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Entries in Arqueologia (5)

Sunday
Mar172013

Hundreds of Dinosaur Egg Fossils Found

Researchers in northeastern Spain say they've uncovered hundreds of dinosaur egg fossils, including four kinds that had never been found before in the region. The eggs likely were left behind bysauropods millions of years ago.

Eggs, eggshell fragments and dozens of clutches were nestled in the stratigraphic layers of the Tremp geological formation at the site of Coll de Nargó in the Spanish province of Lleida, which was a marshy region during the Late Cretaceous Period, the researchers said.

"Eggshells, eggs and nests were found in abundance and they all belong to dinosaurs, sauropods in particular," the study's leader, Albert García Sellés from the Miquel Crusafont Catalan Palaeontology Institute, told Spanish news agency SINC this week.

"Up until now, only one type of dinosaur egg had been documented in the region: Megaloolithus siruguei," Sellés added. His team found evidence of at least four other species: Cairanoolithus roussetensisMegaloolithus aureliensisMegaloolithus siruguei and Megaloolithus baghensis. Megaloolithus eggs are thought to be associated with sauropods, long-necked dinosaurs that were among some of the largest to roam the planet.

The Coll de Nargó area is considered one of the most important dinosaur nesting areas in Europe, the researchers said, adding that their study shows it was used by several dinosaurs from the Late Campanian age (around 71 million years ago) to the Late Maastrichtian age (around 67 million years ago).

"We had never found so many nests in the one area before. In addition, the presence of various oospecies (eggs species) at the same level suggests that different types of dinosaurs shared the same nesting area," Sellés said, adding that the dinosaur eggs could help scientists determine the date of future findings at the site.

"It has come to light that the different types of eggs are located at very specific time intervals," Sellés explained to SINC. "This allows us to create biochronological scales with a precise dating capacity. In short, thanks to the collection of oospecies found in Coll de Nargó we have been able to determine the age of the site at between 71 and 67 million years."

The findings are published in the March issue of the journal Cretaceous Research.

Source:

http://news.yahoo.com/hundreds-dinosaur-egg-fossils-found-121945899.html

Sunday
Mar172013

Dinosaur-Era Climate Change Study Suggests Reasons for Turtle Disappearance

This shows Annie Quinney excavating ancient soils in 70 million-year-old rocks in the Drumheller badlands. (Credit: Credit: Kohei Tanaka, University of Calgary.)

The dry, barren prairie around Alberta's Drumheller area was once a lush and subtropical forest on the shores of a large inland sea, with loads of wetlands inhabited by dinosaurs, turtles, crocodiles and small mammals.

But that changed about 71-million-years ago, according to a new study by researchers Annie Quinney and Darla Zelenitsky in paleontology at the University of Calgary. The researchers' calculations show that drastic climate change occurred during a five-million-year period in Alberta's badlands. At this time, the wetlands dried up and the warm humid climate was interrupted by a sudden cool, drying spell.

The study of ancient climate change is important as it helps researchers understand the impact sudden heating and cooling may have had on plants and animals.

"This was a time of change in Alberta, the wetlands disappeared as the inland sea retreated and the climate cooled," says Quinney, a former master's student in the Department of Geoscience. She led the study recently published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology, which was part of her master's degree in the Department of Geoscience.

Dramatic climate change was previously proposed to be responsible for the disappearance of turtles 71-million-years ago, because they were considered to be "climate-sensitive" animals. Results of this research, however, show that the disappearance of turtles came before the climate cooled and instead closely corresponds to habitat disturbances, which was the disappearance of wetlands.

"The big surprise is that some animals, for example turtles, appeared to be more sensitive to habitat disturbances than to climate changes. Therefore, even if climatic conditions are 'ideal,' turtles may disappear or may not recover unless habitats are just right," says Quinney.

Quinney and supervisors Zelenitsky, assistant professor in the Department of Geoscience, and François Therrien of the Royal Tyrrell Museum in Drumheller studied ancient soils preserved in the rocks in the Red Deer River valley near Drumheller that were deposited 72 to 67 million years ago and record information about the past climate and environments.

Researchers calculated precipitation and temperature levels over a five-million year interval and during that time, temperature and precipitation dropped over a few thousand years, and that cooler interval lasted for 500,000 years.

"By studying the structure and chemistry of ancient soils, we were able to estimate the ancient temperature and rainfall that prevailed when those soils formed millions of years ago," says Quinney, who is now completing a PhD at Monash University in Australia on a full scholarship.

Source:

http://www.sciencedaily.com/releases/2013/03/130314144354.htm

Sunday
Mar172013

100-million-year-old spider attack

The only fossil ever discovered of a spider attack on prey caught in its web – a 100 million-year-old snapshot of an engagement caught in amber.

The extraordinarily rare fossils are in a piece of amber that preserved this event in remarkable detail. This spider happened in the Hukawng Valley of Myanmar in the Early Cretaceous – between 97-110 million years ago – almost certainly with dinosaurs wandering nearby.

George Poinar, Jr., is a professor emeritus of zoology at Oregon State University and world expert on insects trapped in amber. He outlined the findings in a study published in the journal Historical Biology. Poinar said:

This was a male wasp that suddenly found itself trapped in a spider web. This was the wasp’s worst nightmare, and it never ended. The wasp was watching the spider just as it was about to be attacked, when tree resin flowed over and captured both of them.

The tree resin that forms amber is renowned for its ability to flow over insects, small plants and other life forms, preserving them in near perfection before it later turns into a semi-precious stone. It often gives scientists a look into the biology of the distant past. This spider, which may have been waiting patiently for hours to capture some prey, was smothered in resin just a split second before its attack.

Source:

http://earthsky.org/todays-image/100-million-year-old-spider-attack?utm_source=EarthSky+News&utm_campaign=a2fd76dce9-EarthSky_News&utm_medium=email

 

Wednesday
Jan232013

Prehistoric Beaches Hold Key to Understanding Climate Change

As many people in the Northeast continue a long and painful recovery in the wake of Hurricane Sandy, scientists are working hard to determine how high and how fast global sea levels are rising. In order to do this, they are looking not only to the future—in the form of computer-generated forecasts—but also to the past. Due to rising levels of carbon dioxide produced by human emissions of greenhouse gases, the Earth is expected to warm at a faster rate over the coming century, a situation that is roughly comparable to the climate change that happened some 3 million years ago, during the mid-Pliocene Epoch. In an effort to find out how high global sea levels rose during the mid-Pliocene, scientists traveled to South Africa to study beach deposits dating to that time, some of which can now be found more than 100 feet above modern sea level.

As reported in the New York Times this week, a team of scientists headed by Dr. Maureen E. Raymo of Columbia University traveled to the southern and western coasts of South Africa last summer to find prehistoric beaches that could contain invaluable records of past climate change. Through often-risky exploration of various sites, including old quarries and diamond mines, the team managed to find 38 suspected beaches dating to the Pliocene Epoch. The beach deposits ranged from 38 feet to 111 feet above modern sea level, indicating how high seas may have risen during that period in Earth’s history.

Past climate research has shown that when the earth’s temperature rises by only a couple of degrees Fahrenheit, polar ice melting causes the global sea level to rise some 25 to 30 feet. The Earth is expected to warm at a faster rate over the coming century, possibly by as much as four or five degrees. Rising sea levels due to melting polar ice have almost certainly contributed to the coastal flooding caused by Hurricane Sandy and other massive storms. The research group Climate Central estimates that an ocean rise of only five feet—within current scientific estimates for the coming century—will produce storm tides on the scale of Sandy’s about every 15 years in New York City.

Many scientists who study climate history, known as paleoclimatologists, have settled on the mid-Pliocene Epoch (roughly 3 million years ago) as a model for what might happen to global sea levels in the coming century. The mid-Pliocene was the first era in earth’s history where temperatures were consistently warmer than what we see today, and roughly comparable to what scientists expect them to be by the end of the 21st century.

One factor complicating the project is that rising sea levels are not the only cause of the variation in height among the Pleistocene beaches found in South Africa and elsewhere. The land itself has undoubtedly also moved over the last several million years, which likely shifted the height of existing beach deposits. Scientists now know that this movement can happen anywhere in the world, even far from known geologic hotspots with long histories of active volcanism, and must take this movement into account in their interpretation of past sea levels.

In the next several years, Raymo and her team plan to gather measurements from ancient beaches on different continents—including North America—in the hopes of determining the maximum global sea level rise that occurred during the mid-Pliocene. Previous estimates of that number, though not based on solid evidence, have ranged from 15 feet to 130 feet above today’s ocean, with 80 feet as the most commonly cited figure. If their research confirms such a drastic rise, it could suggest that the world’s largest ice sheet, which covers eastern Antarctica, is vulnerable to melting, contradicting computer forecasts predicting its stability even as global temperatures rise.

Source: http://www.history.com/news/prehistoric-beaches-hold-key-to-understanding-climate-change

Tuesday
Oct022012

Prehistoric Writing: Stone Age Jottings

http://infographicboard.com/science-2/prehistoric-writing-stone-age-jottings/