This fossil represents the oldest leaf-eating bird
Reconstruction of the extinct early Cretaceous tree-dwelling vegetarian bird, Jeholornis, eating leaves. Credits: IVPP
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We know that angiosperm plants became the dominant plant group in terrestrial ecosystems from the early to middle Cretaceous. This timing also coincides with the time of the first pulse of bird diversification. But while the close relationships between birds and these plants are commonplace today, the documentation of the evolutionary origins and the construction of this ecological complexity still remains very vague, hence the interest of this study.
A fossil bird named Jeholornis
Discovered in the geological formation of Jiufotang, China, Jeholornis is an extinct genus of primitive bird belonging to the family Jeholornithidae. These animals would have lived during the Lower Cretaceous, around 120 to 122 million years ago . They also represent a milestone in the evolution of birds, showing both avian and reptilian characteristics.
Physically, these birds had a size of about thirty centimeters in length . They possessed well-developed wings, which suggests that they were capable of flight, although their flight abilities were probably more limited than those of modern birds. The presence of claws on their wings also suggests that these primitive birds could perch on tree branches.
As for their diet, paleontologists had suspected for several years that they mainly consumed plants. This new work published in the journal Nature Communication confirms this hypothesis.
Hundreds of Phytoliths
For this study, researchers from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences performed a microscopic analysis of fossilized remains in the stomach of a juvenile specimen .
The team aimed to find phytoliths . These rigid microscopic structures made of opaline silica (silicon dioxide) are produced by plants inside and between their cells. After treating the tiny samples with acid and other chemicals to remove almost anything that isn't a phytolith, the researchers recovered hundreds of them . Also, similar samples of the rock surrounding the skeleton yielded no phytolith remains. This confirms that those recovered were part of the bird's diet.
The 120 million year old fossil skeleton with the feathers still visible. There are also some microscopic fossil phytolith remains from his last meal extracted from the remains of his stomach from the bird. Credits: IVPP
Earliest Evidence of Leaf Eating in Birds
After comparison with more than 4,000 types of modern phytoliths, it also emerged from this analysis that this bird consumed tree leaves from a group of flowering plants called magnoliids which includes living magnolia, cinnamon and avocado. .
Finally, paleontologists compared this bird's lower jaw to living birds with a wide range of diets. Again, this work showed similarities to forms of living birds that primarily eat plants, including the hoatzin ( Opisthocomus hoazin ), a bird found primarily in humid regions of South America, with some characteristics reminiscent of birds fossils and reptiles.
Overall, this study details the oldest evidence of birds eating leaves. So, very early in their evolution, these animals obviously shifted from predatory behaviors to using their wings to fly up trees so they could eat the fruits, seeds and leaves of plants like so many species do today. today.
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