A greenish oval-shaped kneecap bone and two black teeth on a black background.

A patella bone (kneecap) and two teeth are currently the only Buronius fossils that have been found. Image © Böhme et al., 2024, licensed under CC-BY 4.0 via PLOS One.

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World’s smallest great ape may have lived in Europe, researchers claim

A potential new and tiny relative of chimpanzees, gorillas and orangutans has been discovered in Germany.

While the researchers describing Buronius manfredschmidi claim it is a new species, not all scientists are convinced.

A new species of great ape may not have been alone in Europe’s ancient woodlands.

Only two primates, humans and barbary macaques, today call the continent home, but this hasn’t always been the case. In fact, a variety of different species have lived there over the past 20 million years.

The newest member of this group is Buronius manfredschmidi, a small ape discovered in the Hammerscmiede clay pit in southern Germany. While only a couple of teeth and its kneecap have been found so far, its discoverers claim that it offers new insights into Europe’s past.

Their research suggests that not only was this great ape much smaller than its modern relatives, but that it might also have lived alongside a larger species, Danuvius guggenmosi.

The researchers believe it’s the first time that fossils of different great apes have been found together in Europe, with the two species focusing on different foods to co-exist.

Professor Madelaine Böhme, the lead author of a new paper describing the species, says that further excavations might reveal more about the lives of these apes.

Buronius was probably a small leaf-eater that preferred to live in trees,” Madelaine says. “In contrast, Danuvius was likely an omnivore. It also lived in trees, but may have been able to come down and search a larger area for a variety of food sources.”

“A similar co-existence between two apes had previously only been seen in African stem apes that are more than seven million years older. It remains to be seen whether Buronius and Danuvius will remain a special case in Europe, or if similar relationships might be found.”

A baby chimpanzee sits on dirt while holding food in its hand.

Chimpanzees are one of the four groups of great apes alive today. Image © Mario Plechaty Photograph / Shutterstock.

While the researchers are confident that Buronius represents a new species, other scientists believe that naming these fossils might be premature. Among those is Professor Peter Andrews, a scientific associate of the Natural History Museum who was not involved in the research.

“It is great that new fossil ape specimens continue to be found, and comparative samples continue to improve,” Peter says. “It is the way new specimens fit into this known database that takes the subject forward.

“However, as there are very few fossils of Buronius, there is no way of knowing the degree of variability in the size differences and morphological characteristics that have been used to distinguish it from Danuvius and other apes. For this reason, it is not good practice to base a new species on such a limited number of fossils.”

The findings of the study were published in the journal PLOS One.

Europe’s ancient apes

Today, there are only four groups of great ape – orangutans, gorillas, chimpanzees and humans. In the past there were many more, especially during the Miocene between five and 23 million years ago.

Over 50 different species are known to have lived across Africa, Europe and Asia throughout this time, with their diversity peaking around nine million years ago amid a burst of speciation.

The lead up to this period isn’t well understood, however, as primate bones are relatively rare and often poorly preserved. Not only does this make it more difficult to understand their evolutionary relationships, but also whether the animals interacted while they were alive.

Just a handful of sites in Europe, including Hammerscmiede, have fossils from more than one primate. Danuvius and an unidentified monkey have previously been discovered at the site, which would have been a large floodplain 11.6 million years ago.

When animals died nearby, their remains were rapidly buried by streams and rivers crossing the site. While the flow of the water broke apart many of the skeletons, the burial in mud protected the bones from the environment and gave them a chance to fossilise.

As a result, thousands of fossils from over 100 different vertebrate species have been found at Hammerscmiede, including remains from the ancient relatives of snapping turtles, red pandas and even elephants. Buronius is the latest species to be named at the site, adding another piece to the puzzle of European primates.

An aerial photograph of a clay pit surrounded by trees with digging equipment at the base.

The bones were found in the Hammerscmiede clay pit, a rich fossil site deep in southern Germany. Public Domain image by Thomas Springer from Wikimedia Commons.

Is Buronius really a species?

While the fossils of Buronius were found in the same layer of soil as Danuvius, the authors of the study say they have identified a number of differences. The kneecap appears to be smaller and thicker than many other early apes, while the teeth are a different shape.

“The morphology of the two known teeth of Buronius differ greatly from previously known fossil apes,” Madelaine explains. “In particular, the pattern of enamel on the chewing surface of the teeth is very different, while they are significantly smaller than the teeth of all known crown apes.”

“While the milk teeth of other apes might have a similar size range to these teeth, the teeth of Buronius are permanent teeth. The adult teeth of mammals don’t change size as they age, which means that they must have come from a small ape.”

Peter, however, is keen to remain cautious about the study. While he hasn’t seen the fossils directly, he says that the authors need more evidence to back up their findings.

“One site where more than one hominid species has been found is Paşalar in Turkey, where it took eight years of collecting and 31 years of study to be certain there was a second species,” Peter explains. “We could only do so once the observed phylogenetic differences could be linked with differences in development and ecology.”

“One of the species found at Paşalar is Griphopithecus alpani. While the single molar of Buronius is said to be smaller than Griphopthecus, it in fact falls well within the known range of variation of the 78 Griphopthecus specimens found in Paşalar.”

Settling the debate over Buronius will likely only be settled by the discovery of more fossils. Though past clay mining at Hammerscmiede has meant many bones have been damaged already, Madelaine is hopeful more will turn up.

“While many ape remains have been irretrievably destroyed by mining, the layers where the Buronius and Danuvius finds were made has been protected since 2020,” Madelaine says. “I am therefore very confident that we will be able to make further exciting finds of both species in the coming years.”