The giant rhinoceros was the largest land mammal to ever exist on the face of the Earth and was found primarily in Asia, especially China, Mongolia, Kazakhstan, and Pakistan. How the genus Paraceratherium spread across Tibet was long a mystery. Now a new species, dubbed Paraceratherium linxiaense , identified in northwest China, has shed light on this process.
A giant ancestor of the rhinoceros
Modern rhinos are descendants of even larger creatures, estimated to have weighed about 24 tons and stood nearly 5 meters. Their heads were probably as tall as those of giraffes and weighed two to three times as much as an African elephant, like eight white rhinos. The discovery of one of these prehistoric giant rhinos on the edge of the Tibetan plateau has helped fill in the gaps in their family tree.
Until now, examples of Paraceratherium had been found in large areas of Asia, but they were generally so fragmented that it has been difficult to determine which represented common species and which evidenced a different species.
The new specimen was a hornless herbivore that roamed Asia 26.5 million years ago, scouring forests for leaves, soft plants and shrubs and resembled a ‘huge tapir’, according to the team at the Academy of China Sciences in Beijing.
The strange animal had a slender skull, a short trunk, and an unusually long and muscular neck, being, in general, a “friendly giant”.
“Its prehensile nose trunk was extremely useful for wrapping the branches, allowing the sharp front teeth to tear off the leaves,” comment the authors, who publish their study in the journal Communications Biology . “Their fang-shaped incisors are used primarily for breaking twigs and stripping bark, as well as for bending higher branches.”
The gigantic animal was identified from a perfectly preserved skull, jaw and atlas (first cervical vertebra of the spinal column that supports the head).
“The extraordinary thing about this particular thing is that it is a wonderfully preserved fossil, so it tells us a lot about the anatomy of the individual group,” said Lawrence Flynn, a co-author of the study. “To support an animal of that size, there must be a lot of vegetation,” Flynn said. “What we see in terms of vegetation globally today is not an accurate picture of what it was in the past because there was higher productivity of vegetation in the past.”
It is the last known species of a group of giant hornless rhinos that lived in Central Asia from about 50 million years ago to 23 million years ago. The home of this species appears to have been Central Asia, but the first Paraceratherium species found, P. bugtiense , lived in what is now western Pakistan. How exactly it got to the Indian subcontinent is unknown.
In each location, the genus appears to have become highly specialized in its environment, leading to branching of various species during the Oligocene between 34 and 23 million years ago. The team’s phylogenetic analysis places P. linxiaense somewhere in the middle of this transition , just before the giant rhinos made their way through Tibet. During this time, the Tibetan plateau may have been home to a landscape full of forests and open environments; a place where these huge creatures would have had no trouble feeding and thus supporting the theory that the Tibetan region was not yet the lofty plateau it is today.
Thus, like other Paraceratheriums , the researchers believe that P. linxiaense lived in large forests where it could reach the treetops without problem, to cope with the enormous volume of plants and leaves to satiate its stomach.
Referencia: Deng, T., Lu, X., Wang, S. et al. An Oligocene giant rhino provides insights into Paraceratherium evolution. Commun Biol 4, 639 (2021). https://doi.org/10.1038/s42003-021-02170-6
