Fossilized teeth originally found in the 1970s actually belong to a close and quite important new relative of the modern giant panda.
A new species of panda has been discovered by scientists who say it is currently the last known and “most evolved” European giant panda. It passed through the forested wetlands of Bulgaria about six million years ago.
Unearthed from the bowels of the Bulgarian National Museum of Natural History, two tooth fossils originally discovered in the Eastern European nation in the late 1970s provide new evidence of an important giant panda relative modern. Unlike today’s iconic black-and-white bear, however, he didn’t depend solely on bamboo for his sustenance.
“Although it is not a direct ancestor of the modern genus giant panda, it is its close relative,” says the Museum’s Professor Nikolai Spassov, whose findings are published today (August 1, 2022) in the journal peer-reviewed Journal of Vertebrate Paleontology.
“This discovery shows how little we still know about ancient nature and also demonstrates that historical discoveries in paleontology can lead to unexpected results even today.”
The teeth, an upper carnassial tooth and an upper canine, were originally cataloged by paleontologist Ivan Nikolov. He added them to the museum’s trove of fossilized treasures after they were discovered in northwestern Bulgaria decades ago. This new species is called Agriarctos nikolovi in his honour.
“They only had one vaguely handwritten label,” Professor Spassov recalls. “It took me many years to figure out what the locality was and how old it was. Then it also took me a long time to realize that it was an unknown fossil giant panda.
The coal deposits in which the teeth were found – which imbued them with a blackened hue – suggest that this ancient panda inhabited forested and swampy regions.
There, in the Miocene era, he probably ate a diet that was largely vegetarian – but not solely dependent on bamboo!
Fossils of the basic grass that sustains the modern panda are rare in the European fossil record, especially from the late Bulgarian Miocene. Also, the cusps of the teeth don’t seem strong enough to crush the woody stems.
Instead, it probably fed on softer plant material, consistent with the general trend of increased reliance on plants in the evolutionary history of this group.
Sharing their environment with other large predators likely pushed the giant panda line toward vegetarianism.
“Likely competition with other species, particularly carnivores and presumably other bears, explains the closer food specialization of giant pandas compared to plant food in rainforest conditions,” says Professor Spassov.
A.nikolovi‘s teeth nonetheless provided sufficient defense against predators, the paper speculates. Additionally, the canines are comparable in size to those of the modern panda, suggesting that they belonged to a similarly sized or slightly smaller animal.
The authors suggest that A.nikolovi may have disappeared as a result of climate change, possibly due to the “Messinian salinity crisis”. This event, during which the Mediterranean basin dried up, considerably modified the surrounding land environments.
“Giant pandas are a very specialized group of bears,” adds Professor Spassov. “Even though A. niklovi was not as specialized in habitats and food as the modern giant panda, fossil pandas were sufficiently specialized and their evolution was linked to moist and forested habitats. It is likely that climate change at the end of the Miocene in southern Europe, leading to aridification, had a detrimental effect on the existence of the last European panda.
Co-author Qigao Jiangzuo, of Peking University, China, was primarily responsible for helping narrow down the identity of this strange beast to belonging to the Ailuropodini – a tribe in the bear family Ursidae. While this group of animals is best known by its sole living representative, the giant panda, they once roamed Europe and Asia. Curiously, the authors propose two potential routes for the distribution of this group.
One possible evolutionary trajectory is for the Ailuropodini to leave Asia and end in A.nikolovi in Europe. However, Professor Spassov adds caution to this assumption, saying that paleontological data shows that “the oldest members of this group of bears have been found in Europe”. This suggests that the group may have developed in Europe and then moved on to Asia, where the ancestors of another genus, Ailurarctos, developed. These early pandas may have later evolved into Ailuropods—the modern giant panda.
Reference: “Discovery of a Late Turolian giant panda in Bulgaria and early evolution and dispersal of the panda lineage” August 1, 2022, Journal of Vertebrate Paleontology.
Funding: Second Tibetan Plateau Scientific Expedition and Research, Chinese Natural Science Foundation Program, Chinese Academy of Sciences Strategic Priority Research Program, Chinese Academy of Sciences Key Frontier Scientific Research Program