China continues to be a land of mystique and wonder, with many facets of its culture and society yet to be fully understood. But it is also a country known for amazing dinosaur fossils and the latest find is extraordinary! At a prehistoric animal graveyard in Gansu, northwestern China, an enormous ancestor to the modern-day rhinoceros has been discovered. It now being called “the largest rhino ever.” The remains of this 26.5-million-year-old giant, hornless rhino have been detailed in a fantastic open-access study published in the journal Communications Biology, conducted by the Chinese Academy of Sciences, Beijing.
Around 26.5-million-years ago, during the Oligocene epoch (33.9 mya-23.03 million years ago or mya) the world’s largest rhino ever lived in this area of China at the northern edge of the Tibetan Plateau. The beginning of the Oligocene period, incidentally, is marked by an extinction event called the Grand Coupure, where European mammalian fauna was dramatically replaced by Asian fauna. Essentially, due to climate change, some of the earliest polar glaciations occurred leading to global cooling and marked drying conditions, causing a fall in sea-levels. During this time, a global expansion of grasslands also occurred, and tropical broad leaf forests began coalescing around the equatorial line.
Panorama of the lower Daxia River valley, seen from the edge of the loess plateau in northeast Linxia County. On the right, one can see part of the plateau and a canyon cutting thru it. The near side of the river is in Linxia County (Hexi Township), the far side, in Dongxiang County (Hetan Town). This is where China’s famous Linxia animal graveyard is located and where the remains of the largest rhino ever were unearthed. (Vmenkov / CC BY-SA 3.0)
World’s Largest Rhino Ever and the Linxia Animal Graveyard
The Linxia animal graveyard, at the foot of the northeastern border of the Tibetan Plateau, has long been a source of fascination for the local people.
From the 1950s, farmers have been discussing what they call “dragon bones,” according to lead researcher and author of the study, Deng Tao, director and professor at Beijing’s Institute of Vertebrate Paleontology and Paleoanthropology (which is part of the Chinese Academy of Sciences).
Institutionalized digging began in the 1980s, but a combination of luck and technology only yielded rare, but fragmented giant rhino fossils. In 2015, however, the complete skull and jaw from one giant rhino, and three vertebrae from another were found and dated to the Oligocene period. “The bones’ completeness and huge size were a great surprise for us,” said Professor Tao. Immediately analysis revealed that the fossils were larger than anything that had been previously discovered .
Indricotherium (Indricotherium), scanned from a website November 2, 2010. A life-size model of Indricotherium, the largest land mammal ever discovered, peeks at visitors at the entrance of “Extreme Mammals: the Biggest, Smallest and Most Amazing Mammals of All Time,” an exhibit held at the Cleveland Museum of Natural History. Like Paracatherium linxiaense, the world’s largest rhino species to date, Indricotherium remains were also found in the Linxia animal graveyard in China. (Denis Finnin / American Museum of Natural History)
Paracatherium Linxiaense: The Giant Herbivore Rhino
In fact, the 26-foot-long (8-meter-long) herbivorous beast had a shoulder height of 16.4 feet (5 meters), and it weighed as much as 24 tons (21.7 metric tons), the same as four African elephants! The newly identified species has been coined Paraceratherium linxiaense, in reference to the Linxia Basin in Gansu province, where it was found. The Daily Mail reports that “the bizarre animal had a slender skull, short trunk and an unusually long and muscular neck,” and Tao described it as a “friendly giant.”
“Its prehensile nose trunk was extremely useful to wrap around branches – allowing the sharp front teeth to strip off the leaves. Its tusk-like incisors are primarily used to break twigs and strip bark, as well as to bend higher branches,” said Professor Deng. The evolution and adaptation of the skull and legs are longer than all land mammals, making it ideal for open woodlands under both dry and humid conditions.
Figure 1 from the recently published study in the Communications Biology journal. Skull: a lateral view; b ventral view; c dorsal view; d anterior view; e occipital view. Mandible: f, h lateral view and medial view of left ramus, respectively; g occlusal view. Skull and mandible share the scale bar, but both anterior and nuchal views have an independent scale bar. (Communications Biology journal)
Migration and Extinction of World’s Biggest Rhino Ever
At this point in the Oligocene period, the Tibetan region was not the elevated plateau it is today. This became a focal point of the study, as the migratory patterns of the P. linxiaense were understood and refined. If its height had been what it is today, it would have deterred those species making the journey from China towards the Indian subcontinent.
“Through to the late Oligocene, the evolution and dispersal of the giant rhino demonstrate Tibet, as a plateau, did not exist and was not yet a barrier to the largest land mammals,” according to Professor Deng. Other palaeo archaeological evidence also backs this theory: fish and plant fossils from this period and region display tropical and sub-tropical characteristics.
The Paraceratherium is closely linked to the giant rhinoceros of Pakistan, suggesting a linkage and cross-migration, though it isn’t fully clear yet when and why this occurred. Yet, we can safely say that it did pass through the Tibetan region and reached the Indian subcontinent between 34 and 23 million years ago. For this to occur, the Tibetan region was probably under 6,500 feet (1,980 m) above sea level, as the researchers surmised (compared to the average elevation of 4,000m or 13,000 feet today).
Ultimately, the largest rhino ever was probably wiped out as a consequence of climate change, disease and death by giant predators. While it may be difficult to imagine, these enormous rhinos were hunted by gigantic crocodiles and dog-bears called Hemicyon. There is also the possibility that the arrival of another herbivore triggered ecological changes to such an extent that this great beast was driven to extinction.
