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News Article | May 3, 2017
Site: news.yahoo.com

A 145-million-year-old dinosaur about the size of a wild turkey sported a plume of tail feathers that were surprisingly modern-looking and aerodynamic in shape, a new study finds. Though flight ready, the beast's tail feathers may or may not have been used for flying, said the researchers who found the exceptional specimen, a roughly 3.6-foot-long (1.1 meters) dinosaur, in 2015 in China's Liaoning Province, an area known for its incredibly well-preserved fossils of dinosaurs with feathers. The scientists named the find Jianianhualong tengi, after Jianianhua, the Chinese company that supported the study, and "long," the Mandarin word for "dragon," the researchers said. The species name honors Fangfang Teng, the director of the Xinghai Paleontological Museum of Dalian in China, who helped the paleontologists access the specimen. [Images: These Downy Dinosaurs Sported Feathers] J. tengi, which weighed just over 5 lbs. (2.4 kilograms), was a troodontid, a bird-like theropod. Though most theropods, such as Velociraptor and Tyrannosaurus rex, were carnivorous, J. tengi was likely an omnivore, based on its tooth anatomy and the diet of its closest relatives, said study co-lead researcher Michael Pittman, an assistant professor of vertebrate paleontology at the University of Hong Kong. Unlike the symmetrical feathers seen on most dinosaurs from the Cretaceous period, J. tengi's feathers were asymmetrical, with the vanes on one side of the central shaft longer than those on the other side — a feature that is crucial for flight, the researchers said. "Bird feathers need to be asymmetrical in order to form an airfoil," said Steve Brusatte, a vertebrate paleontologist at the University of Edinburgh, who was not involved with the study. "It has to do with the physics of wing shape, the same way that airplane wings have to be designed a certain way." However, asymmetrical feathers "are also found in species that do not fly," making it unclear whether the Cretaceous-age dinosaur could take flight, Pittman said. The asymmetrical feathers on J. tengi's tail are the first record of aerodynamically associated feathers in the bird-like troodontid dinosaurs, Pittman said. The Velociraptor relative Microraptor (a dromaeosaur) also had asymmetrical feathers, Pittman said. "This reveals that the closest common ancestor of birds (shared with troodontids and the bird-like dromaeosaur dinosaurs, raptors), possessed asymmetrical feathers," Pittman told Live Science in an email. The finding will likely help paleontologists decipher the timing of the evolution of asymmetrical feathers, both Pittman and Brusatte said. "Strangely enough, the asymmetrical feathers are on the tail," Brusatte told Live Science in an email. "Does this mean that Jianianhualong was using its tail to fly? It's hard to be sure." [Photos: Velociraptor Cousin Had Short Arms and Feathery Plumage] J. tengi's arm and leg feathers aren't preserved well enough to show their symmetry, "so we don't know what the feather condition of the entire animal would have been like," Brusatte said. "It is possible that Jianianhualong had asymmetrical tail feathers, but symmetrical (and thus non-flight-worthy) arm and leg feathers like most other nonbird dinosaurs. We just don't know." Perhaps feather asymmetry evolved first for display purposes before the features were used for flight, Brusatte said. The investigation into the history of flight is a hot topic, as a growing number of researchers try to determine which dinosaurs could fly. For instance, research presented at the 2016 Society of Vertebrate Paleontology meeting in Salt Lake City showed that several dinosaurs, such as Microraptor, and early birds, including Archaeopteryx, could likely fly for short distances, Live Science previously reported. The new study was published online today (May 2) in the journal Nature Communications.


In November 2010, ranch manager David Bradt was hunting elk in northeast Montana when he found what first appeared to be a petrified wood sticking out of a rock. He eventually discovered that it was a vertebrae of fossilized bones. That fossil helped researchers discover a new species of prehistoric marine reptile that swam in the inland sea flowing east of the Rocky Mountains about 70 million years ago. Scientists named the new species Nakonanectes bradti, which stands for Nakona, or Assiniboine, the people of northeastern Montana, and Bradt who first discovered the specimen while hunting elk. The marine animal belonged to a group of long-necked plesiosaurs called elasmosaur, which are characterized by small heads and paddle-like limbs and can grow up to 30 feet long. The carnivorous reptiles are a type of prehistoric marine creature that are known for their long neck that stretches 18 feet long. The fossil that Bradt discovered in the Charles M. Russell National Wildlife Refuge called MOR 3072 is distinct in that it belonged to a creature that has a shorter neck measuring just about 7.5 feet. Paleontologist Patrick Druckenmiller, from the University of Alaska Museum of the North, who coauthored the study describing the fossilized remains of the new species, said that this group of prehistoric animals is known for their long necks, which contain as many as 76 vertebrae. "What absolutely shocked us when we dug it out — it only had somewhere around 40 vertebrae," Druckenmiller said. The creature lived in the same area and at the same time as its larger relatives, which contradicts the idea that elasmosaurs did not evolve over a period spanning millions of years to have their longer necks. Fossils of these creatures have been found across the world, but the one that was discovered in Montana was nearly complete and was well-preserved. When Bradt found the fossils, he initially thought these belonged to a triceratops. He was surprised to learn it was a sea creature because he did not know there used to be an ocean there. Bradt took photos and reported his find to the Museum of the Rockies in Bozeman and the U.S. Fish and Wildlife Service. It took three days before the fossil was excavated. Millions of years ago, dinosaurs such as Tyrannosaurus rex, Thescelosaurus, Triceratops, and Pachycephalosaurus inhabited the land and sea in the area. Researchers said that the inland sea was also teeming with marine creatures, but relatively a few of these fossils have so far been excavated. "MOR 3072 is one of the smallest adult elasmosaurids ever recovered (5.1-5.6 m) and exhibits a reduced neck length compared with other North American elasmosaurids, resulting from a reduction in both centrum length and number of cervical vertebrae (39-42 were originally present)," researchers wrote in their study, which was published in the Journal of Vertebrate Paleontology on Thursday, April 13. "These features are convergent with the Southern Hemisphere clade of short-necked Maastrichtian elasmosaurids, Aristonectinae, and demonstrate multiple origins of short-necked body proportions from longer-necked ancestors within Elasmosauridae." © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | May 2, 2017
Site: www.eurekalert.org

Genetic studies of cichlid fishes suggest that interspecies hybrids played a prominent role in their evolution. Analysis of a unique fossil cichlid from the Upper Miocene of East Africa now provides further support for this idea. The cichlids constitute one of the most diverse families of freshwater fishes in tropical habitats. Its members have adapted to the demands of a wide range of ecological niches, and many have developed highly specialized feeding habits. Contemporary representatives of the family therefore provide an ideal model system for evolutionary biologists who seek to understand the mechanisms that underlie the process of species diversification. Unfortunately, fossil specimens that could help to trace earlier phases of cichlid evolution are quite rare, and most are poorly preserved and/or fragmentary. Now scientists around Ludwig-Maximilians-Universitaet (LMU) in Munich paleontologist Professor Bettina Reichenbacher have described a new fossil cichlid discovered in Upper Miocene strata in East Africa, which provides new insights into the evolutionary history of the group. Moreover, the results are consistent with molecular genetic data relating to the ongoing diversification of the family in the Great Lakes region of East Africa, which have indicated that hybridization between members of related species or even genera has played a major role in cichlid speciation. The work also sheds light on the environmental conditions that prevailed in the Rift Valley of East Africa in the Upper Miocene period, 9-10 million years ago. The new findings appear in the Journal of Vertebrate Paleontology. The authors assign the fossil to a newly defined genus and species (Tugenchromis pickfordi). In light of the scarcity of well-preserved cichlid fossils, the phylogenetic placement of the new specimen is dependent on comparisons with modern members of the family -- and given the enormous diversity of the latter, this is by no means an easy task. However, in cooperation with Dr. Ulrich Schliewen (Zoological State Collections, Munich), Reichenbacher and her team have assembled a unique database on the morphology of present-day cichlids, in which all the lineages found in Lake Tanganyika are represented. This dataset is based on the painstaking analysis of X-ray photographs of the skeletons of 763 individuals belonging to 227 modern cichlid species. "This unique resource has made it possible for the first time to place a new fossil species securely within the phylogeny of African cichlids. Indeed, our analysis shows it to be a member of the most ancient cichlid lineage that contributed to the so-called East African Radiation, a spectacular burst of diversification that has given rise to a huge variety of species," Reichenbacher explains. The new fossil displays a striking "mosaic-like" set of characters, combining traits that are typical for three distinct cichlid groups found in Lake Tanganyika today. "This combination of characters is particularly interesting, because molecular geneticists have shown that many of the cichlid species in Lake Tanganyika possess 'mosaic' genomes -- made up of genetic material derived from non-related species. The mosaic of characters displayed by the fossil specimen is a reflection of the morphological consequences of such interspecies hybridization," says Dr. Melanie Altner, first author of the study. The basin now occupied by Lake Tanganyika came into being at least 5.5 million years ago, and it has been assumed that the species radiation that gave rise to the striking diversity of cichlids in the lake was triggered by its formation. However, new models based on molecular genetic analyses of these cichlid species suggest that an radiation -- driven in part by interspecies hybridization - was already underway in the rivers and lakes that drained into the Proto-Lake Tanganyika. "In fish, it is not uncommon for such hybrids, which display characters derived from both parental species, to be fertile and capable of producing fertile progeny," says Schliewen. During the Miocene and Pliocene periods, the climate of East Africa became more arid, and many feeder streams dried up. As a result, many cichlid species that had originated in riverine systems were isolated in Lake Tanganyika basin itself, which thus became a 'melting pot' for subsequent episodes of speciation to which these immigrant species contributed. "Our fossil supports the hypothesis that hybridizations played a more prominent role in cichlid speciation than was once thought - and that diversification of the cichlids now endemic to the lake did not begin in the lake itself," Reichenbacher says. The new fossil also elucidates aspects of the environment in which Lake Tanganyika formed. It was discovered by Reichenbacher and her coworkers in Kenya's Tugen Hills, in the eastern arm of the East African Rift Valley, but Lake Tanganyika -- in which its closest relatives now live -- is located in the Valley's western branch. The fossil therefore provides further evidence for a previously postulated hydrological connection between the eastern and western arms of the Rift Valley, which was subsequently severed as rifting progressed.


News Article | March 30, 2017
Site: www.techtimes.com

Paleontologists have revealed the discovery of the world's biggest dinosaur footprint as well as the world's most diverse collection of dinosaur tracks in Australia. The gigantic footprint belonged to a sauropod, an herbivorous dinosaur marked by its long neck, which likely measured 17 feet and 9 inches high at the hips. The track, which measures nearly 5 feet and 9 inches, is bigger than the previous record holder, which measured just nearly 3 feet and 9 inches. The footprint is just one of a series of finds that scientists discovered in Australia's "Jurassic Park." Researchers also found 21 different dinosaur tracks and some rocks dating back from as early as 140 million years ago. The footprints, which were between 140 million and 127 million years old, vary in size. They range from small, measuring about 8 inches, to very large, measuring over 5 feet in length. The footprints are considered as trace fossils, left behind by animals but are not parts of the animals themselves. The trace fossils revealed the diversity of dinosaurs that lived around the region during the Cretaceous period, the geologic period marked by relatively warm climate and an abundance of now-extinct marine reptiles, ammonites, and dinosaurs. The Cretaceous period ended with the Cretaceous-Paleogene extinction event, in which some three-quarters of animals and plants on the planet died out. Analyses showed five different track types of predatory dinosaurs, six track types of sauropods, four track types of herbivorous ornithopods, and six track types of armored dinosaurs. Paleontologist Steve Salisbury from the University of Queensland said that the findings show that Broome, a town on Australia's western coast, was once a dinosaur hot spot. He said that the diversity of the tracks was unparalleled on a global level and made the area the "Cretaceous equivalent of the Serengeti." Serengeti in Africa currently hosts the largest terrestrial mammal migration in the world. The region hosts about 70 large mammal and 500 bird species. "The overall diversity of the dinosaurian ichnofauna of the Broome Sandstone in the Yanijarri-Lurujarri section of the Dampier Peninsula is unparalleled in Australia, and even globally," the researchers wrote in their study, which was published on March 24 in the Journal of Vertebrate Paleontology. "[T]his ichnofauna provides our only detailed glimpse of Australia's dinosaurian fauna during the first half of the Early Cretaceous," they added. The tracks are not just fascinating. Scientists are also excited about the find since the dinosaur footprints can help them learn more about the anatomy, diversity, and evolution of the dinosaurs. Analyses of dinosaur bones allow scientists to study the iconic prehistoric animals, but footprints also offer an array of information about these large creatures. "What stands out are [the footprints'] immense physical size and the great variety of dinosaur tracks found there," said paleontologist Steve Brusatte from the University of Edinburgh. "Obviously, this part of Australia must have been a dinosaur stomping ground during the Early Cretaceous." © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | May 18, 2017
Site: news.yahoo.com

According to a new study, the famed Tyrannosaurus rex had quite the bite. With these powerful jaws, a T. rex could demolish bones with forces equaling the weight of three small cars. The predator-scavanger could bite down with nearly 8,000 pounds of force, more than twice the bite force of the largest living crocodiles, the modern bite force kings. Eating bones, known as extreme osteophagy in scientific communities, is not uncommon today, but it usually happens among carnivorous mammals like wolves or hyenas. Reptiles generally do not have the tooth structure to break down bone. "It was this bone-crunching acumen that helped T. rex to more fully exploit the carcasses of large horned-dinosaurs and duck-billed hadrosaurids whose bones, rich in mineral salts and marrow, were unavailable to smaller, less equipped carnivorous dinosaurs," says Paul Gignac, assistant professor of Anatomy and Vertebrate Paleontology at Oklahoma State. This joint study study between Florida State and Oklahoma State also shows the power of each individual tooth. A tyrannosaurus tooth could generate 431,000 pounds per square inch. This allowed the dinosaur to bite down repetitively on a bone like a mammal would. The splintering bones would likely sometimes explode out of the the giant reptile's mouth. After studying birds and crocodilians, the scientists realized that it wasn't just strong jaw muscles that allowed the might beast to destroy bone. It was also how that force was transferred to the teeth itself, a metric they called tooth pressure. "Having high bite force doesn't necessarily mean an animal can puncture hide or pulverize bone, tooth pressure is the biomechanically more relevant parameter," says Florida State Professor of Biological Science Gregory Erickson. "It is like assuming a 600 horsepower engine guarantees speed. In a Ferrari, sure, but not for a dump truck." The T. Rex's celebrity status, which began when the dinosaur first was discovered in 1905, affords it a unique place among paleontological studies. Many, like the late palentologist Robert Bakker, attribute it to that spectacular name, Tyrannosaurus, which just rolls off the tongue. This close reading of its bone-destroying abilities shows that it had the bite to live up to the hype. You Might Also Like


News Article | May 17, 2017
Site: www.rdmag.com

The giant Tyrannosaurus rex pulverized bones by biting down with forces equaling the weight of three small cars while simultaneously generating world record tooth pressures, according to a new study by a Florida State University-Oklahoma State University research team. In a study published today in Scientific Reports, Florida State University Professor of Biological Science Gregory Erickson and Paul Gignac, assistant professor of Anatomy and Vertebrate Paleontology at Oklahoma State University Center for Health Sciences, explain how T. rex could pulverize bones -- a capacity known as extreme osteophagy that is typically seen in living carnivorous mammals such as wolves and hyenas, but not reptiles whose teeth do not allow for chewing up bones. Erickson and Gignac found that this prehistoric reptile could chow down with nearly 8,000 pounds of force, which is more than two times greater than the bite force of the largest living crocodiles -- today's bite force champions. At the same time, their long, conical teeth generated an astounding 431,000 pounds per square inch of bone-failing tooth pressures. This allowed T. rex to drive open cracks in bone during repetitive, mammal-like biting and produce high-pressure fracture arcades, leading to a catastrophic explosion of some bones. "It was this bone-crunching acumen that helped T. rex to more fully exploit the carcasses of large horned-dinosaurs and duck-billed hadrosaurids whose bones, rich in mineral salts and marrow, were unavailable to smaller, less equipped carnivorous dinosaurs," Gignac said. The researchers built on their extensive experience testing and modeling how the musculature of living crocodilians, which are close relatives of dinosaurs, contribute to bite forces. They then compared the results with birds, which are modern-day dinosaurs, and generated a model for T. rex. From their work on crocodilians, they realized that high bite forces were only part of the story. To understand how the giant dinosaur consumed bone, Erickson and Gignac also needed to understand how those forces were transmitted through the teeth, a measurement they call tooth pressure. "Having high bite force doesn't necessarily mean an animal can puncture hide or pulverize bone, tooth pressure is the biomechanically more relevant parameter," Erickson said. "It is like assuming a 600 horsepower engine guarantees speed. In a Ferrari, sure, but not for a dump truck." In current day, well-known bone crunchers like spotted hyenas and gray wolves have occluding teeth that are used to finely fragment long bones for access to the marrow inside -- a hallmark feature of mammalian osteophagy. Tyrannosaurus rex appears to be unique among reptiles for achieving this mammal-like ability but without specialized, occluding dentition. The new study is one of several by the authors and their colleagues that now show how sophisticated feeding abilities, most like those of modern mammals and their immediate ancestors, actually first appeared in reptiles during the Age of the Dinosaurs.


TALLAHASSEE, Fla. -- The giant Tyrannosaurus rex pulverized bones by biting down with forces equaling the weight of three small cars while simultaneously generating world record tooth pressures, according to a new study by a Florida State University-Oklahoma State University research team. In a study published today in Scientific Reports, Florida State University Professor of Biological Science Gregory Erickson and Paul Gignac, assistant professor of Anatomy and Vertebrate Paleontology at Oklahoma State University Center for Health Sciences, explain how T. rex could pulverize bones -- a capacity known as extreme osteophagy that is typically seen in living carnivorous mammals such as wolves and hyenas, but not reptiles whose teeth do not allow for chewing up bones. Erickson and Gignac found that this prehistoric reptile could chow down with nearly 8,000 pounds of force, which is more than two times greater than the bite force of the largest living crocodiles -- today's bite force champions. At the same time, their long, conical teeth generated an astounding 431,000 pounds per square inch of bone-failing tooth pressures. This allowed T. rex to drive open cracks in bone during repetitive, mammal-like biting and produce high-pressure fracture arcades, leading to a catastrophic explosion of some bones. "It was this bone-crunching acumen that helped T. rex to more fully exploit the carcasses of large horned-dinosaurs and duck-billed hadrosaurids whose bones, rich in mineral salts and marrow, were unavailable to smaller, less equipped carnivorous dinosaurs," Gignac said. The researchers built on their extensive experience testing and modeling how the musculature of living crocodilians, which are close relatives of dinosaurs, contribute to bite forces. They then compared the results with birds, which are modern-day dinosaurs, and generated a model for T. rex. From their work on crocodilians, they realized that high bite forces were only part of the story. To understand how the giant dinosaur consumed bone, Erickson and Gignac also needed to understand how those forces were transmitted through the teeth, a measurement they call tooth pressure. "Having high bite force doesn't necessarily mean an animal can puncture hide or pulverize bone, tooth pressure is the biomechanically more relevant parameter," Erickson said. "It is like assuming a 600 horsepower engine guarantees speed. In a Ferrari, sure, but not for a dump truck." In current day, well-known bone crunchers like spotted hyenas and gray wolves have occluding teeth that are used to finely fragment long bones for access to the marrow inside -- a hallmark feature of mammalian osteophagy. Tyrannosaurus rex appears to be unique among reptiles for achieving this mammal-like ability but without specialized, occluding dentition. The new study is one of several by the authors and their colleagues that now show how sophisticated feeding abilities, most like those of modern mammals and their immediate ancestors, actually first appeared in reptiles during the Age of the Dinosaurs. This work was supported by grants from the National Science Foundation and the National Geographic Society.


News Article | May 17, 2017
Site: www.chromatographytechniques.com

The giant Tyrannosaurus rex pulverized bones by biting down with forces equaling the weight of three small cars while simultaneously generating world record tooth pressures, according to a new study by a Florida State University-Oklahoma State University research team. In a study published today in Scientific Reports, Florida State University Professor of Biological Science Gregory Erickson and Paul Gignac, assistant professor of Anatomy and Vertebrate Paleontology at Oklahoma State University Center for Health Sciences, explain how T. rex could pulverize bones — a capacity known as extreme osteophagy that is typically seen in living carnivorous mammals such as wolves and hyenas, but not reptiles whose teeth do not allow for chewing up bones. Erickson and Gignac found that this prehistoric reptile could chow down with nearly 8,000 pounds of force, which is more than two times greater than the bite force of the largest living crocodiles — today’s bite force champions. At the same time, their long, conical teeth generated an astounding 431,000 pounds per square inch of bone-failing tooth pressures. This allowed T. rex to drive open cracks in bone during repetitive, mammal-like biting and produce high-pressure fracture arcades, leading to a catastrophic explosion of some bones. “It was this bone-crunching acumen that helped T. rex to more fully exploit the carcasses of large horned-dinosaurs and duck-billed hadrosaurids whose bones, rich in mineral salts and marrow, were unavailable to smaller, less equipped carnivorous dinosaurs,” Gignac said. The researchers built on their extensive experience testing and modeling how the musculature of living crocodilians, which are close relatives of dinosaurs, contribute to bite forces. They then compared the results with birds, which are modern-day dinosaurs, and generated a model for T. rex. From their work on crocodilians, they realized that high bite forces were only part of the story. To understand how the giant dinosaur consumed bone, Erickson and Gignac also needed to understand how those forces were transmitted through the teeth, a measurement they call tooth pressure. “Having high bite force doesn’t necessarily mean an animal can puncture hide or pulverize bone, tooth pressure is the biomechanically more relevant parameter,” Erickson said. “It is like assuming a 600 horsepower engine guarantees speed. In a Ferrari, sure, but not for a dump truck.” In current day, well-known bone crunchers like spotted hyenas and gray wolves have occluding teeth that are used to finely fragment long bones for access to the marrow inside — a hallmark feature of mammalian osteophagy. Tyrannosaurus rex appears to be unique among reptiles for achieving this mammal-like ability but without specialized, occluding dentition. The new study is one of several by the authors and their colleagues that now show how sophisticated feeding abilities, most like those of modern mammals and their immediate ancestors, actually first appeared in reptiles during the Age of the Dinosaurs.


The giant Tyrannosaurus rex pulverized bones by biting down with forces equaling the weight of three small cars while simultaneously generating world record tooth pressures, according to a new study by a Florida State University-Oklahoma State University research team. In a study published today in Scientific Reports, Florida State University Professor of Biological Science Gregory Erickson and Paul Gignac, assistant professor of Anatomy and Vertebrate Paleontology at Oklahoma State University Center for Health Sciences, explain how T. rex could pulverize bones -- a capacity known as extreme osteophagy that is typically seen in living carnivorous mammals such as wolves and hyenas, but not reptiles whose teeth do not allow for chewing up bones. Erickson and Gignac found that this prehistoric reptile could chow down with nearly 8,000 pounds of force, which is more than two times greater than the bite force of the largest living crocodiles -- today's bite force champions. At the same time, their long, conical teeth generated an astounding 431,000 pounds per square inch of bone-failing tooth pressures. This allowed T. rex to drive open cracks in bone during repetitive, mammal-like biting and produce high-pressure fracture arcades, leading to a catastrophic explosion of some bones. "It was this bone-crunching acumen that helped T. rex to more fully exploit the carcasses of large horned-dinosaurs and duck-billed hadrosaurids whose bones, rich in mineral salts and marrow, were unavailable to smaller, less equipped carnivorous dinosaurs," Gignac said. The researchers built on their extensive experience testing and modeling how the musculature of living crocodilians, which are close relatives of dinosaurs, contribute to bite forces. They then compared the results with birds, which are modern-day dinosaurs, and generated a model for T. rex. From their work on crocodilians, they realized that high bite forces were only part of the story. To understand how the giant dinosaur consumed bone, Erickson and Gignac also needed to understand how those forces were transmitted through the teeth, a measurement they call tooth pressure. "Having high bite force doesn't necessarily mean an animal can puncture hide or pulverize bone, tooth pressure is the biomechanically more relevant parameter," Erickson said. "It is like assuming a 600 horsepower engine guarantees speed. In a Ferrari, sure, but not for a dump truck." In current day, well-known bone crunchers like spotted hyenas and gray wolves have occluding teeth that are used to finely fragment long bones for access to the marrow inside -- a hallmark feature of mammalian osteophagy. Tyrannosaurus rex appears to be unique among reptiles for achieving this mammal-like ability but without specialized, occluding dentition. The new study is one of several by the authors and their colleagues that now show how sophisticated feeding abilities, most like those of modern mammals and their immediate ancestors, actually first appeared in reptiles during the Age of the Dinosaurs.


News Article | March 1, 2017
Site: www.sciencemag.org

Since their discovery in 2010, the ex­tinct ice age humans called Deniso­vans have been known only from bits of DNA, taken from a sliver of bone in the Denisova Cave in Siberia, Russia. Now, two partial skulls from eastern China are emerging as prime candidates for showing what these shadowy people may have looked like. In a paper published this week in , a Chinese-U.S. team presents 105,000- to 125,000-year-old fossils they call “archaic Homo.” They note that the bones could be a new type of human or an eastern variant of Neandertals. But although the team avoids the word, “everyone else would wonder whether these might be Denisovans,” which are close cousins to Neandertals, says paleo­anthropologist Chris Stringer of the Natural History Museum in London. The new skulls “definitely” fit what you’d expect from a Denisovan, adds paleoanthropologist María Martinón-Torres of the University College London—“something with an Asian flavor but closely related to Neandertals.” But because the investigators have not extracted DNA from the skulls, “the possibility remains a speculation.” Back in December 2007, archaeologist Zhan-Yang Li of the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing was wrapping up his field sea­son in the town of Lingjing, near the city of Xuchang in the Henan province in China (about 4000 kilometers from the Denisova Cave), when he spotted some beautiful quartz stone tools eroding out of the sedi­ments. He extended the field season for two more days to extract them. On the very last morning, his team discovered a yellow piece of rounded skull cap protruding from the muddy floor of the pit, in the same layer where he had found the tools. The team went back for another six sea­sons and managed to find 45 more fossils that fit together into two partial crania. The skulls lack faces and jaws. But they include enough undistorted pieces for the team to note a close resemblance to Ne­andertals. One cranium has a huge brain volume of 1800 cubic centimeters—on the upper end for both Neandertals and moderns—plus a Neandertal-like hollow in a bone on the back of its skull. Both cra­nia have prominent brow ridges and inner ear bones that resemble those of Neander­tals but are distinct from our own species, Homo sapiens. However, the crania also differ from the western Neandertals of Europe and the Middle East. They have thinner brow ridges and less robust skull bones, similar to early modern humans and some other Asian fossils. “They are not Neandertals in the full sense,” says co-author Erik Trinkaus, a paleoanthropologist at Washington Univer­sity in St. Louis in Missouri. Nor are the new fossils late-occurring representatives of other archaic humans such as H. erectus or H. heidelbergensis, two species that were ancestral to Nean­dertals and modern humans. The skulls are too lightly built and their brains are too big, according to the paper. The skulls do share traits with some other fossils in east Asia dating from 600,000 to 100,000 years ago that also defy easy classification, says paleoanthropologist Rick Potts of the Smithsonian Na­tional Museum of Natural History in Washington, D.C. Those features include a broad cranial base where the skull sits atop the spinal column and a low, flat plateau along the top of the skull. The Lingjing crania also resemble another archaic early human skull that dates to 100,000 years ago from Xujiayao in China’s Nihewan Ba­sin 850 kilometers to the north, according to co-author Xiu-Jie Wu, a paleoanthropologist at IVPP. Wu thinks those fossils and the new skulls “are a kind of unknown or new ar­chaic human that survived on in East Asia to 100,000 years ago.” Based on similari­ties to some other Asian fossils, she and her colleagues think the new crania repre­sent regional members of a population in eastern Asia who passed local traits down through the generations in what the re­searchers call regional continuity. At the same time, resemblances to both Nean­dertals and modern humans suggest that these archaic Asians mixed at least at low levels with other archaic people. To other experts, the Denisovans fit that description: They are roughly dated to ap­proximately 100,000 to 50,000 years ago, and their DNA shows that after hundreds of thousands of years of isolation, they mixed both with Neandertals and early modern humans. “This is exactly what the DNA tells us when one tries to make sense of the Denisova discoveries,” says paleoanthropologist Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. “These Chinese fossils are in the right place at the right time, with the right features.” But Wu and Trinkaus say they can’t put fossils in a group defined only by DNA. “I have no idea what a Denisovan is,” Trinkaus says. “Neither does anybody else. It’s a DNA sequence.” The only way to truly identify a Den­isovan is with DNA. IVPP paleogeneticist Qiaomei Fu says she tried to extract DNA from three pieces of the Xuchang fossils but without success. Regardless of the new skulls’ precise identity, “China is rewriting the story of human evolution,” Martinón-Torres says. “I find this tremendously exciting!”

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