Sea scorpions: The original sea monster

Four hundred and thirty million years ago, long before the evolution of barracudas or sharks, a different kind of predator stalked the primordial seas. The original sea monsters were eurypterids -- better known as sea scorpions.

This illustration shows a sea scorpion attacking an early vertebrate 
[Credit: Nathan Rogers]

Related to both modern scorpions and horseshow crabs, sea scorpions had thin, flexible bodies. Some species also had pinching claws and could grow up to three metres in length. New research by University of Alberta scientists Scott Persons and John Acorn hypothesise that the sea scorpions had another weapon at their disposal: a serrated, slashing tail spine.

Armed and dangerous

"Our study suggests that sea scorpions used their tails, weaponized by their serrated spiny tips, to dispatch their prey," says Scott Persons, paleontologist and lead author on the study.

Sparked by the discovery of a new fossil specimen of the eurypterid Slimonia acuminata, Persons and Acorn make the biomechanical case that these sea scorpions attacked and killed their prey with sidelong strikes of their serrated tail.

The fossil, collected from the Patrick Burn Formation near Lesmahagow, Scotland, shows a eurypterid Slimonia acuminata, with a serrated-spine-tipped tail curved strongly to one side.

Powerful weapons

Unlike lobsters and shrimps, which can flip their broad tails up and down to help them swim, eurypterid tails were vertically inflexible but horizontally highly mobile.

"This means that these sea scorpions could slash their tails from side to side, meeting little hydraulic resistance and without propelling themselves away from an intended target," explains Persons. "Perhaps clutching their prey with their sharp front limbs eurypterids could kill pretty using a horizontal slashing motion."

Among the likely prey of Slimonia acuminata and other eurypterids were ancient early vertebrates.

The paper was published in The American Naturalist.

Author: Katie Willis | Source: University of Alberta [April 18, 2017]

byUnknown

in Canada, Fossils, Palaeontology

April 18, 2017

Sea scorpions: The original sea monster

Four hundred and thirty million years ago, long before the evolution of barracudas or sharks, a different kind of predator stalked the primo...

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Megafaunal extinctions driven by too much moisture

Studies of bones from Ice Age megafaunal animals across Eurasia and the Americas have revealed that major increases in environmental moisture occurred just before many species suddenly became extinct around 11-15,000 years ago. The persistent moisture resulting from melting permafrost and glaciers caused widespread glacial-age grasslands to be rapidly replaced by peatlands and bogs, fragmenting populations of large herbivore grazers.

Alan Cooper inspects ice age bones from the Yukon Palaeontology Program’s collection, Canada, 2015 
[Credit: Julien Soubrier]

Research led by the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, published in Nature Ecology and Evolution, has revealed that the ancient bones preserve direct biochemical evidence of the environmental upheavals, which can be traced through time.

Using 511 radiocarbon dated bones from animals such as bison, horse, and llamas the team was able to investigate the role of environmental change in the mysterious megafaunal extinctions, which claimed the vast majority of existing large land animals such as giant sloths and sabre-toothed cats.

Lead Author Tim Rabanus-Wallace hunts for megafaunal fossils in the Canadian permafrost in 2015 
[Credit: Julien Soubrier]

"We didn't expect to find such clear signals of moisture increases occurring so widely across all of Europe, Siberia and the Americas," says study leader Professor Alan Cooper, ACAD Director. "The timing varied between regions, but matches the collapse of glaciers and permafrost and occurs just before most species go extinct.

The international team of researchers, including the University of Alaska Fairbanks, University of Oslo, the Yukon Government, and palaeontologists across Russia and Canada, measured nitrogen isotopes preserved in dated ancient animal bones and teeth recovered from permafrost areas and caves across Europe, Siberia, North and South America. They found distinctive biochemical signals reflecting massive increases of moisture on the landscape.

The study shows that a peak in moisture occurred between the time of the ice sheets melting, and the invasion 
of new vegetation types such as peatlands (data shown from Canada and northern United States)
[Credit: Julien Soubrier]

"Grassland megafauna were critical to the food chains. They acted like giant pumps that shifted nutrients around the landscape," says lead author Dr Tim Rabanus-Wallace, from the University of Adelaide. "When the moisture influx pushed forests and tundras to replace the grasslands, the ecosystem collapsed and took many of the megafauna with it."

"The idea of moisture-driven extinctions is really exciting because it can also explain why Africa is so different, with a much lower rate of megafaunal extinctions and many species surviving to this day,, says Professor Cooper. "Africa's position across the equator means that grassland zones have always surrounded the central monsoon region. The stable grasslands are what has allowed large herbivores to persist -- rather than any special wariness of hunters learned from humans evolving there."

The head of Blue Babe, a mummified ice age bison, rests recently in a lab at the University of Alaska Museum 
of the North. The bison, uncovered near Fairbanks in 1979, was first described by Dale Guthrie, now
 professor emeritus. Most of Blue Babe's skin was preserved and is now publicly displayed on a
 model at the museum, but the head and horns were kept frozen. Professor Matthew Wooller
 and others are now analyzing them to improve our understanding of Blue Babe's environment.
The work includes extraction of collagen from the bones for nitrogen isotope analysis 
[Credit: Matthew Wooller]

Professor Matthew Wooller, of the University of Alaska Fairbanks, says: "We find that on different continents the climate changes happened at different times, but they all showed that moisture increased massively just prior to extinction. The really elegant feature of this study is that it produces direct evidence from the fossils themselves -- these extinct creatures are informing us about the climate they experienced leading up to their own extinctions."

Source: University of Adelaide [April 18, 2017]

byUnknown

in Ancient Environment, Canada, Early Mammals, Earth Science, Fossils, Palaeontology

April 18, 2017

Megafaunal extinctions driven by too much moisture

Studies of bones from Ice Age megafaunal animals across Eurasia and the Americas have revealed that major increases in environmental moistur...

Read More

Retreating Yukon glacier caused a river to disappear

The massive Kaskawulsh Glacier in northern Canada has retreated about a mile up its valley over the past century.

A Sept. 2, 2016 aerial photo shows the meltwater stream along the toe of Kaskawulsh Glacier, seen on the left, that is 
diverting fresh water from one river to the other [Credit: Dan Shugar/University of Washington Tacoma]

Last spring, its retreat triggered a geologic event at relatively breakneck speed. The toe of ice that was sending meltwater toward the Slims River and then north to the Bering Sea retreated so far that the water changed course, joining the Kaskawulsh River and flowing south toward the Gulf of Alaska.

This capture of one river's flow by another, documented in a study led by the University of Washington Tacoma and published in Nature Geoscience, is the first known case of "river piracy" in modern times. "Geologists have seen river piracy, but nobody to our knowledge has documented it happening in our lifetimes," said lead author Dan Shugar, a geoscientist at the University of Washington Tacoma. "People had looked at the geological record -- thousands or millions of years ago -- not the 21st century, where it's happening under our noses."

River piracy, also known as stream capture, can happen due to tectonic motion of Earth's crust, landslides, erosion or, in this case, changes in a glacial dam. The new study documents one of the less-anticipated shifts that can occur in a changing climate.

Shugar and co-authors Jim Best at the University of Illinois and John Clague at Canada's Simon Fraser University had planned fieldwork last summer on the Slims River, a geologically active system that feeds Kluane Lake in the Yukon. When they arrived in August, the river was not flowing. River gauges show an abrupt drop over four days from May 26 to 29, 2016.

By late summer, "there was barely any flow whatsoever. It was essentially a long, skinny lake," Shugar said. "The water was somewhat treacherous to approach, because you're walking on these old river sediments that were really goopy and would suck you in. And day by day we could see the water level dropping."

Images captured by the European Space Agency’s Sentinel2 satellite in 2015 and 2016 show a dramatic drop in the Slims 
River’s flow. The receding toe of Kaskawulsh Glacier is seen at the bottom. Kluane Lake can be seen at the top of the 
2016 image. Water now flows east and then south via the Kaskawulsh River [Credit: European Space Agency]

The research team puzzled about what to do next. They got permission to use their mapping drone to create a detailed elevation model of the glacier tongue and headwater region. The resulting paper is a geological postmortem of the river's disappearance.

"For the last 300 years, Slims River flowed out to the Bering Sea, and the smaller Kaskawulsh River flowed to the Gulf of Alaska. What we found was the glacial lake that fed Slims River had actually changed its outlet," Shugar said. "A 30-meter (100-foot) canyon had been carved through the terminus of the glacier. Meltwater was flowing through that canyon from one lake into another glacial lake, almost like when you see champagne poured into glasses that are stacked in a pyramid."

That second lake drains via the Kaskawulsh River in a different direction than the first. The situation is fairly unique, Shugar said, since the glacier's toe was sitting on a geologic divide.

Clague began studying this glacier years ago for the Geological Survey of Canada. He observed that Kluane Lake, which is Yukon's largest lake, had changed its water level by about 40 feet (12 meters) a few centuries ago. He concluded that the Slims River that feeds it had appeared as the glacier advanced, and a decade ago predicted the river would disappear again as the glacier retreated.

"The event is a bit idiosyncratic, given the peculiar geographic situation in which it happened, but in a broader sense it highlights the huge changes that glaciers are undergoing around the world due to climate change," Clague said.

A close-up view of the ice-walled canyon at the terminus of the Kaskawulsh Glacier, with recently collapsed ice blocks. 
This canyon now carries almost all meltwater from the toe of the glacier down the Kaskawulsh Valley 
and toward the Gulf of Alaska [Credit: Jim Best/University of Illinois]

The geologic event has redrawn the local landscape. Slims River crosses the Alaska Highway, and its banks were a popular hiking route. Now that the riverbed is exposed, Dall sheep from Kluane National Park are making their way down to eat the fresh vegetation, venturing into territory where they can legally be hunted. With less water flowing in, Kluane Lake did not refill last spring, and by summer 2016 was about 3 feet (1 meter) lower than ever recorded for that time of year. Waterfront land, which includes the small communities of Burwash Landing and Destruction Bay, is now farther from shore. As the lake level continues to drop researchers expect this will become an isolated lake cut off from any outflow.

On the other hand, the Alsek River, a popular whitewater rafting river that is a UNESCO world heritage site, was running higher last summer due to the addition of the Slims River's water.

Shifts in sediment transport, lake chemistry, fish populations, wildlife behavior and other factors will continue to occur as the ecosystem adjusts to the new reality, Shugar said.

"So far, a lot of the scientific work surrounding glaciers and climate change has been focused on sea-level rise," Shugar said. "Our study shows there may be other underappreciated, unanticipated effects of glacial retreat."

The Kaskawulsh Glacier is retreating up the valley because of both readjustment after a cold period centuries ago, known as the Little Ice Age, and warming due to greenhouse gases. A technique published in 2016 by UW co-author Gerard Roe shows a 99.5 percent probability that this glacier's retreat is showing the effects of modern climate change.

"I always point out to climate-change skeptics that Earth's glaciers are becoming markedly smaller, and that can only happen in a warming climate," Clague said.

Source: University of Washington [April 17, 2017]

byUnknown

in Canada, Climate Change, Ecosystems, Natural Heritage, North America

April 17, 2017

Retreating Yukon glacier caused a river to disappear

The massive Kaskawulsh Glacier in northern Canada has retreated about a mile up its valley over the past century. A Sept. 2, 2016 aerial pho...

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Paleontologists reappraise description of duck billed hadrosaurs

The duck-billed dinosaurs (hadrosaurs) may not be as glamorous as tyrannosaurs (and most tyrannosaur researchers sure don't respect these "Cretaceous food items" anyhow), but in many ways they are a far more interesting and scientifically viable group to study.

Skull of Edmontosaurus regalis [Credit: Xing et al. 2017]

Hadrosaurs are known from literally tons of fossils from around the world, often with nearly complete skeletons and frequent soft-tissue preservation. As a result, you can answer a lot of research questions with hadrosaurs that are difficult to address with more rare groups.

But, surprisingly (or perhaps not surprisingly, given many people's inexplicable preference for the sharp-in-tooth-and-claw tyrannosaurs), lots of basic research on hadrosaurs remains. This is a golden opportunity for scientists!

In many ways, Edmontosaurus is the archetype of hadrosaurs. Their fossils, abundant in North American rocks from around 72 to 66 million years old, are on display in numerous museums and have consequently been featured in toys and on television alike.

Early researchers, beginning in the first half of the 20th century, lavishly described and illustrated many of these specimens in the scientific literature. Yet, that grand tradition of detailed description has fallen somewhat fallow. We as scientists are often happy to rest on the laurels of our predecessors. If Edmontosaurus was already well-described back in 1920, what's the point in doing it again?

As paleontologists learn more about the anatomy and evolution of hadrosaurs, it's readily apparent that earlier workers didn't even know to bother describing, comparing, and illustrating certain features.

This is not their fault, of course–different aspects of anatomy are considered more relevant at different times. As additional species are uncovered or as old species are invalidated, the importance of some anatomical details is elevated, and that of other details is decreased. So, it never hurts to revisit "old" and well-described fossils.

Skeletal reconstruction of Edmontosaurus regalis [Credit: Xing et al. 2017]

A new paper by Hai Xing and colleagues redescribes skulls of the original Edmontosaurus species, Edmontosaurus regalis. Uncovered in Upper Cretaceous rocks of Alberta, over a dozen pretty decent crania, partial skeletons, and many fragments are known.

Edmontosaurus as a genus was recently revised, showing that many things previously lumped into various species and genera (including the old classics Anatosaurus and Anatotitan) were likely just two species of Edmontosaurus: E. regalis (the earlier Canadian form) and E. annectens (the later form found in both Canada and the United States).

An Alaskan form, Ugrunaaluk, was considered to be closely related. So, with all of the family tree stuff sorted out, now is a good time to review the variation within Edmontosaurus regalis and describe some newly relevant (and previously unrecognized) anatomical details.

The paper, published last week in PLOS ONE, provides detailed illustrations and text descriptions for numerous details on the skull in Edmontosaurus regalis. Once the anatomical work was out of the way, the authors re-evaluated previously proposed differences with the sister species E. annectens, and were able to add several formerly unrecognized features that can help separate the two species.

Next, a comprehensive analysis produced a new family tree, which was broadly similar to previously published versions but also had a few interesting adjustments. For instance, an animal from Alabama called Eotrachodon was found to fall outside of the main group of "true" hadrosaurids (rather than within the group as previously proposed). A number of other slight readjustments also appeared in the analysis, all of which have relevance for how hadrosaurs spread across the surface of the globe during their evolution.

Finally, restudy of Edmontosaurus regalis indicates a potential shake-up for the Alaskan duck-bill Ugrunaaluk. Ugrunaaluk is known from numerous specimens, but they are all juveniles. Xing and colleagues note many similarities between Ugrunaaluk and Edmontosaurus regalis–enough that they may even be the same species.

Frustratingly, though, no juveniles of E. regalis are known at a size similar to those for Ugrunaaluk, meaning that equivalent life stages from the animals can't be compared directly. So, we're back to the classic refrain: we need more fossils to know for sure!

Author: Andrew Farke | Source: PLOS Blogs [April 12, 2017]

byUnknown

in Canada, Dinosaurs, Fossils, Palaeontology

April 12, 2017

Paleontologists reappraise description of duck billed hadrosaurs

The duck-billed dinosaurs (hadrosaurs) may not be as glamorous as tyrannosaurs (and most tyrannosaur researchers sure don't respect thes...

Read More

Archaeologists unearth ancient pithouse in British Columbia's Fraser Canyon

An ancient pithouse at Bridge River in the Fraser Canyon that spanned about 1,500 years and included 17 distinct layered floors ending at the European fur-trade era is providing unique insight into the lives of early First Nations, archaeological research reveals.

A new archaeology study is revealing fantastic details about an aboriginal pithouse at Bridge River 
in the Fraser Canyon spanning about 1,500 years and including 17 distinct layered floors 
ending at the European fur-trade era [Credit: PNG]

“For the entire Pacific Northwest region, this is the best documented, long-lived aboriginal house in the archaeological record,” confirmed Anna Marie Prentiss, a professor of anthropology at the University of Montana in Missoula. “We have exquisite detail, with all these floors.”

About every 20 years, the Bridge River people built a new roof on the pithouse and a new layer of dirt floor as a living area. Each layer or floor reveals details specific to that time period, be it the rise and fall of salmon stocks, the creation of artwork such as pendants, the trade in iron and beads, the processing of deer pelts, even the raising of domestic dogs for human consumption.

The excavation site is about two kilometres upstream of the Fraser River confluence next to the current Bridge River village. Band chief Susan James says her people — 457 members, about half of them living on reserve — had a general knowledge of their ancestors but not to the level of detail unveiled by archaeologists. “We’ve found it fascinating, it’s all been learning for us,” she said. Band tours of the site are available to the public.

Prentiss explained that Pithouse 54 was excavated over four seasons. Her book, The Last House at Bridge River, is about to be published.

“We realized this house had something special, an extraordinary record,” she said.

The dig found 157 dog bones on various floors, several featuring cut marks from defleshing. Although the Bridge River dog is related to Siberian dogs, it was considered its own unique breed. The thinking is that younger dogs up to 2.5 years old risked being eaten. Older dogs were typically kept as family pets and for work, including for transport and as a warning system for the village.

Dogs were also thought to be a delicacy at Bridge River, said Prentiss, who obtained her doctoral degree from Simon Fraser University. “When (explorer) Simon Fraser visited the Lillooet people (1808) he was served a feast of dog meat. That kind of says it all right there.”

The pithouse was not occupied consecutively for 1,500 years. It was abandoned three times, including about 1,000 years ago. A decline in salmon bones suggest fewer fish migrating through the Fraser Canyon during an era known as the Medieval Warm Period.

The house also expanded in size and shape, at times rectangular or round, over the generations. At its peak, it might have housed 30-40 people.

Pithouses were badgered into the ground to provide extra warmth in winter and cooling in summer, reflecting the more extreme climates of the Lillooet area.

The top layer of the pithouse is thought to span the late fur-trading period from 1835 to 1858. Researchers found numerous artifacts of the period, including: Venetian glass beads painted red, green and white; an iron horseshoe; a finger ring; machine-made bone buttons; and three stone spindle whorls, suggesting weaving yarn from dog or mountain goat hair.

Researchers also found heaps of deer bones, burned rocks from boiling, 250 hide scrapers, and 135 stone arrow points, evidence that aboriginals were trading skins with fur traders, a period when beaver populations had collapsed.

“The fur-trade material lets us see what life was like just before the onslaught of the gold rush,” Prentiss says. “We’ve never had that kind of insight.”

The pithouse, which is part of a larger settlement, contains no evidence from the gold-rush starting in 1858 in the area, she said. After that, aboriginals are thought to have lived in cabins.

Prentiss is presenting her findings at the Society for American Archaeology conference, which opens Wednesday in Vancouver and is expected to attract 5,000 visitors through this weekend.

Author: Larry Pynn | Source: Vancouver Sun [April 07, 2017]

byUnknown

in Americas, Archaeology, Canada, Indigenous Cultures, North America

April 07, 2017

Archaeologists unearth ancient pithouse in British Columbia's Fraser Canyon

An ancient pithouse at Bridge River in the Fraser Canyon that spanned about 1,500 years and included 17 distinct layered floors ending at th...

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Study reveals 10,000 years of genetic continuity in northwest North America

A study of the DNA in ancient skeletal remains adds to the evidence that indigenous groups living today in southern Alaska and the western coast of British Columbia are descendants of the first humans to make their home in northwest North America more than 10,000 years ago.

Researchers are analyzing DNA from ancient individuals found in southeast Alaska, coastal British Columbia, Washington
state and Montana. A new genetic analysis of some of these human remains finds that many of today's indigenous peoples 
living in the same regions are descendants of ancient individuals dating to at least 10,300 years ago 
[Credit: Julie McMahon, University of Illinois]

"Our analysis suggests that this is the same population living in this part of the world over time, so we have genetic continuity from 10,000 years ago to the present," said University of Illinois anthropology professor Ripan Malhi, who led the study with University of Chicago postdoctoral researcher John Lindo; Penn State University biology professor Michael DeGiorgio; Rosita Worl, the director of the Sealaska Heritage Institute in Juneau, Alaska; and University of Oklahoma anthropology professor Brian M. Kemp.

The findings, reported in the Proceedings of the National Academy of Sciences, also suggest that these early American peoples had a complex population history, the researchers report.

The new work comes on the heels of earlier studies of ancient Americans that focused on mitochondrial DNA, which occurs outside the nucleus of cells and is passed only from mothers to their offspring.

"Mitochondrial DNA just traces the maternal line - your mother's mother's lineage - so, you're missing information about all of these other ancestors," said Lindo, the first author on the paper. "We wanted to analyze the nuclear genome so we could get a better assessment of the population history of this region."

The team looked at genomic data from Shuká Káa (Tlingit for "Man Before Us"), an ancient individual whose remains - found in a cave in southeastern Alaska - date to about 10,300 years ago. They also analyzed the genomes of three more individuals from the nearby coast of British Columbia whose remains date to between 6,075 and 1,750 years ago.

"Interestingly, the mitochondrial type that Shuká Káa belonged to was also observed from another ancient skeleton dated to about 6,000 years ago," Kemp said. "It seems to disappear after that. The nuclear DNA suggests that this is probably not about population replacement, but rather chance occurrence through time. If a female has no children or only sons, the mitochondrial DNA is not passed to the next generation. As a male, Shuká Káa could not have passed on his own mitochondrial DNA; he must have had some maternal relatives that did so."

The researchers turned their attention to nuclear DNA, which offers a more comprehensive record of a person's ancestry.

"DNA from the mitochondria and Y chromosome provide unique yet sometimes conflicting stories, but the nuclear genome provides a more comprehensive view of past events," DeGiorgio said.

"The data suggest that there were multiple genetic lineages in the Americas from at least 10,300 years ago," Malhi said.

The descendants of some of those lineages are still living in the same region today, and a few are co-authors on the new study. Their participation is the result of a long-term collaboration between the scientists and several native groups who are embracing genomic studies as a way to learn from their ancestors, said Worl, who is Tlingit, Ch'áak' (Eagle) moiety of the Shangukeidí­ (Thunderbird) Clan from the Kawdliyaayi Hít (House Lowered From the Sun) in Klukwan, Alaska.

"We supported DNA testing of Shuká Káa because we believed science ultimately would agree with what our oral traditions have always said - that we have lived in southeast Alaska since time immemorial. The initial analysis showed the young man was native, and now further studies are showing that our ancestral lineage stems from the first initial peopling of the region," said Worl, who also is an anthropologist. "Science is corroborating our oral histories."

Author: Diana Yates | Source: University of Illinois at Urbana-Champaign [April 04, 2017]

byUnknown

in Americas, Anthropology, Canada, Genetics, Indigenous Cultures, North America, USA

April 04, 2017

Study reveals 10,000 years of genetic continuity in northwest North America

A study of the DNA in ancient skeletal remains adds to the evidence that indigenous groups living today in southern Alaska and the western c...

Read More

Archaeologist explains innovation of 'fluting' ancient stone weaponry

Approximately 13,500 years after nomadic Clovis hunters crossed the frozen land bridge from Asia to North America, researchers are still asking questions and putting together clues as to how they not only survived in a new landscape with unique new challenges but adapted with stone tools and weapons to thrive for thousands of years.

A collection of Clovis point replicas and casts in the archaeology lab at Kent State University
[Credit: Kent State University]

Kent State University's Metin Eren, Ph.D., director of archaeology and assistant professor in the Department of Anthropology in the College of Arts and Sciences, and his colleagues are not only asking these questions but testing their unique new theories. They want to better understand the engineering, techniques and purposes of Clovis weapon technologies. Specifically, they study stone projectile points, such as arrowheads and spear points, made by flint knapping, the ancient practice of chipping away at the edges of rocks to shape them into weapons and tools.

In their most recent article published online in the Journal of Archaeological Science, Eren and his co-authors from Southern Methodist University (Brett A. Story, David J. Meltzer and Kaitlyn A. Thomas), University of Tulsa (Briggs Buchanan), Rogers State University (Brian N. Andrews), Texas A&M University and the University of Missouri (Michael J. O'Brien) explain the flint knapping technique of "fluting" the Clovis points, which could be considered the first truly American invention. This singular technological attribute, the flake removal or "flute," is absent from the stone-tool repertoire of Pleistocene Northeast Asia, where the Clovis ancestors came from.

Metin Eren, director of archaeology and an assistant professor of anthropology in Kent State University's College of Arts 
and Sciences, demonstrates the ancient weapon-making technique of flint knapping a point in his laboratory 
on the Kent Campus [Credit: Kent State University]

Archaeologists have debated for years as to why the Clovis added this flute feature to their points. Basically, it is a thin groove chipped off at the base on both sides, perhaps first made by accident, which logically makes it very thin and brittle. However, after several types of testing, the researchers have reported that this thinning of the base can make it better able to withstand and absorb the shock of colliding with a hard object, such as the bone of a mastodon or bison.

This fluted point turned out to be an invention that allowed these colonizers to travel great distances with some confidence that their weaponry would hold up at least long enough until they could find the next rock quarry to make new points.

"It was risky and couldn't have been easy to learn how to do this effectively," Eren explained. "Archaeological evidence suggests that up to one out of five points break when you try to chip this fluted base, and it takes at least 30 minutes to produce a finished specimen. So, though it was a time-consuming process and risky technique, successfully fluted Clovis points would have been extremely reliable, especially while traveling great distances into unknown regions on a new continent. They needed points that would hold up and be used over and over again."

In their article, the researchers compared standardized computer models of fluted and unfluted points, as well as experimental "real-world" test specimens, and found that the fluted-point base does in fact act as a "shock absorber," increasing point robustness and ability to withstand physical stress via stress redistribution and damage relocation. In other words, upon impact, the brittle base of the spearhead crumples and absorbs some energy, which prevents fatal breaks elsewhere on the point so it could be reused.

"It's amazing to think that people 12,000 years ago were flaking shock absorbers and engineering stone weapons in a way that it took 21st century modern engineering to figure out," Eren said.

"As engineers, we don't typically get to work with archaeologists, but this project has allowed us the exciting opportunity to provide additional tools from engineering mechanics to explore how fluting affects the behavior of Clovis points," Story said.

Source: Kent State University [April 04, 2017]

byUnknown

in Americas, Archaeology, Canada, North America, USA

April 04, 2017

Archaeologist explains innovation of 'fluting' ancient stone weaponry

Approximately 13,500 years after nomadic Clovis hunters crossed the frozen land bridge from Asia to North America, researchers are still ask...

Read More