Beetles may have fed on the feathers of dinosaurs about 105 million years ago, fossils in amber have revealed.
The main amber fragments studied contain the shed skin (larval moults) of small beetle larvae tightly surrounded by portions of downy feathers.
Researchers said the feathers belonged to an unknown theropod dinosaur, either avian (bird) or non-avian, as both types of theropods lived during the early Cretaceous period and shared often indistinguishable feather types.
However, the feathers did not belong to modern birds since that group appeared about 30 million years later in the fossil record.
“This is hard evidence that the fossil beetles almost certainly fed on the feathers and that these were detached from its host.
“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.”
The larval moults preserved in the amber, from the Spanish locality of San Just, in Teruel province, were identified as related to modern skin beetles, or dermestids.
They are known pests of stored products or dried museum collections, feeding on organic materials that are hard for other organisms to break down such as natural fibres.
According to researchers, dermestids also play a key role in the recycling of organic matter in the natural environment, commonly inhabiting nests of birds and mammals, where feathers, hair, or skin accumulate.
Dr Ricardo Perez-de la Fuente, from Oxford University Museum of Natural History, and co-lead author of the study, said: “It is unclear whether the feathered theropod host also benefited from the beetle larvae feeding on its detached feathers in this plausible nest setting.
“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.”
The findings are published in the Proceedings of the National Academy of Sciences journal.