Among the many medieval plague victims recently unearthed near Venice, Italy, one reportedly had never-before-seen evidence of an unusual affliction: being "undead."

The partial body and skull of the woman showed her jaw forced open by a brick (above)—an exorcism technique used on suspected vampires.

It's the first time that archaeological remains have been interpreted as belonging to a suspected vampire, team leader Matteo Borrini, a forensic archaeologist at the University of Florence, told National Geographic News.

Borrini has been digging up mass graves on the island of Lazzaretto Nuovo, where the "vampire" was found, since 2006.

"I was lucky. I [didn't] expect to find a vampire during my excavations," he said.

Belief in vampires was rampant in the Middle Ages, mostly because the process of decomposition was not well understood.

For instance, as the human stomach decays, it releases a dark "purge fluid." This bloodlike liquid can flow freely from a corpse's nose and mouth, so it was apparently sometimes confused with traces of vampire victims' blood.

The fluid sometimes moistened the burial shroud near the corpse's mouth enough that it sagged into the jaw, creating tears in the cloth.

Since tombs were often reopened during plagues so other victims could be added, Italian gravediggers saw these decomposing bodies with partially "eaten" shrouds, Borrini said.

Vampires were thought by some to be causes of plagues, so the superstition took root that shroud-chewing was the "magical way" that vampires spread pestilence, he said. Inserting objects—such as bricks and stones—into the mouths of alleged vampires was thought to halt the disease.

credited to news.nationalgeographic.com