Paleontologists in Bulgaria have described a new species of the panda genus Agriarctos, from two fossilized teeth dating to 5.5 million years ago.
Life reconstruction of Agriarctos nikolovi. Image credit: Velizar Simeonovski.
The newly-described panda species lived in what is now Bulgaria during the Turolian age of the Miocene epoch.
Named Agriarctos nikolovi, the ancient bear is currently the last known and ‘most evolved’ European panda species.
It was up to 2 m (6.6 feet) long, comparable in size to the largest individuals of the living giant panda (Ailuropoda melanoleuca).
Unlike today’s iconic black and white bear however, Agriarctos nikolovi was not reliant on purely bamboo.
“Although not a direct ancestor of the modern genus of the giant panda, Ailuropoda, it is its close relative,” said Professor Nikolai Spassov, a paleontologist at Bulgaria’s National Museum of Natural History.
“This discovery shows how little we still know about ancient nature and demonstrates also that historic discoveries in paleontology can lead to unexpected results, even today.”
The two isolated teeth (an upper carnassial tooth and an upper canine) of Agriarctos nikolovi were found in the 1970s near the village of Ognyanovo in Sofia county, Bulgaria.
The coal deposits in which the specimens were found suggest that this species inhabited forested, swampy regions.
Fossils of the staple grass that sustains the modern panda are rare in the Late Miocene of Europe — and, especially, of Bulgaria — fossil record and the cusps of the teeth do not appear strong enough to crush the woody stems.
Instead, it likely fed on softer plant materials — aligning with the general trend toward increased reliance on plants in this group’s evolutionary history.
“The likely competition with other species, especially carnivores and presumably other bears, explains the closer food specialization of giant pandas to vegetable food in humid forest conditions,” Professor Spassov said.
Professor Spassov and his colleagues, Dr. Qigao Jiangzuo, propose that Agriarctos nikolovi became extinct as a result of climate change, probably because of the Messinian salinity crisis — an event in which the Mediterranean basin dried up, significantly altering the surrounding terrestrial environments.
“Giant pandas are a very specialized group of bears,” Professor Spassov said.
“Even if Agriarctos nikolovi was not as specialized in habitats and food as the modern giant panda, fossil pandas were specialized enough and their evolution was related to humid, wooded habitats.”
“It is likely that climate change at the end of the Miocene in southern Europe, leading to aridification, had an adverse effect on the existence of the last European panda.”
The discovery of Agriarctos nikolovi is reported in a paper in the Journal of Vertebrate Paleontology.
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Qigao Jiangzuo & Nikolai Spassov. A Late Turolian giant panda from Bulgaria and the early evolution and dispersal of the panda lineage. Journal of Vertebrate Paleontology, published online July 31, 2022; doi: 10.1080/02724634.2021.2054718
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