Evrim Yazgin
Evrim Yazgin has a Bachelor of Science majoring in mathematical physics and a Master of Science in physics, both from the University of Melbourne.
Analysis of bird fossils unearthed from the “Peking Man” site show ravens, absent from Beijing today, lived alongside China’s ancient human inhabitants in the region.
Nearly 30 years ago, fossil raven bones were excavated from the cave site known as Locality 3 on the Zhoukoudian site, in an area known as Dragon Bone Hill. These fossils include a 100,000-year-old upper wing bone (humerus) and shinbone (tibiotarsus). Initially, the bones were ascribed to their own extinct species called Corvus fanshannus. But they were never compared to living ravens, until now.
Two years ago, scientists found a large, fossilised raven skull in another cave site in north-east China’s Liaoning Province. The Liaoning skull is nearly 500,000 years old.
A new analysis of the fossil bones, published in the Journal of Ornithology, compares them to those of living and extinct members of the crow family. The researchers found anatomical traits which show all these fossils are from Northern Ravens, or the Common Raven.
Common Ravens (Corvus corax) are the largest songbird in the world. Thay can be nearly 1.5 kg and have a wingspan of more than 1 metre. They are a nonmigratory bird which today can be found across the northern parts of Europe, North America and Asia. But there is no historical evidence of their presence in Beijing – until now.
The Zhoukoudian site is 42 kilometres southwest of Beijing’s centre and where “Peking Man” was discovered. Peking Man is a Homo erectusspecimen known from a complete skullcap discovered in 1929. The hominin lived about 400,000 years ago.
The site includes the largest single collection of Homo erectus fossils with 40 incomplete skeletons found. Remains of anatomically modern humans, Homo sapiens, have also been dug up at the site.
Dozens of other mammal fossils including extinct giant deer (Megaloceros pachyosteus), hyenas and sabretooth cats (Homotherium) have been found at the Zhoukoudian site.
The region 100,000 years ago, would have had a warm climate but 500,000 years ago the Liaoning site would have been cold and dry.
Corresponding author Dr Jingmai O’Connor from Chicago’s Field Museum of Natural History says that the existence of Northern Ravens in both these time periods shows the adaptability of the birds to climate changes.
“Since the Northern Raven is not a migratory species, its presence as fossils outside of its current and historic geographic range across a large part of northeastern China in Beijing and Liaoning Province, during both colder and warmer parts of the Pleistocene epoch [2.58 million to about 11,700 years ago], shows that the raven likely was resilient against climate change.”
But the finds raise the question why the Northern Raven is not found in Beijing’s warmer climates today? Lead author Dr Thomas Stidham from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences suggests that the answer may be in the food source of ravens.
“The fossils from the cave sites on Dragon Bone Hill show us that ancient Beijing was full of large animals like elephants, rhinos, and extinct horses that would have provided carrion to be eaten by local scavengers like hyenas, bears, people, and ravens. With the loss of those large animals at the end of the Pleistocene, we also see the loss of the scavengers in Beijing who ate their meat, including the raven.”
Analysing the effects of climate change and the resulting impacts on biodiversity on different species over long time intervals can help scientists assess the dangers in a new period of climate change.
“If we want to better protect birds and other organisms on our changing planet, we need studies like ours that examine the deep past during different global climates using museum fossil collections to identify key factors affecting birds and their responses over the long term,” says co-author Dr Li Zhiheng, also from the IVPP.
