When age matters: precise dating of ancient charcoal found near skull is helping reveal unique period in prehistory

A partial human skull unearthed in 2008 in northern Israel may hold some clues as to when and where humans and Neanderthals might have interbred. The key to addressing this, as well as other important issues, is precisely determining the age of the skull. A combination of dating methods, one of them performed by Dr. Elisabetta Boaretto, head of the Weizmann Institute’s D-REAMS (DANGOOR Research Accelerator Mass Spectrometry) laboratory, has made it possible to define the period of time that the cave was occupied and thus the skull’s age. The combined dating provides evidence that Homo sapiens and Homo neanderthalensis could have lived side by side in the area.

The Manot Cave, a natural limestone formation, had been sealed for some 15,000 years. It was discovered by a bulldozer clearing the land for development, and the first to find the partial skull, which was sitting on a ledge, were spelunkers exploring the newly-opened cave. Five excavation seasons uncovered a rich deposit, with stone tools and stratified occupation levels covering a period of time from at least 55,000 to 27,000 years ago.
Dating the skull presented a number of difficulties. “Because it was already removed from the layer where it was presumably deposited,” says Dr. Elisabetta Boaretto, “we had to look for clues to tell us where and when it belonged in the setting of the archaeological record in the cave.”
The age of the skull was first determined to be 54.7 thousand years old by a technique known as the uranium-thorium method, which was applied to the thin mineral deposit on the skull. But the estimated possible error in that type of method is plus or minus 5.5 thousand years. To obtain independent confirmation of the date, a different type of dating was required, e.g., radiocarbon dating.
To narrow down the possible range of the skull’s age and determine when the skull’s owner had lived in the cave, the archaeological team led by Prof. Israel Hershkovitz of Tel Aviv University, Dr. Ofer Marder of Ben Gurion University and Dr. Omry Barzilai of the Israel Antiquities Authority turned to Dr. Boaretto. She and her team participated in the excavation of the cave and applied radiocarbon dating to carefully selected charcoal remains, so that the whole cave, and thus the timing of human occupation, was mapped. The agreement between the two methods — carbon and uranium-thorium — provided the necessary support for the “correction” in the original uranium-thorium dating of the skull, which then helped fix the true age of the skull at around 55,000 years.
The date and shape of the Manot Cave skull provides some intriguing evidence that humans and Neanderthals might have interbred sometime during the human trek out of Africa, most likely as the former passed through the Middle East before spreading out north and east. The 55,000-year-old partial skull is the first evidence of a human residing in the region at the same time as Neanderthals, whose remains have been found at several nearby sites. Archaeologists are now searching for more evidence of ancient human habitation in the cave. If, indeed, the mixing between humans and Neanderthals took place in this area, it would suggest that the owner of the skull and his kin may have been the ancestors of all modern non-Africans.

International team of scientists launches fossil database

Have you ever wondered exactly when a certain group of plants or animals first evolved? This week a groundbreaking new resource for scientists will go live, and it is designed to help answer just those kinds of questions. The Fossil Calibration Database, a free, open-access resource that stores carefully vetted fossil data, is the result of years of work from a worldwide team led by Dr. Daniel Ksepka, Curator of Science at the Bruce Museum in Greenwich, and Dr. James Parham, Curator at the John D. Cooper Archaeological and Paleontological Center in Orange County, California, funded through the National Evolutionary Synthesis Center (NESCent).
“Fossils provide the critical age data we need to unlock the timing of major evolutionary events,” says Dr. Ksepka. “This new resource will provide the crucial fossil data needed to calibrate ‘molecular clocks’ which can reveal the ages of plant and animal groups that lack good fossil records. When did groups like songbirds, flowering plants, or sea turtles evolve? What natural events were occurring that may have had an impact? Precisely tuning the molecular clock with fossils is the best way we have to tell evolutionary time.”
More than twenty paleontologists, molecular biologists, and computer programmers from five different countries contributed to the design and implementation of this new database. The Fossil Calibrations Database webpage launches on Tuesday February 24th, and a series of five peer-reviewed papers and an editorial on the topic will appear in the scientific journal Palaeontologia Electronica, describing the endeavor. Dr. Ksepka is the author of one of the papers and co-author of the editorial.
“This exciting field of study, known as ‘divergence dating,’ is important for understanding the origin and evolution of biodiversity, but has been hindered by the improper use of data from the fossil record,” says Dr. Parham. “The Fossil Calibration Database addresses this issue by providing molecular biologists with paleontologist-approved data for organisms across the Tree of Life.”
The Tree of Life? “Think of it as a family tree of all species,” explains Dr. Ksepka.
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The above story is based on materials provided by Bruce Museum. Note: Materials may be edited for content and length.

Ancient rocks show life could have flourished on Earth 3.2 billion years ago

A spark from a lightning bolt, interstellar dust, or a subsea volcano could have triggered the very first life on Earth. But what happened next? Life can exist without oxygen, but without plentiful nitrogen to build genes — essential to viruses, bacteria and all other organisms — life on the early Earth would have been scarce.
The ability to use atmospheric nitrogen to support more widespread life was thought to have appeared roughly 2 billion years ago. Now research from the University of Washington looking at some of the planet’s oldest rocks finds evidence that 3.2 billion years ago, life was already pulling nitrogen out of the air and converting it into a form that could support larger communities.
“People always had the idea that the really ancient biosphere was just tenuously clinging on to this inhospitable planet, and it wasn’t until the emergence of nitrogen fixation that suddenly the biosphere become large and robust and diverse,” said co-author Roger Buick, a UW professor of Earth and space sciences. “Our work shows that there was no nitrogen crisis on the early Earth, and therefore it could have supported a fairly large and diverse biosphere.”
The results were published Feb. 16 in Nature.
The authors analyzed 52 samples ranging in age from 2.75 to 3.2 billion years old, collected in South Africa and northwestern Australia. These are some of the oldest and best-preserved rocks on the planet. The rocks were formed from sediment deposited on continental margins, so are free of chemical irregularities that would occur near a subsea volcano. They also formed before the atmosphere gained oxygen, roughly 2.3 to 2.4 billion years ago, and so preserve chemical clues that have disappeared in modern rocks.
Even the oldest samples, 3.2 billion years old — three-quarters of the way back to the birth of the planet — showed chemical evidence that life was pulling nitrogen out of the air. The ratio of heavier to lighter nitrogen atoms fits the pattern of nitrogen-fixing enzymes contained in single-celled organisms, and does not match any chemical reactions that occur in the absence of life.
“Imagining that this really complicated process is so old, and has operated in the same way for 3.2 billion years, I think is fascinating,” said lead author Eva Stüeken, who did the work as part of her UW doctoral research. “It suggests that these really complicated enzymes apparently formed really early, so maybe it’s not so difficult for these enzymes to evolve.”
Genetic analysis of nitrogen-fixing enzymes have placed their origin at between 1.5 and 2.2 billion years ago.
“This is hard evidence that pushes it back a further billion years,” Buick said. Fixing nitrogen means breaking a tenacious triple bond that holds nitrogen atoms in pairs in the atmosphere and joining a single nitrogen to a molecule that is easier for living things to use. The chemical signature of the rocks suggests that nitrogen was being broken by an enzyme based on molybdenum, the most common of the three types of nitrogen-fixing enzymes that exist now. Molybdenum is now abundant because oxygen reacts with rocks to wash it into the ocean, but its source on the ancient Earth — before the atmosphere contained oxygen to weather rocks — is more mysterious.
The authors hypothesize that this may be further evidence that some early life may have existed in single-celled layers on land, exhaling small amounts of oxygen that reacted with the rock to release molybdenum to the water.
“We’ll never find any direct evidence of land scum one cell thick, but this might be giving us indirect evidence that the land was inhabited,” Buick said. “Microbes could have crawled out of the ocean and lived in a slime layer on the rocks on land, even before 3.2 billion years ago.”
Future work will look at what else could have limited the growth of life on the early Earth. Stüeken has begun a UW postdoctoral position funded by NASA to look at trace metals such as zinc, copper and cobalt to see if one of them controlled the growth of ancient life.

Amber fossil links earliest grasses, dinosaurs and fungus used to produce LSD

A perfectly preserved amber fossil from Myanmar has been found that provides evidence of the earliest grass specimen ever discovered — about 100 million years old — and even then it was topped by a fungus similar to ergot, which for eons has been intertwined with animals and humans.
Ergot has played roles as a medicine, a toxin, and a hallucinogen; been implicated in everything from disease epidemics to the Salem witch trials; and more recently provided the hallucinogenic drug LSD.
Apparently both ergot and the grasses that now form most of the diet for the human race evolved together.
And if they already seemed a little scary, imagine a huge sauropod dinosaur that just ate a large portion of this psychotropic fungus, which in other animal species can cause anything from hallucinations to delirium, gangrene, convulsions or the staggers. The fungus, the grasses it lived on and dinosaurs that ate grass co-existed for millions of years.
The findings and analysis of this remarkable fossil were just published online in the journal Palaeodiversity, by researchers from Oregon State University, the USDA Agricultural Research Service and Germany.
“It seems like ergot has been involved with animals and humans almost forever, and now we know that this fungus literally dates back to the earliest evolution of grasses,” said George Poinar, Jr., an internationally recognized expert on the life forms found in amber and a faculty member in the OSU College of Science.
“This is an important discovery that helps us understand the timeline of grass development, which now forms the basis of the human food supply in such crops as corn, rice or wheat,” Poinar said. “But it also shows that this parasitic fungus may have been around almost as long as the grasses themselves, as both a toxin and natural hallucinogen.
“There’s no doubt in my mind that it would have been eaten by sauropod dinosaurs, although we can’t know what exact effect it had on them.”
Amber begins as a tree sap that can flow around small plant and animal forms and permanently preserve them, as it fossilizes into a semi-precious stone. Poinar is a world leader in examining such specimens and using them to learn more about prehistoric ecosystems.
The fungus in this grass specimen, which is now extinct, was named Palaeoclaviceps parasiticus. It’s very similar to the fungus Claviceps, commonly known as ergot. The fossil, taken from amber mines in Myanmar, dates 97-110 million years ago to the early-to-mid Cretaceous, when the land was still dominated by dinosaurs and conifers, but the earliest flowering plants, grasses and small mammals were beginning to evolve. The fossil shows a grass floret tipped by the dark fungus.
Much later in evolution, grasses would become a powerful life form on Earth, creating vast prairies, nourishing herds of animals, and eventually providing for the domestication of range animals and the cultivation of many food crops. The rise of crop agriculture changed the entire development of the human race, and it’s now estimated that grasses compose about 20 percent of global vegetation.
Researchers also noted in their report that “few fungi have had a greater historical impact on society than ergot.”
Some grasses have natural defense mechanisms, and ergot may be one of them, helping to repel herbivores. It’s bitter and not a preferred food to livestock, and it’s still a problem in cereal and grass seed production, as well as pastures and grazing land.
In animal and human history, the fungus has been known to cause delirium, irrational behavior, convulsions, severe pain, gangrenous limbs and death. In cattle it causes a disease called the “Paspalum staggers.” In the Middle Ages it sometimes killed thousands of people during epidemics when ergot-infected rye bread was more common. It’s been used as a medicine to induce abortion or speed labor in pregnant women, and one researcher — whose findings have been disputed — suggested it may have played a role in the Salem witch trials.
More than 1,000 compounds have been extracted or derived from it, some of them valuable drugs. They also included, in the mid-1900s, the powerful psychedelic compound lysergic acid diethylamide, or LSD, that is still being studied and has been widely used as an illegal recreational drug.
Ergot is strange. And a very, very old fossil now makes clear that it’s been around about as long as grass itself.

Paleontologist names a carnivorous reptile that preceded dinosaurs

Finding a new species of dinosaur is pretty rare. Getting a hand in the discovery and naming of one — that’s rarer still.

Or it would be for anyone other than 32-year-old Sterling Nesbitt, an assistant professor of geological sciences in the College of Science and the newest addition to Virginia Tech’s paleontology team.
Nesbitt has been responsible for naming more than half a dozen reptiles (including dinosaurs) in his young career.
His latest addition to the paleontological vernacular is Nundasuchus, (noon-dah-suh-kis) a 9-foot-long carnivorous reptile with steak knifelike teeth, bony plates on the back, and legs that lie under the body.
Nundasuchus is not a dinosaur, but one of the large reptiles that lived before dinosaurs took over the world.
“The full name is actually Nundasuchus songeaensis,” Nesbitt explained. “It’s Swahili mixed with Greek.”
The basic meaning of Nundasuchus, is “predator crocodile,” “Nunda” meaning predator in Swahili, and “suchus” a reference to a crocodile in Greek.
“The ‘songeaensis’ comes from the town, Songea, near where we found the bones,” Nesbitt said. “The reptile itself was heavy-bodied with limbs under its body like a dinosaur, or bird, but with bony plates on its back like a crocodilian.”
The new, albeit ancient, reptile, is featured online in the Journal of Vertebrate Paleontology.
“We discovered the partial skeleton in 2007 when I was a graduate student, but it took some years to piece the bones together as they were in thousands of pieces,” Nesbitt said.
Although a large number of skeleton bones were found, most of the skull was not recovered despite three trips to the site and more than 1,000 hours spent painstakingly piecing the bones back together and cleaning them.
Nundasuchus was found in southwestern Tanzania, while Nesbitt and a team of researchers were looking for prehistoric relatives of birds and crocodiles, but not really expecting to find something entirely new.
“There’s such a huge gap in our understanding around the time when the the common ancestor of birds and crocodilians was alive — there isn’t a lot out there in the fossil record from that part of the reptile family tree,” Nesbitt said. “This helps us fill in some gaps in reptile family tree, but we’re still studying it and figuring out the implications.”
The find itself was a bit of a “eureka moment” for the team. Nesbitt said he realized very quickly what he had found.
“Sometimes you know instantly if it’s new and within about 30 seconds of picking up this bone I knew it was a new species,” he said. “I had hoped to find a leg bone to identify it, and I thought, This is exactly why we’re here’ and I looked down and there were bones everywhere. It turns out I was standing on bones that had been weathering out of the rock for hundreds of years — and it was all one individual of a new species.”
Nesbitt says he has been very lucky to put himself in the right position for finding bones, but it also takes a lot of work doing research on what has been found in various locations through previous research; what type of animals were known to inhabit certain areas; and research into the geological maps of areas to determine the most likely places to find fossils.
Nesbitt has been involved in naming 17 different reptiles, dinosaurs, and dinosaur relatives in the last 10 years, including seven of which he discovered.

Preserved fossil represents oldest record of parental care in group of prehistoric reptiles

New research details how a preserved fossil found in China could be the oldest record of post-natal parental care from the Middle Jurassic.

The specimen, found by a farmer in China, is of an apparent family group with an adult, surrounded by six juveniles of the same species. Given that the smaller individuals are of similar sizes, the group interpreted this as indicating an adult with its offspring, apparently from the same clutch.
A fossil specimen discovered by a farmer in China represents the oldest record of post-natal parental care, dating back to the Middle Jurassic.
The tendency for adults to care for their offspring beyond birth is a key feature of the reproductive biology of living archosaurs — birds and crocodilians — with the latter protecting their young from potential predators and birds, not only providing protection but also provision of food.
This behaviour seems to have evolved numerous times in vertebrates, with evidence of a long evolutionary history in diapsids — a group of amniotes which developed holes in each side of the skull about 300 million years ago and from which all existing lizards, snakes and birds are descended
However, unequivocal evidence of post-natal parental care is extremely rare in the fossil record and is only reported for two types of dinosaurs and varanopid ‘pelycosaurs’ — a reptile which resembled a monitor lizard.
A new study by the Institute of Geology, Chinese Academy of Geological Sciences, Beijing; the University of Lincoln, UK; and Hokkaido University, Japan, presents new evidence of post-natal parental care in Philydrosauras, a choristodere from the Yixian Formation of western Liaoning Province, China. Choristoderes are a group of relatively small aquatic and semi-aquatic diapsid reptiles which emerged in the Middle Jurassic Period more than 160 million years ago.
The team reviewed the fossil record of reproduction in this group using exceptionally preserved skeletons of the aquatic choristoderan Philydrosauras. The specimen was donated to the Jinzhou Paleontological Museum in Jinzhou City four years ago by a local farmer who discovered the skeleton.
The skeletons are of an apparent family group with an adult, surrounded by six juveniles of the same species. Given that the smaller individuals are of similar sizes, the group interpreted this as indicating an adult with its offspring, apparently from the same clutch.
Dr Charles Deeming, from the School of Life Sciences, University of Lincoln, UK, said: “That Philydrosauras shows parental care of the young after hatching suggests protection by the adult, presumably against predators. Their relatively small size would have meant that choristoderes were probably exposed to high predation pressure and strategies, such as live birth, and post-natal parental care may have improved survival of the offspring. This specimen represents the oldest record of post-natal parental care in diapsids to our knowledge and is the latest in an increasingly detailed collection of choristoderes exhibiting different levels of reproduction and parental care.”
A test of whether post-natal parental care is an ancestral behaviour that has persisted in the evolutionary development of amniotes will depend on future fossil discoveries.
The study is published in Geosciences Journal.

Did the Anthropocene begin with the nuclear age?

Scientists identify July 16 1945 as key time boundary in Earth history.
An international group of scientists has proposed a start date for the dawn of the Anthropocene — a new chapter in the Earth’s geological history.
Humans are having such a marked impact on the Earth that they are changing its geology, creating new and distinctive strata that will persist far into the future. This is the idea behind the Anthropocene, a new epoch in Earth history proposed by the Nobel Prize-winning atmospheric chemist Paul Crutzen just 15 years ago. Since then the idea has spread widely through both the sciences and humanities.
But if the Anthropocene is to be a geological epoch — when should it begin? Humans have long affected the environment, and ideas as to when the Anthropocene might start range from the thousands of years ago with the dawn of agriculture, to the Industrial Revolution — and even to the future (for the greatest human-made changes could still be to come).
Now, members of the international working group formally analysing the Anthropocene suggest that the key turning point happened in the mid-twentieth century. This was when humans did not just leave traces of their actions, but began to alter the whole Earth system. There was a ‘Great Acceleration’ of population, of carbon emissions, of species invasions and extinctions, of earth moving, of the production of concrete, plastics and metals.
It included the start, too, of the nuclear age, when artificial radionuclides were scattered across the Earth, from the poles to the Equator, to be leave a detectable signal in modern strata virtually everywhere.
The proposal, signed up to by 26 members of the working group, including lead author Dr Jan Zalasiewicz, who also chairs the working group, and Professor Mark Williams, both of the University of Leicester’s Department of Geology, is that the beginning of the Anthropocene could be considered to be drawn at the moment of detonation of the world’s first nuclear test: on July 16th 1945. The beginning of the nuclear age, it marks the historic turning point when humans first accessed an enormous new energy source — and is also a time level that can be effectively tracked within geological strata, using a variety of geological clues.
Dr Zalasiewicz said: “Like any geological boundary, it is not a perfect marker — levels of global radiation really rose in the early 1950s, as salvoes of bomb tests took place. But it may be the optimal way to resolve the multiple lines of evidence on human-driven planetary change. Time — and much more discussion — will tell.”
This year, the Anthropocene Working Group will put together more evidence on the Anthropocene, including discussion of possible alternative time boundaries. In 2016, the group aims to make recommendations on whether this new time unit should be formalized and, if so, how it might be defined and characterised.

Study casts doubt on mammoth-killing cosmic impact

Rock soil droplets formed by heating most likely came from Stone Age house fires and not from a disastrous cosmic impact 12,900 years ago, according to new research from the University of California, Davis. The study, of soil from Syria, is the latest to discredit the controversial theory that a cosmic impact triggered the Younger Dryas cold period.

The Younger Dryas lasted a thousand years and coincided with the extinction of mammoths and other great beasts and the disappearance of the Paleo-Indian Clovis people. In the 1980s, some researchers put forward the idea that the cool period, which fell between two major glaciations, began when a comet or meteorite struck North America.
In the new study, published online in the Journal of Archaeological Science, scientists analyzed siliceous scoria droplets — porous granules associated with melting — from four sites in northern Syria dating back 10,000 to 13,000 years ago. They compared them to similar scoria droplets previously suggested to be the result of a cosmic impact at the onset of the Younger Dryas.
“For the Syria side, the impact theory is out,” said lead author Peter Thy, a project scientist in the UC Davis Department of Earth and Planetary Sciences. “There’s no way that can be done.”
The findings supporting that conclusion include:
The composition of the scoria droplets was related to the local soil, not to soil from other continents, as one would expect from an intercontinental impact.
The texture of the droplets, thermodynamic modeling and other analyses showed the droplets were formed by short-lived heating events of modest temperatures, and not by the intense, high temperatures expected from a large impact event.
And in a key finding, the samples collected from archaeological sites spanned 3,000 years. “If there was one cosmic impact,” Thy said, “they should be connected by one date and not a period of 3,000 years.”
So if not resulting from a cosmic impact, where did the scoria droplets come from? House fires. The study area of Syria was associated with early agricultural settlements along the Euphrates River. Most of the locations include mud-brick structures, some of which show signs of intense fire and melting. The study concludes that the scoria formed when fires ripped through buildings made of a mix of local soil and straw

Oldest stone tool ever found in Turkey discovered

Scientists have discovered the oldest recorded stone tool ever to be found in Turkey, revealing that humans passed through the gateway from Asia to Europe much earlier than previously thought, approximately 1.2 million years ago.

According to research published in the journal Quaternary Science Reviews, the chance find of a humanly-worked quartzite flake, in ancient deposits of the river Gediz, in western Turkey, provides a major new insight into when and how early humans dispersed out of Africa and Asia.
Researchers from Royal Holloway, University of London, together with an international team from the UK, Turkey and the Netherlands, used high-precision equipment to date the deposits of the ancient river meander, giving the first accurate timeframe for when humans occupied the area.
Professor Danielle Schreve, from the Department of Geography at Royal Holloway, said: “This discovery is critical for establishing the timing and route of early human dispersal into Europe. Our research suggests that the flake is the earliest securely-dated artefact from Turkey ever recorded and was dropped on the floodplain by an early hominin well over a million years ago.”
The researchers used high-precision radioisotopic dating and palaeomagnetic measurements from lava flows, which both pre-date and post-date the meander, to establish that early humans were present in the area between approximately 1.24 million and 1.17 million years ago. Previously, the oldest hominin fossils in western Turkey were recovered in 2007 at Koçabas, but the dating of these and other stone tool finds were uncertain.
“The flake was an incredibly exciting find,” Professor Schreve said. “I had been studying the sediments in the meander bend and my eye was drawn to a pinkish stone on the surface. When I turned it over for a better look, the features of a humanly-struck artefact were immediately apparent.
“By working together with geologists and dating specialists, we have been able to put a secure chronology to this find and shed new light on the behaviour of our most distant ancestors.”