Fossils of a carnivorous dinosaur unearthed in Argentina are shedding new light on an intriguing group of predators that apparently were just as happy to slash victims to death with sickle-shaped hand claws as to chomp them into an early grave.
Scientists said on Wednesday the creature, called Murusraptor barrosaensis, lived about 80 million years ago during the Cretaceous Period, measured about 21 feet (6.5 meters) long and was a pursuit hunter more lightly built than some other predatory dinosaurs.
Murusraptor was a member of a group of meat-eaters called megaraptors, meaning "giant thieves," that prowled Patagonia, although fossils of relatives have been discovered in Australia and Japan.
"Most of the different species known from this clade are based on rather fragmentary specimens. The Murusraptor specimen preserved the complete posterior half of the skull, several vertebrae and pelvis bones, unveiling unknown areas of the skeleton of this group," said paleontologist Rodolfo Coria of Argentina's Universidad Nacional de Río Negro.
"The braincase is complete, and is the only known among megaraptors," Coria added. "It brings a unique opportunity to search for characteristics of neurological development in these dinosaurs."
Megaraptors were medium-sized predators compared to some of Argentina's giant Cretaceous meat-eaters, like the roughly 41-foot-long (12.5 meters) Giganotosaurus, and likely hunted in a different way. Giganotosaurus, which lived about 17 million years before Murusraptor, had a massively built skull and large teeth for killing prey, along with puny arms that would have done little good in hunting.
Other scientists last week announced the discovery of fossils of another Argentine carnivorous dinosaur, called Gualicho, a bit larger than Murusraptor that had feeble arms, akin in size to a human child's.
In contrast, megaraptors possessed strong arms that wielded sickle-like claws that could inflict fatal wounds on prey, along with a more lightly built skull and jaws studded with smaller teeth. They also had air-filled, bird-like bones.
But that certainly did not mean an encounter with Murusraptor in prehistoric Patagonia would end well.
"A person might say, 'Oh my god, a megaraptor!' And then he would die," Coria added.
Murusraptor means "thief from the wall," because its fossils were collected from the wall of a creek in Argentina's Neuquen Province.
The research was published in the journal PLOS ONE.
New UNESCO World Heritage sites 2015
New UNESCO World Heritage sites 2015
Where is it? Ephesus can be found in what used to be the estuary of the River Kaystros in Tyurkey.
What is it? The area comprises of a number of Hellenistic and Roman settlements. There are also some remnants of the Temple of Artemis which is one of the 'Seven Wonders of the World'.
Where is it? The mountainous mid-western region of the Republic of Korea.
What is it? These eight archaeological sites date back to 475 to 660 CE and include the royal tombs at Songsan-ri. These site are examples of the later period of the Baekje Kingdom.
Where is it? The site can be found on the eastern bank of the River Jordan, north of the Dead Sea, Jordan
What is it? This is believed to be the place Jesus of Nazareth was baptised by John the Baptist. It is now a Christian place of pilgrimage.
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Where is it? Vineyards of Hautvilliers, Aÿ and Mareuil-sur-Aÿ, Saint-Nicaise Hill in Reims, and the Avenue de Champagne and Fort Chabrol in Epernay.
What is it? This is where the method of producing sparkling wines has been developed since the 17th century.
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Where is it? Near the Uruguay River, west of the town of Fray Bentos.
What is it? The industrial area was built after the development of a factory in 1859. The purpose of the factory was to process the meat that was produced on the prairie lands nearby.
Where is it? Between the states of Mexico and Hidalgo, on the Central Mexican Plateau.
What is it? The 45km long aqueduct has a total of 126 arches and the site include the highest single-level arcade ever built in an aqueduct.
Where is it? The north-east of Mongolia in the central part of the Khentii mountain chain.
What is it? Burkhan Khaldun is associated with the worship of sacred mountains, rivers and ovoo-s (shamanic rock cairns).This is also thought to be where Genghis Khan was born and buried.
Where is it? The Necropolis can be found south east of the city of Haifa.
What is it? This was the primary Jewish burial site outside Jerusalem after the failure of the Jewish revolt against Roman rule.The catacombs are also home to artworks and inscriptions in Greek, Aramaic and Hebrew.
Where is it? On the northern coast of Sicily.
What is it? This series of nine civil and religious structures date back to the Norman kingdom of Sicily (1130 - 1194). It is comprised of two palaces, three churches, a cathedral, a bridge, as well as the cathedrals of Cefalú and Monreale.
Where is it? Rjukan is in Vestfjorddalen, between Møsvatn and Tinnsjå.
What is it? The complex was started by Norsk-Hydro to produce artificial fertiliser from nitrogen in the air. The site is made up of power plants, factories, transport systems and the company towns of Rjukan and Notodden.
Where is it? There are two sites found in the desert region - Jabel Umm Sinman at Jubbah and the Jabal al-Manjor and Raat at Shuwaymis.
What is it? Arab ancestors have left their mark on the region showing their passage through the area with a number of petroglyphs and inscriptions on the rock face.
Where is it? There are five mission complexes found along the San Antonio River basin in southern Texas, as well as a ranch further south.
What is it? They were built by Franciscan missionaries in the 18th century and illustrate the Spanish efforts to colonise.
Where is it? In the heart of Singapore.
What is it? The gardens demonstrate the evolution of the British tropical and colonial gardens. The landscape includes a variety of historic features and buildings.
Where is it? In the port city of Hamburg.
What is it? These two densely populated areas exemplify the effects of the rapid growth in international trade during the later 19th century to early 20th century.
Where is it? In the south-west of Iran, in the lower Zagros Mountains.
What is it? The property includes a number of archaeological mounds and the excavated archaeological monuments contain several layers of urban settlements that represent the anicent Elamite, Persian and Parthian cultures.
Where is it? On the slopes of the Côte de Nuits and the Côte de Beaune south of the city of Dijon.
What is it? The specific natural conditions sets this area apart from other vineyards. The cultural landscape consists of the vineyards and the historic centre of Dijon which is home to the 'climatssystem'. The area is an outstanding example of grape cultivation and wine production.
Where is it? About 30 km northeast of Copenhagen.
What is it? The landscape includes the two hunting forests of Store Dyrehave and Gribskov, as well as the hunting park of Jægersborg Hegn. This is where Danish kings would have exercised 'par force' hunting from the Middle Ages to end of the 16th century.
Where is it? Vietnam
What is it? The national park features plenty of geological diversity and the park is formed of limestone plateau and tropical forests. There are also a large number of underground caves and rives running throughout the park.
Where is it? South Jutland, Denmark.
What is it? The site is a planned settlement of the Moravian Church which is a Lutheran free congregation. The town was built to represnet the protestant urban ideal which is constructed around a central church square.
Where is it? At the end of a valley at the southern extremity of Iran’s central mountains.
What is it? The villagers are semi-nomadic agro-pastoralists who raise their animals on mountain pastures and live in temporary settlements. In the winter they live lower down the valley in cave dwellings carved from soft rock.
Where is it? Mountainous areas of south-west China.
What is it? The property includes the remains of several tribal domains who were made 'Tusi' by the government. The sites of Laosicheng, Tangya and Hailongtun Fortress are derived from the Chinese civilization of the Yuan and Ming periods.
Where is it? The south-western extremity of South Africa.
What is it? This is one of the world's greatest centres of biodiversity and the property included national parks, nature reserves and state forests. A Mediterranean climate and periodic fires are unique to the Cape Floral Region.
Where is it? Northern Spain.
What is it? This is a network of four Christian pilgrimage routes which includes buildings of historical importance including cathedrals, hospitals, bridges and more. The extension of these routes included some of the earliest pilgrimage routes to Santiago de Compostela.