Beetles fed on dinosaur feathers 105 million years ago

Newly discovered amber fossils have provided intriguing evidence that beetles fed on the feathers of dinosaurs around 105 million years ago. This suggests a symbiotic relationship between the two species. 

The study, published in the Proceedings of the National Academy of Sciences, analyzed amber fragments from the San Just locality in Teruel, Spain. These fragments contained larval moults of small beetle larvae closely surrounded by pieces of downy feathers.

Scientists think the feathers belonged to an unknown theropod dinosaur. It may have been either avian or non-avian. Both types lived during the Early Cretaceous period and had similar feather types. The fossils predate the emergence of modern birds by approximately 30 million years.

Vertebrates and arthropods have coexisted for over 500 million years, forming diverse and complex ecological relationships. These interactions have critically shaped their evolutionary history and led to coevolution. However, fossil evidence of such relationships is exceedingly rare.

Researchers identified the larval moults found in the amber as related to modern dermestid beetles. These are known for feeding on organic materials that are difficult for other organisms to decay, such as natural fibers. 

Dermestids also play a crucial role in recycling organic matter in nature. They commonly inhabiting nests of birds and mammals where feathers, hair, or skin accumulate. This discovery provides valuable insights into the ecological interactions and coevolution of beetles and dinosaurs during the Early Cretaceous period.

How the study was done

“In our samples, some of the feather portions and other remains – including minute fossil faeces, or coprolites – are in intimate contact with the moults attributed to dermestid beetles and show occasional damage and/or signs of decay. This is hard evidence that the fossil beetles almost certainly fed on the feathers and that these were detached from its host,” explained Dr. Enrique Peñalver, from the Geological and Mining Institute of Spain of the Spanish National Research Council (CN IGME-CSIC) and lead author of the study. 

“The beetle larvae lived − feeding, defecating, moulting − in accumulated feathers on or close to a resin-producing tree, probably in a nest setting. A flow of resin serendipitously captured that association and preserved it for millions of years.” 

“Three additional amber pieces each containing an isolated beetle moult of a different maturity stage but assigned to the same species were also studied, allowing a better understanding of these minute insects than what is usually possible in palaeontology,” said study co-author Dr. David Peris, from the Botanical Institute of Barcelona.

Scientists found the most impressive, complete specimen in the amber deposit of Rábago/El Soplao in the northern Spain. It is roughly of the same age as San Just. 

“It is unclear whether the feathered theropod host also benefited from the beetle larvae feeding on its detached feathers in this plausible nest setting,” said co-lead author Dr. Ricardo Pérez-de la Fuente from the Oxford University Museum of Natural History. 

“However, the theropod was most likely unharmed by the activity of the larvae since our data show these did not feed on living plumage and lacked defensive structures which among modern dermestids can irritate the skin of nest hosts, even killing them.” 

Evidence that birds descended from dinosaurs

There is substantial evidence supporting the idea that birds descended from theropod dinosaurs, a group of bipedal, mostly carnivorous dinosaurs. This evidence comes from various fields, including paleontology, comparative anatomy, and molecular biology. Some key pieces of evidence are:

Fossil evidence

Researchers have discovered numerous fossils that show transitional features between dinosaurs and birds. One of the most famous examples is Archaeopteryx. It was a creature that lived around 150 million years ago and had features of both dinosaurs and birds. It had feathers and wings, but also teeth, a long bony tail, and other dinosaur-like characteristics.

Feathered dinosaurs

The discovery of numerous theropod dinosaurs with feathers or feather-like structures further supports the link between birds and dinosaurs. Examples include Velociraptor, Sinosauropteryx, and Microraptor. These findings suggest that feathers originally evolved for purposes other than flight, such as insulation or display, and were later adapted for flight in birds.

Skeletal similarities

Birds and theropod dinosaurs share many anatomical features. These include a wishbone (furcula), a unique ball-and-socket wrist joint, hollow bones, and a similar hip structure (with a pubis bone pointing backward). These shared characteristics suggest a common ancestry.

Nesting behavior

Fossil evidence indicates that some theropod dinosaurs, like the oviraptorosaurs, displayed nesting behaviors similar to those of modern birds. They built nests and brooded their eggs, providing further evidence of a connection between birds and dinosaurs.

Molecular evidence

Genetic studies have shown that birds are more closely related to certain theropod dinosaurs than these dinosaurs are to other reptiles. This supports the idea that birds are not merely related to dinosaurs. Most think they are, in fact, a subgroup of theropod dinosaurs.

Taken together, this evidence from various fields paints a compelling picture of the evolutionary link between birds and theropod dinosaurs. Scientists consider birds the only surviving lineage of dinosaurs.

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