A team of scientists and archaeologists, including UCL's Professor David Wengrow and Dr Alice Stevenson, have been able to set a robust timeline for the first eight dynastic rulers of ancient Egypt.
The study, which is published in the journal Proceedings of the Royal Society A, shows that Egypt formed far more rapidly than was previously thought and also updates the techniques first developed by Flinders Petrie over 100 years ago,.
Having obtained over 100 fresh radiocarbon dates for hair, bone and plant samples excavated at several key sites, the team from UCL and University of Oxford were able to use mathematical modelling to combine the new radiocarbon dates with existing archaeological evidence to establish the chronology of Early Egypt between 4500 and 2800 BC and the likeliest date for each king's accession.
Until now there have been no verifiable chronological records for this period or the process leading up to the formation of the Egyptian state, which occurred several centuries before the first pyramids were built.
Instead scholars relied on archaeological evidence alone, using a method established by Flinders Petrie in which the evolving styles of ceramics excavated at human burial sites are used to piece together the timings of key chronological events in the Predynastic period and the First Dynasty.
Dr Alice Stevenson, co-author of the study and curator of the UCL Petrie Museum, said: "Petrie was the first person to really apply a type of mathematical modelling to archaeology by developed the first example of what we now call 'seriation' in archaeology to create a relative dating – i.e. an ordering of material that is seen to be equivalent to a timescale. It was arguably his greatest achievement and what he is internationally recognised in archaeology for and not just in Egyptology."
The museum also holds Petrie's sequence dating cards - the method by which he put into sequence 900 prehistoric Egyptian graves with their pottery assemblages - providing the first framework for structuring the chronology of the period running up to the emergence of the first kings of Egypt. It is also why the museum has a pottery gallery devoted to showing his chronological sequence of pottery.
Dr Stevenson said: "This project is the first example of the robust use of mathematical modelling with absolute dates – so there's a really nice parallel with Petrie's approach at the end of the 19th century with new approaches at the beginning of the 21st.
"Petrie's typology was both a crucial reference point for the project and something we tested with absolute dates and mathematical modelling. We also used materials in the museum excavated by Petrie's teams – so plant materials, basketry etc. – as the specimens for getting new radiocarbon dates."
Egypt was the world's first territorial state to be brought under one political ruler, and the new dating evidence suggests that this period of unification happened far more quickly than previously thought.
"The period between 4500 BC and 2800 BC witnessed profound changes in social, political and economic conditions that formed the very foundation of the ancient Egyptian state. The results of this project give archaeologists an invaluable framework for not only visualizing this sequence, but more importantly for understanding the pace of these cultural transformations. It will allow us to ask new questions about the development of ancient Egyptian society and permit us to link our chronologies with those from surrounding regions, including Mesopotamia," said Dr Stevenson.
'An absolute chronology for early Egypt using radiocarbon dating and Bayesian statistical modelling' by Michael Dee et al will be published by the journal, Proceedings of the Royal Society A, on 4 September 2013.
martes, 10 de septiembre de 2013
The cranium of the fossil juvenile ape found at a Miocene site in Yunnan Province, China. (Credit: Denise Su/Cleveland Museum of Natural History)
Posted by Vicki Fong-Penn State on September 9, 2013
A 6-million-year-old ape cranium found in China may offer a clearer picture of the end of the Miocene, a time when apes had become extinct in most of Eurasia.
Juvenile crania of apes and hominins are extremely rare in the fossil record, especially those of infants and young juveniles. This cranium is only the second relatively complete cranium of a young juvenile in the entire Miocene—23 million to 5 million years ago—record of fossil apes throughout the Old World, and both were discovered from the late Miocene of Yunnan Province.
Shuitangba, the site from which it was recovered, has also produced remains of the fossil monkey, Mesopithecus, which represents the earliest occurrence of monkeys in East Asia.
"The fossils recovered from Shuitangba constitute one of the most important collections of late Miocene fossils brought to light in recent decades because they represent a snapshot from a critical transitional period in earth history," says Nina Jablonski, a co-author and Distinguished Professor of Anthropology at Penn State University. The paper detailing the discovery is available online in the Chinese Science Bulletin.
"The ape featured in the current paper typifies animals from the lush tropical forests that blanketed much of the world's subtropical and tropical latitudes during the Miocene epoch, while the monkey and some of the smaller mammals exemplify animals from the more seasonal environments of recent times."
Another member of the research team and co-author, Jay Kelley of the Institute of Human Origins at Arizona State University, says the preservation of the new cranium is excellent, with only minimal post-depositional distortion. "This is important because all previously discovered adult crania of the species to which it is assigned, Lufengpithecus lufengensis, were badly crushed and distorted during the fossilization process," Kelley says.
"In living ape species, cranial anatomy in individuals at the same stage of development as the new fossil cranium already show a close resemblance to those of adults. Therefore, the new cranium, despite being from a juvenile, gives researchers the best look at the cranial anatomy of Lufengpithecus lufengensis. Partly because of where and when Lufengpithecus lived, it is considered by most to be in the lineage of the extant orangutan, now confined to Southeast Asia but known from the late Pleistocene of southern China as well."
The researchers noted, however, the cranium shows little resemblance to those of living orangutans, and in particular, shows none of what are considered to be key diagnostic features of orangutan crania. Lufengpithecus therefore appears to represent a late surviving lineage of Eurasian apes, but with no certain affinities yet clear.
The survival of this lineage is not entirely surprising since southern China was less affected by climatic deterioration during the later Miocene that resulted in the extinction of many ape species throughout the rest of Eurasia. The researchers are hopeful that further excavations will produce the remains of adult individuals, which will allow them to better assess the relationships among members of this lineage as well as the relationships of this lineage to other fossil and extant apes.
"In addition to the ape, we have recovered hundreds of specimens of other animals and plants," says study co-author Denise Su, curator of paleobotany and paleoecology at the Cleveland Museum of Natural History.
"We are looking forward to going back to Shuitangba next year to continue fieldwork and, hopefully, find more specimens of not only the ape but other animals and plants that will tell us more about the environment. Given what we have recovered so far, Shuitangba has great potential to help us learn more about the environment in the latest part of the Miocene in southern China and the evolution of the plants and animals found there."
The National Science Foundation, Bryn Mawr College, American Association of Physical Anthropologists, the Yunnan National Science Foundation, the Zhaotong government, National Basic Research Program of China, and the National Natural Science Foundation of China supported this project.
Source: Penn State University
jueves, 29 de agosto de 2013
The last glacial maximum was a time when Earth's far northern and far southern latitudes were largely covered in ice sheets and sea levels were low. Over much of the planet, glaciers were at their greatest extent roughly 20,000 years ago. But according to a study headed by University of Pennsylvania geologist Jane Willenbring, that wasn't true in at least one part of southern Europe. Due to local effects of temperature and precipitation, the local glacial maximum occurred considerably earlier, around 26,000 years ago.
The finding sheds new light on how regional climate has varied over time, providing information that could lead to more-accurate global climate models, which predict what changes Earth will experience in the future.
Willenbring, an assistant professor in Penn's Department of Earth and Environmental Science in the School of Arts and Sciences, teamed with researchers from Spain, the United Kingdom, China and the United States to pursue this study of the ancient glaciers of southern Europe.
"We wanted to unravel why and when glaciers grow and shrink," Willenbring said.
In the study site in central Spain, it is relatively straightforward to discern the size of ancient glaciers, because the ice carried and dropped boulders at the margin. Thus a ring of boulders marks the edge of the old glacier.
It is not as easy to determine what caused the glacier to grow, however. Glaciers need both moisture and cold temperatures to expand. Studying the boulders that rim the ancient glaciers alone cannot distinguish these contributions. Caves, however, provide a way to differentiate the two factors. Stalagmites and stalactites — the stony projections that grow from the cave floor and ceiling, respectively — carry a record of precipitation because they grow as a result of dripping water.
"If you add the cave data to the data from the glaciers, it gives you a neat way of figuring out whether it was cold temperatures or higher precipitation that drove the glacier growth at the time," Willenbring said.
The researchers conducted the study in three of Spain's mountain ranges: the Bejár, Gredos and Guadarrama. The nearby Eagle Cave allowed them to obtain indirect precipitation data.
To ascertain the age of the boulders strewn by the glaciers and thus come up with a date when glaciers were at their greatest extent, Willenbring and colleagues used a technique known as cosmogenic nuclide exposure dating, which measures the chemical residue of supernova explosions. They also used standard radiometric techniques to date stalagmites from Eagle Cave, which gave them information about fluxes in precipitation during the time the glaciers covered the land.
"Previously, people believe the last glacial maximum was somewhere in the range of 19-23,000 years ago," Willenbring said. "Our chronology indicates that's more in the range of 25-29,000 years ago in Spain."
The geologists found that, although temperatures were cool in the range of 19,000-23,000 years ago, conditions were also relatively dry, so the glaciers did not regain the size they had obtained several thousand years earlier, when rain and snowfall totals were higher. They reported their findings in the journal Scientific Reports.
Given the revised timeline in this region, Willenbring and colleagues determined that the increased precipitation resulted from changes in the intensity of the sun's radiation on the Earth, which is based on the planet's tilt in orbit. Such changes can impact patterns of wind, temperature and storms.
"That probably means there was a southward shift of the North Atlantic Polar Front, which caused storm tracks to move south, too," Willenbring said. "Also, at this time there was a nice warm source of precipitation, unlike before and after when the ocean was colder."
Willenbring noted that the new date for the glacier maximum in the Mediterranean region, which is several thousands of years earlier than the date the maximum was reached in central Europe, will help provide more context for creating accurate global climate models.
"It's important for global climate models to be able to test under what conditions precipitation changes and when sources for that precipitation change," she said. "That's particularly true in some of these arid regions, like the American Southwest and the Mediterranean."
When glaciers were peaking in the Mediterranean around 26,000 years ago, the American Southwest was experiencing similar conditions. Areas that are now desert were moist. Large lakes abounded, including Lake Bonneville, which covered much of modern-day Utah. The state's Great Salt Lake is what remains.
"Lakes in this area were really high for 5,000-10,000 years, and the cause for that has always been a mystery," Willenbring said. "By looking at what was happening in the Mediterranean, we might eventually be able to say something about the conditions that led to these lakes in the Southwest, too."
This research was supported by the Ministerio de Ciencia e Innovación and the Junta de Comunidades de Castilla-La Mancha.
sábado, 20 de julio de 2013
Researchers at the University of Warwick have recovered tuberculosis (TB) genomes from the lung tissue of a 215-year old mummy using a technique known as metagenomics.
The team, led by Professor Mark Pallen, Professor of Microbial Genomics at Warwick Medical School, working with Helen Donoghue at University College London and collaborators in Birmingham and Budapest, sought to use the technique to identify TB DNA in a historical specimen.
The term 'metagenomics' is used to describe the open-ended sequencing of DNA from samples without the need for culture or target-specific amplification or enrichment. This approach avoids the complex and unreliable workflows associated with culture of bacteria or amplification of DNA and draws on the remarkable throughput and ease of use of modern sequencing approaches.
The sample came from a Hungarian woman, Terézia Hausmann, who died aged 28 on 25 December 1797. Her mummified remains were recovered from a crypt in the town of Vác, Hungary. When the crypt was opened in 1994, it was found to contain the naturally mummified bodies of 242 people. Molecular analyses of the chest sample in a previous study confirmed the diagnosis of tuberculosis and hinted that TB DNA was extremely well preserved in her body.
Professor Pallen explained the importance of the breakthrough, "Most other attempts to recover DNA sequences from historical or ancient samples have suffered from the risk of contamination, because they rely on amplification of DNA in the laboratory, plus they have required onerous optimisation of target-specific assays. The beauty of metagenomics is that it provides a simple but highly informative, assumption-free, one-size-fits-all approach that works in a wide variety of contexts. A few months ago we showed that metagenomics allowed us to identify an E. coli outbreak strains from faecal samples and a few weeks ago a similar approach was shown by another group to deliver a leprosy genome from historical material".
The research, published this week in the New England Journal of Medicine, showed that Terézia Hausmann suffered from a mixed infection with two different strains of the TB bacterium. This information, combined with work on contemporary tuberculosis, highlights the significance of mixed-strain infections, particularly when tuberculosis is highly prevalent.
Professor Pallen added, "It was fascinating to see the similarities between the TB genome sequences we recovered and the genome of a recent outbreak strain in Germany. It shows once more that using metagenomics can be remarkably effective in tracking the evolution and spread of microbes without the need for culture—in this case, metagenomes revealed that some strain lineages have been circulating in Europe for more than two centuries."
To arrange interviews with author Mark J. Pallen, M.A., M.D., Ph.D., email firstname.lastname@example.org.
Alternatively, contact Warwick Medical School Press Officer Luke Harrison on +44 (0) 2476 574255/150483 or +44 (0) 7920531221 email@example.com
viernes, 19 de julio de 2013
July 17, 2013, Salt Lake City, UT – A remarkable new species of horned dinosaur has been unearthed in Grand Staircase-Escalante National Monument, southern Utah. The huge plant-eater inhabited Laramidia, a landmass formed when a shallow sea flooded the central region of North America, isolating western and eastern portions for millions of years during the Late Cretaceous Period. The newly discovered dinosaur, belonging to the same family as the famous Triceratops, was announced today in the British scientific journal, Proceedings of the Royal Society B.
The study, funded in large part by the Bureau of Land Management and the National Science Foundation, was led by Scott Sampson, when he was the Chief Curator at the Natural History Museum of Utah at the University of Utah. Sampson is now the Vice President of Research and Collections at the Denver Museum of Nature & Science. Additional authors include Eric Lund (Ohio University; previously a University of Utah graduate student), Mark Loewen (Natural History Museum of Utah and Dept. of Geology and Geophysics, University of Utah), Andrew Farke (Raymond Alf Museum), and Katherine Clayton (Natural History Museum of Utah).
Horned dinosaurs, or "ceratopsids," were a group of big-bodied, four-footed herbivores that lived during the Late Cretaceous Period. As epitomized by Triceratops, most members of this group have huge skulls bearing a single horn over the nose, one horn over each eye, and an elongate, bony frill at the rear. The newly discovered species, Nasutoceratops titusi, possesses several unique features, including an oversized nose relative to other members of the family, and exceptionally long, curving, forward-oriented horns over the eyes. The bony frill, rather than possessing elaborate ornamentations such as hooks or spikes, is relatively unadorned, with a simple, scalloped margin. Nasutoceratops translates as "big-nose horned face," and the second part of the name honors Alan Titus, Monument Paleontologist at Grand Staircase-Escalante National Monument, for his years of research collaboration.
For reasons that have remained obscure, all ceratopsids have greatly enlarged nose regions at the front of the face. Nasutoceratops stands out from its relatives, however, in taking this nose expansion to an even greater extreme. Scott Sampson, the study's lead author, stated, "The jumbo-sized schnoz of Nasutoceratops likely had nothing to do with a heightened sense of smell—since olfactory receptors occur further back in the head, adjacent to the brain—and the function of this bizarre feature remains uncertain."
Paleontologists have long speculated about the function of horns and frills on horned dinosaurs. Ideas have ranged from predator defense and controlling body temperature to recognizing members of the same species. Yet the dominant hypothesis today focuses on competing for mates—that is, intimidating members of the same sex and attracting members of the opposite sex. Peacock tails and deer antlers are modern examples. In keeping with this view, Mark Loewen, a co-author of the study claimed that, "The amazing horns of Nasutoceratops were most likely used as visual signals of dominance and, when that wasn't enough, as weapons for combatting rivals."
A Treasure Trove of Dinosaurs on the Lost Continent of Laramidia
Nasutoceratops was discovered in Grand Staircase-Escalante National Monument (GSENM), which encompasses 1.9 million acres of high desert terrain in south-central Utah. This vast and rugged region, part of the National Landscape Conservation System administered by the Bureau of Land Management, was the last major area in the lower 48 states to be formally mapped by cartographers. Today GSENM is the largest national monument in the United States. Sampson proclaimed that, "Grand Staircase-Escalante National Monument is the last great, largely unexplored dinosaur boneyard in the lower 48 states."
For most of the Late Cretaceous, exceptionally high sea levels flooded the low-lying portions of several continents around the world. In North America, a warm, shallow sea called the Western Interior Seaway extended from the Arctic Ocean to the Gulf of Mexico, subdividing the continent into eastern and western landmasses, known as Appalachia and Laramidia, respectively. Whereas little is known of the plants and animals that lived on Appalachia, the rocks of Laramidia exposed in the Western Interior of North America have generated a plethora of dinosaur remains. Laramidia was less than one-third the size of present day North America, approximating the area of Australia.
Most known Laramidian dinosaurs were concentrated in a narrow belt of plains sandwiched between the seaway to the east and mountains to the west. Today, thanks to an abundant fossil record and more than a century of collecting by paleontologists, Laramidia is the best known major landmass for the entire Age of Dinosaurs, with dig sites spanning from Alaska to Mexico. Utah was located in the southern part of Laramidia, which has yielded far fewer dinosaur remains than the fossil-rich north. The world of dinosaurs was much warmer than the present day; Nasutoceratops lived in a subtropical swampy environment about 100 km from the seaway.
Beginning in the 1960's, paleontologists began to notice that the same major groups of dinosaurs seemed to be present all over this Late Cretaceous landmass, but different species of these groups occurred in the north (for example, Alberta and Montana) than in the south (New Mexico and Texas). This finding of "dinosaur provincialism" was very puzzling, given the giant body sizes of many of the dinosaurs together with the diminutive dimensions of Laramidia. Currently, there are five giant (rhino-to-elephant-sized) mammals on the entire continent of Africa. Seventy-six million years ago, there may have been more than two dozen giant dinosaurs living on a landmass about one-quarter that size. Co-author Mark Loewen noted that, "We're still working to figure out how so many different kinds of giant animals managed to co-exist on such a small landmass?" The new fossils from GSENM are helping us explore the range of possible answers, and even rule out some alternatives.
During the past dozen years, crews from the Natural History Museum of Utah, the Denver Museum of Nature & Science and several other partner institutions (e.g., the Utah Geologic Survey, the Raymond Alf Museum of Paleontology, and the Bureau of Land Management) have unearthed a new assemblage of more than a dozen dinosaurs in GSENM. In addition to Nasutoceratops, the collection includes a variety of other plant-eating dinosaurs—among them duck-billed hadrosaurs, armored ankylosaurs, dome-headed pachycephalosaurs, and two other horned dinosaurs, Utahceratops and Kosmoceratops—together with carnivorous dinosaurs great and small, from "raptor-like" predators to a mega-sized tyrannosaur named Teratophoneus. Amongst the other fossil discoveries are fossil plants, insect traces, clams, fishes, amphibians, lizards, turtles, crocodiles, and mammals. Together, this diverse bounty of fossils is offering one of the most comprehensive glimpses into a Mesozoic ecosystem. Remarkably, virtually all of the identifiable dinosaur remains found in GSENM belong to new species, providing strong support for the dinosaur provincialism hypothesis.
Andrew Farke, a study co-author, noted that, "Nasutoceratops is one of a recent landslide of ceratopsid discoveries, which together have established these giant plant-eaters as the most diverse dinosaur group on Laramidia."
Eric Lund, another co-author as well as the discoverer of the new species, stated that, "Nasutoceratops is a wondrous example of just how much more we have to learn about with world of dinosaurs. Many more exciting fossils await discovery in Grand Staircase-Escalante National Monument."
Fact Sheet: Major Points of the Paper
(1) A remarkable new horned dinosaurs Nasutoceratops titusi, has been unearthed in Grand Staircase-Escalante National Monument, southern Utah.
(2) Nasutoceratops is distinguished by a number of unique features, including an oversized nose and elongate, forward-curving horns over the eyes.
(3) This animal lived in a swampy, subtropical setting on the "island continent" of western North America, also known as "Laramidia."
(4) Nasutoceratops appears to belong to a previously unrecognized group of horned dinosaurs that lived on Laramidia, and provides strong evidence supporting the idea that distinct northern and southern dinosaur communities lived on this landmass for over a million years during the Late Cretaceous.
New Dinosaur Name: Nasutoceratops titusi.
Age and Geography