Spanish paleontologists find 100 million years-old beetles larvae that ate dinosaur feathers

sarahjay1 (69)memberin Popular STEM • 2 years ago

(Enrique Peñalver et al. / PNAS, 2023 https://bit.ly/3KQUL25)

A team of paleontologists led by Enrico Peñalver found beetle larvae that fed on the fallen feathers in the nests of theropod dinosaurs.

The researchers came to this conclusion after analyzing several fragments of Cretaceous amber from Spain.

Their find was the first evidence of a commensal-mutualistic relationship between non-avian dinosaurs and arthropods.

Some insects and mites feed exclusively on bird feathers. Some of them harm the owners, violating their thermal insulation and ability to fly.

However, others are harmless or even beneficial, for example, by cleaning bird nests of old feathers.

It is assumed that invertebrates learned to feed on feathers already in the Mesozoic, and initially these were feathers of non-avian dinosaurs from the theropod group.

However, until now, paleontologists have not had direct confirmation of this hypothesis.

FIRST OF ITS KIND
Now the Peñalver team from the Spanish National Institute of Geology and Mineralogy made the discovery.

The researchers focused on a sample of amber about a hundred million years old (from the Cretaceous period), which was found in the north-east of Spain and was divided into several parts during processing.

Inside the fragments, paleontologists discovered numerous fossilized feathers of an unknown theropod species - they could not belong to birds, since they had not yet appeared.

They also found tiny skins of beetle larvae, their feces and small debris discarded during molting.

Three similar and at the same time perfectly preserved skins were found in other pieces of Spanish Cretaceous amber, a little older and a little younger than the first.

After studying the skins, the researchers concluded that the insects that shed them most of all resembled the larvae of modern beetles from the skin beetle family (Dermestidae).

First of all, this is indicated by the structure of their heads and oral appendages.

The larvae of some modern skin beetles feed on feathers and other keratin integuments of vertebrates, and they often settle in bird nests.

This family already existed in the Cretaceous, as evidenced by numerous finds of larvae and adults, including in amber.

DINOS
Since all the larval skins from the first amber sample were in close proximity to dinosaur feathers, their owners most likely lived among the feathers.

The authors suggest that these insects lived in theropod nests and ate feathers that had fallen from their bodies.

Theoretically, it is possible that the skins and feathers fell into the resin independently of each other, after which they were petrified.

However, both types of inclusions are so rare in amber that the likelihood of such an event is extremely small.

Although the authors could not find significant damage to the feathers encased in amber, less significant insect jaw marks remained on some feather barbs.

Peñalver's team suggested that the beetle larvae they found were eating already fallen theropod feathers.

The fact is that traces of decomposition on the feathers enclosed in amber and the presence of coprolites indicate that these feathers had lain on the surface of the earth for some time.

Thus, these insects did not cause harm to the owners. They may even have been useful in clearing the nests of old feathers.

The results of the study provided the first evidence that a commensal-mutualistic relationship existed between arthropods and some non-avian dinosaurs during the Cretaceous.

In addition, this is another argument in favor of the idea that modern birds inherited many parasites and symbionts from non-avian dinosaurs.

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