A 47-Million-Year-Old Owl Fossil Still Holds Its Last Meal
The young owl's stomach held a shiny cockroach, a clue that owls were hunting in daylight long before they became creatures of the night.
A young owl that lived 47 million years ago was preserved so completely that its last meal is still inside it. That meal, a shiny cockroach, is a clue that this bird hunted in daylight, which means owls only took up the night shift later on.
A hunter less than five inches long
The fossil was dug out of the Messel Pit in Germany in 2025. The pit is what is left of an ancient lake ringed by forest, and it is now the richest fossil site in the world for understanding life during the Eocene epoch, a stretch of time that ran from 56 million to 34 million years ago.
The owl's skull is missing, but almost everything else survived in remarkable condition, right down to the contents of its stomach. The bird was a youngster, a fledgling, and it was tiny: less than 5 inches (12 centimetres) from end to end. Researchers gave it a new species name, Masillastrix blattophaga.
What a shiny cockroach says about the clock
The insect inside the owl was greenish-blue and iridescent, meaning its colour shifts and shimmers as the light changes, the way a soap bubble does. Iridescence of this kind is associated with a daytime lifestyle, so the team read the meal as a sign that the owl was hunting while the sun was up.
Identifying the insect took some luck. A cockroach identical to the one in the stomach turned up in the sediments just a few feet away from the fossil, and that well-preserved specimen helped the researchers work out what the owl had eaten.
The team did allow for one uncertainty. It is possible the owl caught the cockroach at dawn or at dusk, which would leave open the question of whether it was truly a daytime hunter.
Why owls switched to the night shift
Gerald Mayr, a paleontologist and head of ornithology at the Senckenberg Research Institute and the Natural History Museum Frankfurt in Germany, is the first author of the study. He said there is broad agreement among researchers that owls must have evolved from an ancestor that was active by day.
Some early owl fossils support that idea. They have head-turning structures like those of birds of prey that hunt in daylight, and bony ridges above the eye sockets that could have shaded the eyes from the sun.
Mayr said it is plausible that the Messel owl was fully active in the daytime, rather than active both day and night as some owls are today. If it had been active around the clock, that would suggest some of its ancestors had already developed night-living traits, which does not fit the picture.
The study was published on 2 November in the journal Current Biology. The find does not settle the whole question of when owls became nocturnal, but it pushes the answer back: 47 million years ago, at least this small owl was a day hunter.