Scientists at Bournemouth University (BU) have solved a 150-year-old mystery by successfully identifying the ancient remains of a 20,000-year-old crane as an ancestor of modern cranes. The new finding refutes the bird’s initial 19th-century classification, suggesting the bone fragments belonged to a separate, extinct crane species.
The research team behind the new ancient crane identification said that future efforts will focus on why cranes have shrunk so much over time. The team also noted that the approach used to solve the mystery could help identify other ancient remains using bone DNA samples.
150-Year-Old-Mystery & the DNA of a 20,000-Year-Old Crane
According to a statement announcing the findings, French biologist Alphonse Milne-Edwards first discovered the 20,000-year-old crane remains in caves in southern France. Using standard geological and palaeontological techniques, the research team correctly dated the crane’s existence and demise to sometime around the end of the last ice age.
Since more advanced DNA analysis was not available in the 1800s, scientists relied on shape, size, and other morphological characteristics to determine what sort of ancient bird bones they were looking at.
“Previous studies had merely used the size and shape of the bones to attempt to understand these large birds,” explained Dr. John Stewart, Professor of Evolutionary Palaeoecology at BU and leader of the research team
According to the BU team, that analysis resulted in the widespread belief that “these bones were from an extinct species of giant crane.” This determination also earned it the name Grus Primigenia. Still, Dr. Steward said modern researchers have begun to suspect that G. primigenia and similarly dated large ancient cranes discovered in the region were not from an extinct species, but instead represented a subset of “larger, modern European common cranes.”
DNA Confirms Crane Was Not an Extinct Species
To solve the 150-year-old mystery, Dr. Steward joined forces with the Centre for Palaeogenetics in Stockholm, Sweden to examine ancient DNA samples from 18 crane bones. Along with the Grus samples, they also examined DNA from similarly aged crane bones discovered in England, Wales, France, Germany and the Balearic Islands.
After extracting DNA from all 18 samples, the team sequenced the ancient animals’ DNA. According to Dr. Steward, this analysis provided the team with a “more accurate picture of what they represent.”
As suspected, the 20,000-year-old crane bones were not from an extinct ancient species. Instead, the team said these tests revealed that the bones are “larger versions of the current common crane we see in Europe today.” Dr. Stewart said the reason for the 150-year-old misidentification came down to different sizes and not different species.
“We believe that the reason for the mistaken identity was that cranes have large males and smaller females,” the researcher explained. “There were two different species – the living, common crane we see today and the extinct, larger species.”
Method Could Solve Other Species Identification Mysteries
Next, the BU team plans to explore why modern cranes decreased in size over the last 20,000 years. Steward said he suspects the primary culprits may be Wetland drainage and human land-use changes, adding that “more work is needed to resolve” the mystery once and for all.
“While it is true that many species of birds are vulnerable to human actions today, it may be that we have overestimated the number of extinctions in the past,” said Dr Stewart. “Some of these may instead represent size changes to living species”
When discussing the benefits of their findings beyond this specific 150-year-old mystery, the team said the findings show that extracting DNA from extinct species is a viable method of species identification.
“It may be that other extinct bird species which have been identified solely using size differences are problematic,” they explained, adding that “an ancient DNA investigation may be required to confirm these identities.”
Christopher Plain has spent the last six years as Associate News Editor and Head Science Reporter at The Debrief. Follow and connect with him on X, learn about his novels at plainfiction.com, or email him at christopher@thedebrief.org.