If you are wandering Bulgaria, you wouldn’t expect to see a panda. But, 6 million years ago this may have been a common occurrence in the forested wetlands. A newly discovered species has been uncovered from fossil teeth found in a museum and is the last known and “most evolved” European giant panda. 

Now described in the Journal of Vertebrate Paleontology, like all fun archaeology discoveries, this breakthrough came from samples that had been hidden in the depths of the archives, in this case in the Bulgarian National Museum of Natural History. The samples were two fossils of teeth (upper carnassial and upper canine) originally found in the eastern European nation in the 1970s that proved to be a sizeable relative of the modern giant panda. 

The teeth were unearthed in northwestern Bulgaria, and originally catalogued by paleontologist Ivan Nikolov, before they were sent to the depth of the museum with the rest of the fossilized treasures. As such, the new species was named in his honor – Agriarctos nikolovi.

“They had only one label written vaguely by hand,” said Professor Nikolai Spassov in a statement.  “It took me many years to figure out what the locality was and what its age was. Then it also took me a long time to realize that this was an unknown fossil giant panda.”

“Although not a direct ancestor of the modern genus of the giant panda, it is its close relative,” he added. “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.”

Despite these samples only being two teeth, a lot can be determined. The coal deposits in the teeth suggested that the ancient panda lived in forested, swampy regions. It likely consumed a largely vegetarian diet, but one difference compared to the modern panda, was that this panda did not rely solely on bamboo. Fossilized bamboo sampleS are rare from the late Miocene era in Bulgaria, indicating it wasn't abundant, and the teeth of A. nikolovi do not seem to be strong enough to crush the woody stems.

It is thought that these pandas are more likely to have fed on softer plant materials. It is also thought that these Giant European Pandas also shared their environment with large predators, which could have been a factor in turning these pandas towards vegetarianism. 

“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,” said Spassov.

Despite the vegetarian diet, these pandas were no weaklings, and their teeth could have provided a defense against other roaming predators. The teeth are also similar in size to modern pandas', suggesting they were of similar body size or slightly smaller.

So, what happened to these ancient pandas? The paper speculates that extinction could have been due to climate change. Specifically, the Messinian salinity crisis, which was when the Mediterranean basin dried up and altered the surrounding terrestrial environments. 

“Giant pandas are a very specialized group of bears,” Professor Spassov added. “Even if A. niklovi 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 evolutionary history is currently uncertain, but this information may indicate that this group of pandas could have developed in Europe and then ended up in Asia.