(Inside Science) -- The largest, heaviest animals to ever walk on Earth were the long-necked, long-tailed vegetarian dinosaurs known as the sauropods, and the most emblematic sauropods were likely the diplodocoids, which included some of the longest animals of all time, such as the Brontosaurus. Now scientists have discovered the earliest known diplodocoid, and the first from East Asia. They dubbed the new species "the amazing dragon of Lingwu," after the region in China where it was found. This discovery suggests this group of dinosaurs, and possibly others, may have evolved more rapidly than previously thought.
Dinosaurs first appeared roughly 230 million years ago, back when all of today's continents were bound together in the supercontinent Pangaea. Although scientists have found sauropod fossils across the globe, the absence of diplodocoids from East Asia until now suggested these reptiles failed to reach that area before Pangaea fragmented and East Asia became isolated.
Now scientists have discovered a new species of diplodocoid from the Lingwu region in northwest China that dates from about 174 million years ago. "We kind of didn't believe these fossils when we first saw them -- we didn't expect them there," said study co-lead author Xing Xu, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing.
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In 2004, a farmer in Lingwu discovered these fossils in the desert while tending goats, Xu said. In four subsequent excavations, researchers dug up the partial remains of seven to 10 members of this new species, including most parts of the skeleton of one specimen. "For me, the most difficult aspects were clambering down into the quarries and wandering around the bones without treading on them," said study co-lead author Paul Upchurch, a vertebrate paleontologist at University College London in England.
The scientists named the species Lingwulong shenqi. Lingwulong means "dragon of Lingwu," while the researchers said shenqi comes from a Chinese term meaning "amazing," reflecting the unexpected nature of this dinosaur.
The researchers estimated that Lingwulong was 12 to 14 meters long and noted that two of its close relatives of roughly the same size likely weighed 10 to 11 metric tons. In addition, the dinosaur may have possessed "a whiplash tail -- a series of thin elongated tail vertebrae at the end of the tail that formed a weapon," Upchurch said. (Previous research suggested that certain sauropods could crack their tails at supersonic speeds like bullwhips.)
Back when Lingwulong was alive, the site was probably warm and wet. "Many of the rocks in the area, including those that preserved fossils, show evidence of the presence of lakes, river systems and swamps," Upchurch said. "The lakes and rivers had numerous different types of invertebrates, including various mollusks and microscopic animals and plants. There are quite a few plant fossils known from this time and region, suggesting a fairly lush vegetation comprising conifers, ferns and other plants, but there were no flowering plants because these were yet to evolve."
The discovery of Lingwulong may overturn the long-held belief that East Asia had different dinosaurs because it was cut off by seaways from the rest of the world for major periods during the Jurassic, Upchurch said. "One of the supporting lines of evidence for this isolation was that the diplodocoids were present in many other places around the world during the late Jurassic, but had never been found in East Asia," he said.
"The discovery of Lingwulong means that there is clearly something wrong with this isolation hypothesis," Upchurch added. They suggest that diplodocoids lived in East Asia after all, but that scientists have only just now discovered them because of the very patchy nature of the fossil record.
The early nature of these fossils also suggest that sauropods may have diversified rapidly in the Early Jurassic, with major groups of sauropods originating more than 15 million years earlier than previously thought, said Kristina Curry Rogers, a vertebrate paleontologist at Macalester College in St. Paul, Minnesota, who did not take part in this research. This in turn suggests that scientists might also re-examine the histories of other groups, including pterosaurs, lizards, mammals, meat-eating theropod dinosaurs, and plant-eating ornithischian dinosaurs, she added. "The Early Jurassic may prove to be a hotbed for evolution and diversification in terrestrial environments," she noted.
The scientists detailed their findings online July 24 in the journal Nature Communications.