Molt remains of feather-feeding beetle larvae intimately associated with downy feather portions from an unidentified theropod dinosaur in Early Cretaceous amber of Spain. Insets show the head with powerful mandibles of one of the larval molts (top) and the pigmentation pattern of feather second order branches (bottom), with the main stem of one feather at the right of the amber fragment. Amber fragment is only six millimeters across. Credit: CN IGME-CSIC
Phys.org has a story about an discovery in Mesozoic amber. The amber reveals a parasitic beetle feeding on some feathers. The researchers were unable to determine if the relationship was one of mutual benefit or one-sided. The amber is about 105 million years old from a Spanish locality near San Just. The paper was published in the journal PNAS.
The main amber fragments studied, from the Spanish locality of San Just (Teruel), contain larval molts of small beetle larvae tightly surrounded by portions of downy feathers. The feathers belonged to an unknown theropod dinosaur, either avian (a term referring to "birds" in wide sense) or non-avian, as both types of theropods lived during the Early Cretaceous and shared often indistinguishable feather types. However, the studied feathers did not belong to modern birds since the group appeared about 30 million years later in the fossil record, during the Late Cretaceous.
When looking at modern ecosystems, we see how ticks infest cattle, frogs capture insects with acrobatic tongues, or some barnacles grow on the skin of whales. These are just a few of the diverse and complex ecological relationships between vertebrates and arthropods, which have coexisted for more than 500 million years. The way that these two groups have interacted throughout deep time is thought to have critically shaped their evolutionary history, leading to coevolution. Nevertheless, evidence of arthropod-vertebrate relationships is extremely rare in the fossil record.
