Paleontology news

The platypus tops many people’s oddest mammal list, what with its ducklike bill and beaverlike tail. Its closest relatives, the echidnas, don’t get the press the platypus gets, but they are pretty weird, too, and are the only other monotremes, or egg-laying mammals, around.

Now Timothy Rowe of the University of Texas and colleagues report in The Proceedings of the National Academy of Sciences that the divergence may have occurred long before that. They used X-ray computer tomography to examine a 120-million-year-old fossil, Teinolophus trusleri. It is an ancestral platypus, they say, with some similar morphological features, in particular a canal in the jaw that the researchers say is evidence that Teinolophus had a duckbill.

The researchers conclude that the platypus and echidna branches of monotremes were already distinct at that early date. The findings also suggest that monotremes diversified at a slower rate than the other mammals.

credited to nytimes.com

A fossil of a primitive feathered dinosaur uncovered in China is helping scientists create a better model of how dinosaurs evolved into modern birds. The winged dinosaur is still in the process of being dated, and might have lived toward the end of the Jurassic period, which lasted from 208 to 144 million years ago.

The protobird is "very close to the point of divergence" at which a new branch of winged dinosaurs first took flight, said Xu.

The new species, called Anchiornis huxleyi, was discovered in the ashes of volcanoes that were active during the Jurassic and Cretaceous (144 to 65 million years ago) periods in what is now northeastern China.

Anchiornis, which is Greek for "close to bird," measured just 13 inches (34 centimeters) from head to tail and weighed about 4 ounces (110 grams).

The dinosaur's body and forelimbs were covered with feathers, and it "might have had some aerial capability," Xu said.

"Anchiornis is one of the smallest theropod dinosaurs ever uncovered," Xu explained. Theropods were a group of carnivorous dinosaurs that walked on two legs.

Taking Wing

The fossil provides new clues about how feathers, wings, and flight progressively appeared among theropods, along with evidence that certain types of feathered dinosaurs decreased in stature even as their forelimbs became elongated.

The compact structure of Anchiornis "reinforces the deduction that small size evolved early in the history of birds," Xu explained.

"The wrist is a big part of the formation of wings, and pivotal to flight," Xu added. "During flight, steering and flapping greatly depend on the wrist."

Despite this protobird's relatively advanced feathers and wrist, it is unclear if Anchiornis could actually engage in powered flight.

"Behavior and biomechanics are very difficult to determine solely from the fossil record, and perhaps flight is impossible to determine," said Mark Norell, chairman and curator of the division of paleontology at the American Museum of Natural History in New York.

"Feathers have lots of functions, and probably evolved as thermoregulators," said Norell, who closely examined the fossil during a trip to Beijing.

"Dinosaurs might have used feathers for sexual display or to make themselves appear bigger, or as camouflage to avoid predators," he said.

Patterns of spots and bars evident on one species of feathered dinosaur from China might have functioned as a camouflage defense, Norell added.

Prehistoric Paradise

Xu said that the region in northeastern China where most of the world's feathered dinosaurs, including Anchiornis, have been discovered is a virtual paradise for dinosaur hunting.

"This area has three circles of volcanic activity," with eruptions that intermittently covered and preserved entire biospheres starting from the early Jurassic.

"Volcanos periodically killed the animals and plants and preserved them perfectly in volcanic ash," he said.

"Sometimes the volcanic ash even preserves soft tissues, leaving behind an exceptional 3-D fossil."

credited to news.nationalgeographic.com

When Paul C. Sereno went hunting for dinosaur bones in the Sahara, his career took a sharp turn from paleontology to archaeology. The expedition found what has proved to be the largest known graveyard of Stone Age people who lived there when the desert was green.

In its first comprehensive report, published Thursday, the team described finding about 200 graves belonging to two successive populations. Some burials were accompanied by pottery and ivory ornaments. A girl was buried wearing a bracelet carved from a hippo tusk. A man was seated on the carapace of a turtle.

The most poignant scene was the triple burial of a petite woman lying on her side, facing two young children. The slender arms of the children reached out to the woman in an everlasting embrace. Pollen indicated that flowers had decorated the grave.

The sun-baked dunes at the site, known as Gobero, preserve the earliest and largest Stone Age cemetery in the Sahara, Dr. Sereno’s group reported in the online journal PLoS One. The findings, they wrote, open “a new window on the funerary practices, distinctive skeletal anatomy, health and diet of early hunter-fisher-gatherers, who expanded into the Sahara when climatic conditions were favorable.”

The research was also described at a news conference on Thursday in Washington at the National Geographic Society, a supporter of the project.

The initial inhabitants at Gobero, the Kiffian culture, were tall hunters of wild game who also fished with harpoons carved from animal bone. Later, a more lightly built people, the Ténérians, lived there, hunting, fishing and herding cattle.

Other scientists said the discovery appeared to provide spectacular evidence that nothing, not even the arid expanse of the Sahara, was changeless. About 100 million years ago, this land was forested and occupied by dinosaurs and enormous crocodiles. Around 50,000 years ago, people moved in and left stone tools and mounds of shells, fish bones and other refuse. The lakes dried up in the last Ice Age.

Then the rains and lakes of a fecund Sahara returned about 12,000 years ago, and remained, except for one 1,000-year interval, until about 4,500 years ago. Geologists have long known that the region’s basins retained mineral residue of former lakes, and other explorers have found scatterings of human artifacts from that time, as Dr. Sereno did at Gobero in 2000.

“Everywhere you turned, there were bones belonging to animals that don’t live in the desert,” he said. “I realized we were in the green Sahara.”

Human skeletons were eroding from the dunes, including jawbones with nearly full sets of teeth and finger bones of a tiny hand pointing up from the sand.

From an analysis of the skeletons and pottery, scientists identified the two successive cultures that occupied the settlement. The Kiffians, some of whom stood up to six feet tall, both men and women, lived there during the Sahara’s wettest period, between 10,000 and 8,000 years ago. They were primarily hunter-gatherers who speared huge lake perch with harpoons.

Elena A. A. Garcea, an archaeologist at the University of Cassino in Italy, identified ceramics with wavy lines and zigzag patterns as Kiffian, a culture associated with northern Africa. Pots bearing a pointillistic pattern were linked to the Ténérians, a people named for the Ténéré desert, a stretch of the Sahara known to Tuareg nomads as a “desert within a desert.”

Christopher M. Stojanowski, an archaeologist at Arizona State University, said the two cultures were “biologically distinct groups.” The bones and teeth showed that in contrast to the robust Kiffians, the Ténérians were typically short and lean and apparently led less rigorous lives.

The shapes of the Ténérian skulls are puzzling, researchers said, because they resemble those of Mediterranean people, not other nearby groups.

Asked if he had adjusted to the transition from dinosaur paleontology to Stone Age archaeology, Dr. Sereno said, “It’s still weird for me to be digging up my own species.”

credited to nytimes.com

A treasure trove of information about pre-human New Zealand has been found in feces from giant extinct birds, buried beneath the floor of caves and rock shelters for thousands of years.

Former PhD student Jamie Wood, from the University of Otago, discovered more than 1500 coprolites in remote areas across southern New Zealand, primarily from species of the extinct giant moa, which ranged up to 250 kilograms and three metres in height. Some of the feces recovered were up to 15 centimetres in length.

"Surprisingly for such large birds, over half the plants we detected in the feces were under 30 centimetres in height," says Dr Wood. "This suggests that some moa grazed on tiny herbs, in contrast to the current view of them as mainly shrub and tree browsers. We also found many plant species that are currently threatened or rare, suggesting that the extinction of the moa has impacted their ability to reproduce or disperse."

"New Zealand offers a unique chance to reconstruct how a `megafaunal ecosystem' functioned," says Professor Alan Cooper, Director of the Australian Centre for Ancient DNA, which performed the DNA typing.

"You can't do this elsewhere in the world because the giant species became extinct too long ago, so you don't get such a diverse record of species and habitats. Critically, the interactions between animals and plants we see in the poo provides key information about the origins and background to our current environment, and predicting how it will respond to future climate change and extinctions."

"When animals shelter in caves and rock shelters, they leave feces which can survive for thousands of years if dried out," Professor Cooper says. "Given the arid conditions, Australia should probably have similar deposits from the extinct giant marsupials. A key question for us is 'where has all the Australian poo gone?'"

Other University of Adelaide members of the research team include Dr Jeremy Austin, Dr Trevor Worthy and Mr Nicolas Rawlence from the Australian Centre for Ancient DNA, part of the University's newly-established Environment Institute.

The team's findings have recently been published in Quaternary Science Reviews, an international geological research journal.

credited to University of Adelaide (2009, January 13). Giant Bird Feces Record Pre-human New Zealand. ScienceDaily. Retrieved March 17, 2009, from http://www.sciencedaily.com­/releases/2009/01/090112110115.htm

Abundant tiny particles of diamond dust exist in sediments dating to 12,900 years ago at six North American sites, adding strong evidence for Earth's impact with a rare swarm of carbon-and-water-rich comets or carbonaceous chondrites, reports a nine-member scientific team.

Last year a 26-member team from 16 institutions proposed that a cosmic impact event, possibly by multiple airbursts of comets, set off a 1,300-year-long cold spell known as the Younger Dryas, fragmented the prehistoric Clovis culture and led to the extinction of a large range of animals, including mammoths, across North America. The team's paper was published in the Oct. 9, 2007, issue of the Proceedings of the National Academy of Sciences.

Now, reporting in the Jan. 2 issue of the journal Science, a team led by the University of Oregon's Douglas J. Kennett, a member of the original research team, report finding billions of nanometer-sized diamonds concentrated in sediments -- weighing from about 10 to 2,700 parts per billion -- in the six locations during digs funded by the National Science Foundation.

"The nanodiamonds that we found at all six locations exist only in sediments associated with the Younger Dryas Boundary layers, not above it or below it," said Kennett, a UO archaeologist. "These discoveries provide strong evidence for a cosmic impact event at approximately 12,900 years ago that would have had enormous environmental consequences for plants, animals and humans across North America."

The Clovis culture of hunters and gatherers was named after hunting tools referred to as Clovis points, first discovered in a mammoth's skeleton in 1926 near Clovis, N.M. Clovis sites later were identified across the United States, Mexico and Central America. Clovis people possibly entered North America across a land bridge from Siberia. The peak of the Clovis era is generally considered to have run from 13,200 to 12,900 years ago. One of the diamond-rich sediment layers reported sits directly on top of Clovis materials at the Murray Springs site.

The eight co-authors on the Science paper were: Kennett's father, James P. Kennett of the University of California, Santa Barbara; A. West of GeoScience Consulting in Dewey, Ariz.; C. Mercer of the National Institute for Materials Science in Tsukuba, Japan; Que Hee of the University of California, Los Angeles; L. Bement of the Oklahoma Archaeological Survey at the University of Oklahoma; T.E. Bunch and M. Sellers, both of Northern Arizona University; and W.S. Wolbach of DePaul University in Chicago.

credited to sciencedaily.com