CUHK palaeontologist investigates the diet of prehistoric birds to reconstruct past and present ecosystems
The early bird gets the worm – a saying that has been proven true by a palaeontology researcher from The Chinese University of Hong Kong’s (CUHK) School of Life Sciences and his team, who have identified the diet of a group of prehistoric birds. The first research team to investigate assumptions made about these birds’ diet based on quantitative fossil evidence, they discovered that a 120-million-year-old bird family called Longipterygidae, commonly believed to eat fish, fed mainly on invertebrates. The research furthers understanding of the evolution of birds and sheds light on both past and present ecosystems. The findings were published in the international journal of biology BMC Biology.
Bird are good “indicator species” in the modern world, as they are sensitive to environmental change, helping scientists to get an idea of how healthy an ecosystem is and how animals react as the environment changes over space and time. Dr. Michael Pittman, Assistant Professor from CUHK’s School of Life Sciences commented, “Birds eat just about everything today, but the origin of such a range of diets is a mystery. Understanding the diet of extinct birds is key to understanding their ecology, and in turn prehistoric ecology as a whole.”
Dr. Pittman and his team investigated the group Longipterygidae: a well-known bird called Longipteryx and its close relatives. One of the main bird families in the Cretaceous era, longipterygids had strange skulls with long jaws and teeth clustered only at the tip of the jaw. For most longipterygids, these skulls were believed to be adapted to probe for insects in mud or tree bark. The larger teeth and claws of Longipteryx, in contrast, were proposed as adaptations for eating fish.
Study refutes previous scientific assumptions about the dietary habits of longipterygids
The team investigated the ecology of over 150 living bird species, combining four separate lines of evidence – body mass, claw shape, skull bite efficiency and skull bite strength – to reconstruct the diet of longipterygid birds. The team is the first to test dietary hypotheses about the Longipterygidae family. Researchers previously believed that Longipteryx was in the habit of eating fish, but the team found that this might be inaccurate. They were most likely to feed on invertebrates like insects, or to be generalists, eating a variety of foods.
“Longipteryx birds have a smaller body mass and in particular weaker jaws than most living fish-eating birds like kingfishers. The evidence pointing to Longipteryx not being a specialist fish-eater surprised me the most, as it was previously assumed that was why they evolved such long jaws,” said Mr. Case Vincent Miller, the first author of the research and Dr. Pittman’s PhD student at the University of Hong Kong.
According to Dr. Pittman, research data suggest the diet of the longipterygid family overlapped with many different living invertebrate-eating birds. Additionally, it is commonly believed that the earliest prehistoric birds ate insects, too. This means birds in the longipterygid family were evolving their long snouts while retaining the same diet as their ancestors, which implies their strange skulls evolved for a reason other than a change in diet. The new study hypothesises that the strange jaws of longipterygids may have helped in removing parasites, cooling down their body, or enhancing their senses in some way.
“There are over 100 known species of Cretaceous birds, and we only have dietary information from less than a dozen after this study. So, there is still a lot of work to do, which includes adding additional methodologies to narrow dietary habits further, to form a more complete record of bird ecology,” Dr. Pittman said.
Mr. Miller added, “We plan to build on our work on longipterygid diet. If they did specialise in eating invertebrates, the microscopic wear on their teeth will tell us how hard or soft their food was. We may even be able to point to specific groups of insects or worms they could have specialised in hunting.”
The research team also includes Prof. Xiaoli WANG and Prof. Xiaoting ZHENG of the Shandong Tianyu Museum of Nature, and Dr. Jen A. BRIGHT of the University of Hull.
The research paper can be found at: https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-022-01294-3