Vertebrates and arthropods are two of the most successful and frequently fossilized animal groups, but direct evidence of their interaction in deep time — entailing the joint, intimate fossilization of remains from both groups — is extremely rare. New discoveries in Early Cretaceous amber from the locality of San Just in north-eastern Spain show that a symbiotic relationship, likely commensal/mutualistic, was established between beetle larvae feeding on detached feathers and feathered non-avian dinosaurs more than a hundred million years ago.
“Feathers, like hair, are integumentary structures composed of tough, durable keratin,” said Dr. Ricardo Pérez-de la Fuente from the Oxford University Museum of Natural History and his colleagues.
“Despite being a concentrated source of this protein, few groups of arthropods have evolved adaptations to ingest and metabolize keratin — the so-called keratophagy.”
“Aside from its ecological significance, keratophagy is important from an evolutionary standpoint as well, representing, for example, a transitional stage between free-living bark lice and true parasitic lice, in the form of scavenging book lice that commonly feed on nest debris, including keratin.”
“Keratophagy as a trophic specialization entails a parasitic symbiosis if the feeding arthropod guest causes damage in the integument of the vertebrate host.”
“On the contrary, keratophagy can also involve a commensal-mutualistic symbiosis between the host and the arthropod consuming the host’s shed, accumulated integumentary structures, possibly advantageous to the host by cleaning its nest.”
“We present assorted evidence of keratophagy involving beetle and feather remains preserved in Cretaceous amber from Spain, representing a rare instance of arthropod-dinosaur symbiotic relationship in deep time.”
The larval molts preserved in the 105-million-year-old amber from the San Just locality were identified as related to modern skin…
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