Modern birds have evolved diverse dietary habits, able to extract nutrients from various food sources. A recent study by Assistant Professor Man Chi Man's team at the Faculty of Life Sciences, The Chinese University of Hong Kong (CUHK), published in eLife, reveals that as early as 120 million years ago, 30 million years before the ancestors of modern birds appeared, the suborder Enantiornithes had already developed highly diverse dietary habits. By further analyzing the similarities between Enantiornithes and modern birds, the study enhances our understanding of the factors contributing to the successful evolution of modern birds.
Enantiornithes were common birds in the dinosaur era. The research team focused on the Bohaiornithidae within the Enantiornithes, known for their curved large claws and robust teeth. Previously, it was believed that they hunted prey with their claws and crushed hard food with their beaks. However, the study found that the dietary habits of Bohaiornithidae were more complex and varied.
Quantitative comparisons were made by the research team regarding the body weight, claws, skull shape, and skull mechanics of Bohaiornithidae and over 9,000 modern bird species. They discovered that different bird species within Bohaiornithidae had varied dietary habits, some resembling carnivores, some closer to herbivores, and others being omnivorous, showcasing a more complex dietary spectrum.
"A common feature among various Bohaiornithidae birds is their thick and robust jawbone structure. Animals with strong jawbones typically have more food choices, being able to handle both soft and hard foods; whereas animals with weaker jawbone strength cannot consume hard foods. Other Enantiornithes like the Longipterygidae have the weakest jawbone strength, hence having the fewest food options; while the Hesperornithidae have moderate jawbone strength, offering slightly more dietary variety than the former. Compared to these two suborders, Bohaiornithidae possess a stronger and more powerful jawbone structure, enabling them to consume a wider range of foods, leading to a more diversified development compared to other early bird species," explained Dr. Jen Bright, a co-author of the paper from the University of Hull, UK.
Furthermore, based on existing data, the research team estimated that from the appearance of ancient Enantiornithes around 145 million years ago until about 120 million years ago, it took 25 million years for Enantiornithes to evolve diverse dietary habits. On the other hand, genetic research results indicate that the ancestors of modern birds also spent at least 25 million years evolving their current dietary diversity.
The research team speculates that powered flight is the most likely common factor for both groups evolving diverse diets. While powered flight can provide significant advantages for individual organisms in survival, how these advantages accumulate evolutionarily across generations remains unknown, presenting a new area in urgent need of research.
In the future, the research team aims to further investigate why birds and Enantiornithes have such similar dietary evolution and explore the significance of this evolutionary history for contemporary ecological conservation efforts.
For more information on the related paper, visit: https://doi.org/10.7554/eLife.89871.3
The ancient bird species depicted in the image are Bohaiornis (center), Changyuraptor (left), and Pelagornis (right). Image provided by the University of Hong Kong.
