Abstract:
A new study overturns more than 150 years of conventional wisdom in academia. Scientists have discovered through ancient DNA analysis that a giant bird long thought to have gone extinct after the end of the last Ice Age was not actually an independent species that disappeared, but a large ancestor of a living bird still living in Europe today.
For a long time, large crane skeletons found in caves in many places in Europe have been regarded as the remains of an ancient giant bird called Grus primigenia. Since being named in the 19th century, the scientific community has generally believed that this large bird became extinct thousands of years ago, becoming one of the many large animals that disappeared after the end of the last Ice Age.
This traditional understanding originated from the research of French biologist Alphonse Milne-Edwards. At that time, he discovered some unusually large crane skeleton fossils in a cave in southern France. Because these fossils were significantly larger than modern cranes, he determined that they were a new species of giant crane and named it the primitive crane. The remains are believed to have lived more than 20,000 years ago, and have been documented in scientific literature as an extinct species.
In order to re-confirm the true identity of these fossils, a research team from Bournemouth University in the UK and the Paleogenetics Center in Stockholm, Sweden, launched an investigation. The researchers collected 18 ancient crane skeleton samples from England, Wales, France, Germany and the Balearic Islands, and extracted ancient DNA from them for analysis.
The findings surprised scientists. Genetic evidence shows that these skeletons, thought to be "giant extinct cranes," do not actually belong to an extinct independent species, but to large individuals of the modern Common Crane. In other words, the giant bird that was thought to have disappeared has not really become extinct. It still lives in Europe, but its size has shrunk compared to ancient times.
Professor John Stewart, the leader of the research, said that the team has always suspected that these so-called giant cranes may not be an independent species, but just a larger ancestral population of modern common cranes. The application of DNA technology finally confirmed this guess, and also allowed researchers to obtain more accurate conclusions than in the past relying solely on bone morphological analysis.
The research team believes that the misjudgment that year was likely related to the obvious gender and size differences among cranes. Male cranes are typically much larger than females, and early researchers who classified them solely by bone size may have mistaken large males and smaller individuals as belonging to two different species, leading to the conclusion that "giant extinct cranes" existed.
This discovery not only rewrote the taxonomic status of the primitive crane, but also triggered a re-examination of other extinct bird species in the scientific community. Researchers pointed out that the classification of many ancient bird species is mainly based on differences in bone size and morphology. If there is a lack of genetic evidence, some so-called extinct species may be proven to be just body variations of existing species in different historical periods.
The research team said that the next step will focus on studying why ordinary cranes gradually become smaller during the long evolutionary process. Scientists currently suspect that factors such as wetland drainage projects, changes in human land use, and habitat changes may have had an impact, but the specific mechanisms still require further research to confirm.
The researchers also pointed out that modern birds do face huge survival pressure from human activities, but this discovery shows that the academic community may have overestimated the number of bird extinctions in certain historical periods. Some birds that are considered extinct may actually just undergo long-term body size evolution, and their descendants are still living on the earth today.
This research not only solves a paleontological mystery that has lasted for a century and a half, but also demonstrates the important value of ancient DNA technology in reconstructing the history of biological evolution. As more ancient genetic information is analyzed, more "extinct" ancient animals may be re-recognized in the future, and their true identities are expected to be rewritten.
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