USER
your role is tunisian arabic dailctic derja transltor Translate the following text into the Tunisian dialect. Ensure the output is structured as 'Question: ... Answer: ...'. Please capture the nuances of the Tunisian dialectic Arabic. make sure type and write in arabic tunisian lettre Here is an example to guide you:
Question: شنو اسمك؟
Answer: اسمي جون.
Now, translate the following:
Question: News article:
A 22-foot beaked whale that apparently took a wrong turn up an African river about 17 million years ago may offer clues to the climate-change forces that shaped human evolution.
Lost for more than 30 years, the fossilized beak with part of the jaw bone helps determine that the East African Plateau probably began rising no earlier than 17 million years ago, according to a study published online Monday in the journal Proceedings of the National Academy of Sciences.
That geologic upheaval in an area known as the cradle of humankind is believed to be responsible for the gradual conversion of dense, humid forests into more sparsely treed grasslands that made upright locomotion on two feet advantageous to evolving human ancestors.
"The whale is telling us all kinds of things," said study coauthor Louis Jacobs, a paleontologist at Southern Methodist University in Dallas. "It tells us the starting point for all that uplift that changed the climate that led to humans. It’s amazing.”
Jacobs had been searching for the specimen since 1980, when he was head of paleontology at the National Museums of Kenya. He had read about the 1964 find, by James G. Mead of the Smithsonian Institution, in a 1975 research paper.
Every time Jacobs visited Harvard, Washington or Nairobi, he would try to find it.
"It was protected by a plaster jacket, so you couldn’t really see it," he said. “I suspect nobody knew what it was. It was just kept in the collections there.”
Finally, just before another trip to Kenya in 2011, a collections official at Harvard located the fossil, sheathed in the protective jacket, Jacobs said.
Jacobs had the specimen scanned and analyzed, then contacted Henry Wichura, a structural geologist at the University of Potsdam in Germany, who had been studying plateau region, trying to determine when it started rising. He had found evidence that rivers and lava had flowed east from high points on the plateau at least 13 million years ago.
“What was missing was geological evidence of the onset" of uplift, Wichura said. "That doesn’t exist in this area, not in the normal geological sense.”
That's because the area is being shaped by multiple forces. A hot spot in Earth's mantle has been pushing up a wide area of East Africa, while rifts from tectonic forces have been fracturing the crust. That doesn't bode well for fossils in sedimentary rocks.
The researchers used Mead's original field notes to pinpoint where the fossil had been excavated, and at what elevation -- more than 2,000 feet above modern sea level. Then they looked up incidents of whales swimming upriver from the sea.
"That river had to be a large river with a low gradient and it had to swim a long way up," Jacobs said.
No whale had swum to anywhere close to such an elevation. Even the Antarctic minke that took the longest known detour, more than 600 miles up the Amazon and its tributary, the Tapajos, reached an elevation of little more than 3 feet above the Atlantic Ocean. A humpback whale, dubbed Humphrey, twice swam a more modest 82 miles up the Sacramento River. Freshwater dolphins have been found at elevations of more than 300 feet in Peru.
Those detours or strandings occurred in relatively deep river systems that fell by a maximum of 1.1 inches per mile, the study found.
Based on the sea level and shape of the African coast at the time, the whale would have traveled 372 to 559 miles from the Indian Ocean, bringing it to an elevation of 78 to 121 feet, according to the study. So, the area must have risen at least 1,935 feet to reach its present elevation, the authors estimate.
The whale bone was found in a thick layer of sediment beneath a lava flow dated to 17 million years old, according to the study. Around it were mammal fossils that date to a period when Africa and Eurasia were joined.
“We knew it had to be after the big exchange between Eurasia and Africa, when elephants left Africa, and when carnivores and various kinds of hoofed animals came in," 23 million years ago, Jacobs said. Because the fossil was located closer to the border of the 17-million-year-old basalt flow, researchers concluded that uplift could not have started any earlier.
Fossil and geologic evidence correlate that uplift with a long-term drying of the local climate, which changed a humid forest into grasslands with more widely spaced trees. Scientists theorize that this kind of environmental pressure favored primates that could straighten their back and walk longer distance on two feet, leading to the radiation into species that led to modern humans.
The chances that one such modern human, Mead, would find a fossilized bone from an errant marine mammal, buried under the desert, are astonishingly slim. "It's an amazing thing," Jacobs said. "But there it is."
Although such a find so far inland may seem to defy logic, "there is really no better answer that I can see than the one they present," said Eric M. Roberts, a geologist at James Cook University in Australia who studies the same region.
Roberts cautioned that recent work in the rift zone where the fossil was discovered suggests older fossils may have been mixed up in younger sediments. Although there is no evidence that this occurred, he added, "it is something that must be considered since the original site is still unknown."
Astonished by science? Follow me on Twitter: @LATsciguy ||||| CAMBRIDGE, Mass., March 17 (UPI) -- Prehistorians believe the transition from dense, elevated forest to flat, open grasslands in East Africa spurred humans' ancestors to first abandon all fours and walk upright. But when exactly did this happen? Researchers say a long lost beaked whale fossil may offer clues.
Though the beaked whale fossil in question is only just now making headlines, it was first discovered in Kenya in 1964. It was unearthed some 460 miles inland, suggesting the sea mammal had gotten lost and swam up a freshwater river system. But the 17-million-year-old fossil was originally misidentified as a turtle, and little analysis was conducted before it went missing.
It stayed lost in the archives of Harvard University for nearly 40 years, before Louis Jacobs -- who knew of its existence but for years failed to locate the fossil -- finally found the skull.
While the whale's journey inland is fascinating in itself, the fossil's rediscovery has offered much grander scientific revelations. The skull has helped researchers to date the East African plateau's uplift, and thus allowed scientists to more accurately pinpoint the place and time when human bipedalism first emerged.
"The whale is telling us all kinds of things," study co-author Louis Jacobs, a paleontologist at Southern Methodist University in Dallas, told the Los Angeles Times. "It tells us the starting point for all that uplift that changed the climate that led to humans. It's amazing."
To date and measure the plateau's uplift, scientists used the original field notes to relocate the site of fossil's initial discovery. Next researchers looked at evidence of modern whales and dolphins who became lost upriver. Because they knew whales could only travel up a wide, low-gradient river, scientists were able to estimate the nature of the ancient waterway. Their analysis suggested the original site of whale's death (likely from exhaustion) couldn't have been more than 372 to 559 miles from the Indian Ocean and nor more than 78 to 121 feet high.
Today, that same spot is more than 2,000 feet above sea level, meaning uplifting forces from a plume of magma in the Earth's mantle has caused some 1,935 feet of rise in the 17 million years since the whale's fateful end.
"At the time when the whale stranded, it was assumed that there was a pan-African rainforest across the entire area," lead study author Henry Wichura, a geoscientist at the University of Potsdam, in Germany, told Australia's ABC Science.
Wichura is an expert on the plateau's uplift and ancient climate change in East Africa. But a more accurate date on the start of East Africa's uplifting suggests the transition from forest to grasslands began sooner than previously thought -- the climate change that first made walking on two feet advantageous.
"Even single specimens of organisms tell us a great deal about the history of the Earth, and they sometimes appear in surprising cases," Frank Brown, a geologist at the University of Utah who was not involved in the study, told Live Science. "This is one such case."
The new study was published in the journal PNAS this week. ||||| An enigmatic fossil representing the deep-diving, open-ocean whale family Ziphiidae found 740 km inland and at 620 m elevation in West Turkana, Kenya was rediscovered after it went missing for more than 30 years. This stranded whale fossil provides the first constraint on the initiation of east African uplift from near sea level at 17 Ma, limiting the timing and initial elevation of environmental change indicated by geodynamic and climatic modeling, paleosols, isotopes, paleobotany, and the mammalian fossil record. At 17 Ma, elevation was low, rainfall was high, vegetation was forested, and mammalian communities contained immigrants and native African species, including diverse primates. Uplift resulted in increasing aridity and open habitats that drove human evolution.
Abstract
Timing and magnitude of surface uplift are key to understanding the impact of crustal deformation and topographic growth on atmospheric circulation, environmental conditions, and surface processes. Uplift of the East African Plateau is linked to mantle processes, but paleoaltimetry data are too scarce to constrain plateau evolution and subsequent vertical motions associated with rifting. Here, we assess the paleotopographic implications of a beaked whale fossil (Ziphiidae) from the Turkana region of Kenya found 740 km inland from the present-day coastline of the Indian Ocean at an elevation of 620 m. The specimen is ∼17 My old and represents the oldest derived beaked whale known, consistent with molecular estimates of the emergence of modern strap-toothed whales (Mesoplodon). The whale traveled from the Indian Ocean inland along an eastward-directed drainage system controlled by the Cretaceous Anza Graben and was stranded slightly above sea level. Surface uplift from near sea level coincides with paleoclimatic change from a humid environment to highly variable and much drier conditions, which altered biotic communities and drove evolution in east Africa, including that of primates. ||||| A 17-million-year-old beaked whale fossil is helping researchers solve a puzzle about the likely birthplace of humanity in East Africa, a new study finds.
The whale (Ziphiidae) lived when the East African plateau was substantially lower and covered by dense forests, the researchers said. Scientists have long tried to figure out when the uplift occurred, because when it did, the moisture from the Indian Ocean could no longer reach the trees and vegetation, and the area turned into a savannah, research suggests.
Extinct ancestors to modern humans may have lived in trees in East Africa, but after the area turned into grassland, these early humans gradually began walking on two feet, researchers suggest. [Top 10 Mysteries of the First Humans]
"It's more or less the story about the bipedalism," said study researcher Henry Wichura, a postdoctoral candidate in geoscience at University of Potsdam in Germany.
But the timing of the East African plateau uplift has eluded scientists. The whale fossil helps researchers get closer to that date, which likely occurred sometime between 17 million and 13.5 million years ago, according to the new study.
A whale of a tale
The story of the whale skull is one of rediscovery. Researchers originally found the fossil in 1964, but didn't publish a study on it until 1975. Then, they misplaced the skull until 2011.
The skull is the oldest known fossil of a beaked whale, and it confounded researchers at first. Beaked whales are deep divers that live in the ocean, but the fossil was found 460 miles (740 kilometers) inland from the present-day East African coast, and at an elevation of 2,100 feet (640 meters).
Perhaps the 23-foot-long (7 m) whale used to live in the Indian Ocean, but mistakenly strayed into a river that led it into modern-day Kenya, the study researchers said.
Researcher James Mead, as he uncovered the whale fossil in Loperot, Kenya, in 1964. Credit: Image courtesy of James G. Mead
"We came to the idea that it used a large river system, because the whale had been found in lake sediments which are [mixed with] river sediments," Wichura said. "So we can say that it died in a kind of river-lake environment."
But the fossil sat unstudied for nearly 40 years, until researchers rediscovered it at Harvard University. (Interestingly, a curator found the fossil in the former office of renowned paleontologist Stephen Jay Gould. At the time, the university was using Gould's office for temporary storage during a remodel, according to the study.)
Once recovered, the skull helped Wichura and his colleagues date the East African plateau's uplift. They wondered how low the East African plateau was before the region's topography changed, so they searched for other instances of whales getting lost in rivers. For instance, one whale became stranded in the Thames River in 2006, and killer whales have swum into the Columbia River in the Pacific Northwest of the United States.
The scientists took the grade of the steepest river from case reports, and applied it to the prehistoric river used by the whale. So, if the ancient river rose at 2.5 inches a mile (4 centimeters per km) from the coast, the East African plateau was between 79 feet and 121 feet high (24 m and 37 m) at the time the whale lost its way and died. (The difference in height takes into account the different routes the whale may have taken to swim inland from the Indian Ocean.)
Considering that the plateau is now about 2,034 feet (620 m) tall, the northern part of the Eastern African plateau must have been uplifted by about 1,925 feet (590 m) over the past 17 million years, the researchers determined.
Furthermore, Wichura found that at 13.5 million years ago, part of the Eastern African plateau uplift had already begun, putting a bookend on when the uplift started. (He noted that the uplift happened because of mantle plumes, hot material that rises through the Earth's mantle and pushes up against the crust.)
Without the rediscovered skull, it would have been difficult to help date the uplift, he said.
"With the whale, everything started," Wichura told Live Science.
The study reminds both professional and amateur paleontologists to study the location and age of each fossil they find, said Frank Brown, a professorof geology at the University of Utah, who was not involved in the study.
"Even single specimens of organisms tell us a great deal about the history of the Earth, and they sometimes appear in surprising cases," Brown said. "This is one such case."
The study was published today (March 16) in the journal Proceedings of the National Academy of Sciences.
Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science. |||||
What is a shorter version of the above article?
Answer: Researchers have discovered a 22-foot beaked whale fossil about 17 million years old that offers important clues about the climate change forces that played a role in human evolution. The fossil, which had been lost for more than 30 years, suggests that the East African Plateau began rising no earlier than 17 million years ago, according to a study published in the journal Proceedings of the National Academy of Sciences. The geologic upheaval in the area, which is known as the cradle of humankind, led to the gradual transformation of dense, humid forests into sparse grasslands that made walking upright advantageous for evolving human ancestors. The whale bone was found in a thick layer of sediment beneath a lava flow that was 17 million years old, according to the study, and around it, mammal fossils date back to a time when Africa and Eurasia were joined. Researchers used this information to conclude that uplift could not have begun before this time.
ASSISTANT
Question: خبر مقالة:
A 22-foot beaked whale that apparently took a wrong turn up an African river about 17 million years ago may offer clues to the climate-change forces that shaped human evolution.
Lost for more than 30 years, the fossilized beak with part of the jaw bone helps determine that the East African Plateau probably began rising no earlier than 17 million years ago, according to a study published online Monday in the journal Proceedings of the National Academy of Sciences.
That geologic upheaval in an area known as the cradle of humankind is believed to be responsible for the gradual conversion of dense, humid forests into more sparsely treed grasslands that made upright locomotion on two feet advantageous to evolving human ancestors.
"The whale is telling us all kinds of things," said study coauthor Louis Jacobs, a paleontologist at Southern Methodist University in Dallas. "It tells us the starting point for all that uplift that changed the climate that led to humans. It’s amazing.”
Jacobs had been searching for the specimen since 1980, when he was head of paleontology at the National Museums of Kenya. He had read about the 1964 find, by James G. Mead of the Smithsonian Institution, in a 1975 research paper.
Every time Jacobs visited Harvard, Washington or Nairobi, he would try to find it.
"It was protected by a plaster jacket, so you couldn’t really see it," he said. “I suspect nobody knew what it was. It was just kept in the collections there."
Finally, just before another trip to Kenya in 2011, a collections official at Harvard located the fossil, sheathed in the protective jacket, Jacobs said.
Jacobs had the specimen scanned and analyzed, then contacted Henry Wichura, a structural geologist at the University of Potsdam in Germany, who had been studying plateau region, trying to determine when it started rising. He had found evidence that rivers and lava had flowed east from high points on the plateau at least 13 million years ago.
“What was missing was geological evidence of the onset" of uplift, Wichura said. "That doesn’t exist in this area, not in the normal geological sense."
That's because the area is being shaped by multiple forces. A hot spot in Earth's mantle has been pushing up a wide area of East Africa, while rifts from tectonic forces have been fracturing the crust. That doesn't bode well for fossils in sedimentary rocks.
The researchers used Mead's original field notes to pinpoint where the fossil had been excavated, and at what elevation -- more than 2,000 feet above modern sea level. Then they looked up incidents of whales swimming upriver from the sea.
"That river had to be a large river with a low gradient and it had to swim a long way up," Jacobs said.
No whale had swum to anywhere close to such an elevation. Even the Antarctic minke that took the longest known detour, more than 600 miles up the Amazon and its tributary, the Tapajos, reached an elevation of little more than 3 feet above the Atlantic Ocean. A humpback whale, dubbed Humphrey, twice swam a more modest 82 miles up the Sacramento River. Freshwater dolphins have been found at elevations of more than 300 feet in Peru.
Those detours or strandings occurred in relatively deep river systems that fell by a maximum of 1.1 inches per mile, the study found.
Based on the sea level and shape of the African coast at the time, the whale would have traveled 372 to 559 miles from the Indian Ocean, bringing it to an elevation of 78 to 121 feet, according to the study. So, the area must have risen at least 1,935 feet to reach its present elevation, the authors estimate.
The whale bone was found in a thick layer of sediment beneath a lava flow dated to 17 million years old, according to the study. Around it were mammal fossils that date to a period when Africa and Eurasia were joined.
“We knew it had to be after the big exchange between Eurasia and Africa, when elephants left Africa, and when carnivores and various kinds of hoofed animals came in," 23 million years ago, Jacobs said. Because the fossil was located closer to the border of the 17-million-year-old basalt flow, researchers concluded that uplift could not have started any earlier.
Fossil and geologic evidence correlate that uplift with a long-term drying of the local climate, which changed a humid forest into grasslands with more widely spaced trees. Scientists theorize that this kind of environmental pressure favored primates that could straighten their back and walk longer distance on two feet, leading to the radiation into species that led to modern humans.
The chances that one such modern human, Mead, would find a fossilized bone from an errant marine mammal, buried under the desert, are astonishingly slim. "It's an amazing thing," Jacobs said. "But there it is."
Although such a find so far inland may seem to defy logic, "there is really no better answer that I can see than the one they present," said Eric M. Roberts, a geologist at James Cook University in Australia who studies the same region.
Roberts cautioned that recent work in the rift zone where the fossil was discovered suggests older fossils may have been mixed up in younger sediments. Although there is no evidence that this occurred, he added, "it is something that must be considered since the original site is still unknown."
Astonished by science? Follow me on Twitter: @LATsciguy ||||| CAMBRIDGE, Mass., March 17 (UPI) -- Prehistorians believe the transition from dense, elevated forest to flat, open grasslands in East Africa spurred humans' ancestors to first abandon all fours and walk upright. But when exactly did this happen? Researchers say a long lost beaked whale fossil may offer clues.
Though the beaked whale fossil in question is only just now making headlines, it was first discovered in Kenya in 1964. It was unearthed some 460 miles inland, suggesting the sea mammal had gotten lost and swam up a freshwater river system. But the 17-million-year-old fossil was originally misidentified as a turtle, and little analysis was conducted before it went missing.
It stayed lost in the archives of Harvard University for nearly 40 years, before Louis Jacobs -- who knew of its existence but for years failed to locate the fossil -- finally found the skull.
While the whale's journey inland is fascinating in itself, the fossil's rediscovery has offered much grander scientific revelations. The skull has helped researchers to date the East African plateau's uplift, and thus allowed scientists to more accurately pinpoint the place and time when human bipedalism first emerged.
"The whale is telling us all kinds of things," study co-author Louis Jacobs, a paleontologist at Southern Methodist University in Dallas, told the Los Angeles Times. "It tells us the starting point for all that uplift that changed the climate that led to humans. It's amazing."
To date and measure the plateau's uplift, scientists used the original field notes to relocate the site of fossil's initial discovery. Next researchers looked at evidence of modern whales and dolphins who became lost upriver. Because they knew whales could only travel up a wide, low-gradient river, scientists were able to estimate the nature of the ancient waterway. Their analysis suggested the original site of whale's death (likely from exhaustion) couldn't have been more than 372 to 559 miles from the Indian Ocean and nor more than 78 to 121 feet high.
Today, that same spot is more than 2,000 feet above sea level, meaning uplifting forces from a plume of magma in the Earth's mantle has caused some 1,935 feet of rise in the 17 million years since the whale's fateful end.
"At the time when the whale stranded, it was assumed that there was a pan-African rainforest across the entire area," lead study author Henry Wichura, a geoscientist at the University of Potsdam, in Germany, told Australia's ABC Science.
Wichura is an expert on the plateau's uplift and ancient climate change in East Africa. But a more accurate date on the start of East Africa's uplifting suggests the transition from forest to grasslands began sooner than previously thought -- the climate change that first made walking on two feet advantageous.
"Even single specimens of organisms tell us a great deal about the history of the Earth, and they sometimes appear in surprising cases," Frank Brown, a geologist at the University of Utah who was not involved in the study, told Live Science. "This is one such case."
The new study was published in the journal PNAS this week. ||||| An enigmatic fossil representing the deep-diving, open-ocean whale family Ziphiidae found 740 km inland and at 620 m elevation in West Turkana, Kenya was rediscovered after it went missing for more than 30 years. This stranded whale fossil provides the first constraint on the initiation of east African uplift from near sea level at 17 Ma, limiting the timing and initial elevation of environmental change indicated by geodynamic and climatic modeling, paleosols, isotopes, paleobotany, and the mammalian fossil record. At 17 Ma, elevation was low, rainfall was high, vegetation was forested, and mammalian communities contained immigrants and native African species, including diverse primates. Uplift resulted in increasing aridity and open habitats that drove human evolution.
Abstract
Timing and magnitude of surface uplift are key to understanding the impact of crustal deformation and topographic growth on atmospheric circulation, environmental conditions, and surface processes. Uplift of the East African Plateau is linked to mantle processes, but paleoaltimetry data are too scarce to constrain plateau evolution and subsequent vertical motions associated with rifting. Here, we assess the paleotopographic implications of a beaked whale fossil (Ziphiidae) from the Turkana region of Kenya found 740 km inland from the present-day coastline of the Indian Ocean at an elevation of 620 m. The specimen is ∼17 My old and represents the oldest derived beaked whale known, consistent with molecular estimates of the emergence of modern strap-toothed whales (Mesoplodon). The whale traveled from the Indian Ocean inland along an eastward-directed drainage system controlled by the Cretaceous Anza Graben and was stranded slightly above sea level. Surface uplift from near sea level coincides with paleoclimatic change from a humid environment to highly variable and much drier conditions, which altered biotic communities and drove evolution in east Africa, including that of primates. ||||| A 17-million-year-old beaked whale fossil is helping researchers solve a puzzle about the likely birthplace of humanity in East Africa, a new study finds.
The whale (Ziphiidae) lived when the East African plateau was substantially lower and covered by dense forests, the researchers said. Scientists have long tried to figure out when the uplift occurred, because when it did, the moisture from the Indian Ocean could no longer reach the trees and vegetation, and the area turned into a savannah, research suggests.
Extinct ancestors to modern humans may have lived in trees in East Africa, but after the area turned into grassland, these early humans gradually began walking on two feet, researchers suggest. [Top 10 Mysteries of the First Humans]
"It's more or less the story about the bipedalism," said study researcher Henry Wichura, a postdoctoral candidate in geoscience at University of Potsdam in Germany.
But the timing of the East African plateau uplift has eluded scientists. The whale fossil helps researchers get closer to that date, which likely occurred sometime between 17 million and 13.5 million years ago, according to the new study.
A whale of a tale
The story of the whale skull is one of rediscovery. Researchers originally found the fossil in 1964, but didn't publish a study on it until 1975. Then, they misplaced the skull until 2011.
The skull is the oldest known fossil of a beaked whale, and it confounded researchers at first. Beaked whales are deep divers that live in the ocean, but the fossil was found 460 miles (740 kilometers) inland from the present-day East African coast, and at an elevation of 2,100 feet (640 meters).
Perhaps the 23-foot-long (7 m) whale used to live in the Indian Ocean, but mistakenly strayed into a river that led it into modern-day Kenya, the study researchers said.
Researcher James Mead, as he uncovered the whale fossil in Loperot, Kenya, in 1964. Credit: Image courtesy of James G. Mead
"We came to the idea that it used a large river system, because the whale had been found in lake sediments which are [mixed with] river sediments," Wichura said. "So we can say that it died in a kind of river-lake environment."
But the fossil sat unstudied for nearly 40 years, until researchers rediscovered it at Harvard University. (Interestingly, a curator found the fossil in the former office of renowned paleontologist Stephen Jay Gould. At the time, the university was using Gould's office for temporary storage during a remodel, according to the study.)
Once recovered, the skull helped Wichura and his colleagues date the East African plateau's uplift. They wondered how low the East African plateau was before the region's topography changed, so they searched for other instances of whales getting lost in rivers. For instance, one whale became stranded in the Thames River in 2006, and killer whales have swum into the Columbia River in the Pacific Northwest of the United States.
The scientists took the grade of the steepest river from case reports, and applied it to the prehistoric river used by the whale. So, if the ancient river rose at 2.5 inches a mile (4 centimeters per km) from the coast, the East African plateau was between 79 feet and 121 feet high (24 m and 37 m) at the time the whale lost its way and died. (The difference in height takes into account the different routes the whale may have taken to swim inland from the Indian Ocean.)
Considering that the plateau is now about 2,034 feet (620 m) tall, the northern part of the Eastern African plateau must have been uplifted by about 1,925 feet (590 m) over the past 17 million years, the researchers determined.
Furthermore, Wichura found that at 13.5 million years ago, part of the Eastern African plateau uplift had already begun, putting a bookend on when the uplift started. (He noted that the uplift happened because of mantle plumes, hot material that rises through the Earth's mantle and pushes up against the crust.)
Without the rediscovered skull, it would have been difficult to help date the uplift, he said.
"With the whale, everything started," Wichura told Live Science.
The study reminds both professional and amateur paleontologists to study the location and age of each fossil they find, said Frank Brown, a professorof geology at the University of Utah, who was not involved in the study.
"Even single specimens of organisms tell us a great deal about the history of the Earth, and they sometimes appear in surprising cases," Brown said. "This is one such case."
The study was published today (March 16) in the journal Proceedings of the National Academy of Sciences.
Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science. |||||
What is a shorter version of the above article?
Answer: Researchers have discovered a 22-foot beaked whale fossil about 17 million years old that offers important clues about the climate change forces that played a role in human evolution. The fossil, which had been lost for more than 30 years, suggests that the East African Plateau began rising no earlier than 17 million years ago, according to a study published in the journal Proceedings of the National Academy of Sciences. The geologic upheaval in the area, which is known as the cradle of humankind, led to the gradual transformation of dense, humid forests into sparse grasslands that made walking upright advantageous for evolving human ancestors. The whale bone was found in a thick layer of sediment beneath a lava flow that was 17 million years old, according to the study, and around it, mammal fossils date back to a time when Africa and Eurasia were joined. Researchers used this information to conclude that uplift could not have begun before this time.
Answer: الباحثين لقاو حوت طول 22 قدم عمره 17 مليون عام ويعطي معلومات مهمة على التغيرات المناخية اللي لعبت دور في تطور الإنسان. هالفوسيل كان ضايع أكثر من 30 سنة ويقترح ان الصعود متاع الهضبة الافريقية الشرقية بدا منذ كان 17 مليون عام. حسب دراسة منشورة في مجلة مجريات الأكاديمية الوطنية للعلوم، هالتغير الجيولوجي في منطقة معروفة بأنها مهد البشرية قد تسبب في تحويل الغابات الكثيفة والرطبة لأراض عُشبيّة قليلة الشجر اللي خلات المشي من غير دعم سهل أكثر للإنسان اللي كان يتطور. عظمة الحوت لقتها في طبقة سميكة من الرواسب تحت تدفق الحمم البركانية يرجع تاريخو ل17 مليون عام، وحواليها كانو ماموثات ترجع لنفس الحقبة اللي كانت فيها إفريقيا وأوراسيا متوحدين، ووفق هالمعلومات، الباحثين خرجو بقناعة أن الصعود متاع الهضبة ما نجمش يبدا قبل هالفترة.