Chinese paleontologists have identified at least two new species of massive dinosaurs that once roamed the Xinjiang Uyghur Autonomous Region in northwestern China some 130 million years ago.

The newly-revealed bones belonged to a group of long-necked plant-eating dinosaurs that include titanosaurs, according to the study published Thursday in the peer-reviewed journal Scientific Reports. Titanosaurs were among the largest dinosaurs known to have ever existed on Earth, with notable species like the Patagotitan mayorum estimated to be as long as 37 meters long.

The two dinosaurs revealed in Thursday’s study are the first of their kind to be found in the Turpan-Hami Basin in Xinjiang. Their discovery adds to the evidence that the region hosted rich biodiversity during the Cretaceous period that ended some 66 million years ago, according to researchers.

Wang Xiaolin, the study’s lead author, told Sixth Tone that they unearthed the fossils between 2008 and 2016 in the vast areas of the Gobi Desert in the Turpan-Hami Basin. They were then digging fossils of pterosaurs, an extinct winged reptile that coexisted with dinosaurs millions of years ago.

“There are just so many pterosaur fossils in the region, even their eggs and embryos,” said Wang, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences. “In some areas, you can find at least one specimen per square meter. So we didn’t have the time to deal with the dinosaur bones discovered at the same time.”

Although a large desert now, Wang postulated that the basin was once home to a huge lake and rich vegetation, supporting billions of prehistoric animals.

One of the dinosaurs mentioned in the study, although incomplete, is thought to be of a large animal stretching over 20 meters. Researchers have named it Silutitan sinensis, after the ancient Silk Road trade route that crossed Xinjiang.

Meanwhile, the second species has been named Hamititan xinjiangensis, after the city where the dinosaur was discovered. The Hamititan is estimated to be at least 17 meters long, researchers said.

“It’s very difficult to find complete fossils of large dinosaurs,” Wang said, explaining that the Gobi Desert’s environment weathers fossils quickly.

Researchers also found several other dinosaur bones in the region, but the specimens offered scant information by which to be identified, according to the study.

Editor: Bibek Bhandari.

(Header image: Artistic rendering of Silutitan sinensis (left) and Hamititan xinjiangensis (right) with other pterosaurs and theropods. Courtesy of Zhao Chuang)