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A nearly complete fossil owl found in Germany — with its last meal still intact — gives scientists new evidence about when owls began hunting at night. The specimen narrows the transition to a nocturnal lifestyle to a window between roughly **47 million** and **35 million** years ago, researchers say.
A fossil that preserves a final snack
Unearthed in 2025 at the Messel Pit, a world-renowned Eocene fossil site, the tiny bird has been described as a new species, Masillastrix blattophaga. Except for a missing skull, the specimen is remarkably complete. Inside its body cavity scientists found a greenish-blue, iridescent cockroach — interpreted as the owl’s last meal.
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The insect’s shimmering coloration matters because iridescence in insects is typically linked with daytime activity. That detail, along with other features of the skeleton and feathers, led the research team to propose that this juvenile owl hunted in daylight rather than at night.
Multiple lines of evidence for daytime habits
Lead author Gerald Mayr, a paleontologist at the Senckenberg Research Institute and the Natural History Museum Frankfurt, and colleagues argue the fossil carries several markers consistent with a **diurnal** lifestyle.
- The preserved cockroach shows iridescence, a trait associated with insects that are active during the day.
- Researchers found the same cockroach species in the sediment near the fossil, strengthening the identification of the stomach contents.
- The bird’s upper wing bones — or humeri — are relatively robust, a shape the team links to owls that fly by sight rather than relying on silent flight.
Mayr and the co-authors note that while the owl could have eaten the insect at dawn or dusk, the combination of skeletal and soft-tissue clues makes a daytime hunting pattern more likely.
Placing the switch to night hunting on a timeline
If the Messel bird was primarily diurnal 47 million years ago, then the emergence of truly nocturnal owls would have occurred later. The study points to the Late Eocene, around **35 million years ago**, as the earliest clear evidence of owls with anatomy resembling modern night hunters.
The fossil record still has gaps. Many early owl species are known from fragmentary remains, so pinning down exact timing is difficult. But the new specimen helps narrow the window: owls probably shifted from day-active ancestors to mostly nocturnal forms sometime between about 47 and 35 million years ago.
Why the change remains unexplained
Previous hypotheses suggested owls went nocturnal to avoid competition with diurnal raptors or to exploit a rising diversity of nocturnal mammals. However, the fossil and molecular evidence cited by the authors indicate those other groups did not dramatically expand until roughly 20–25 million years ago — well after the proposed 35-million-year mark.
That temporal mismatch deepens the mystery. “Narrowing down the time frame when owls became nocturnal may eventually contribute to solving this mystery,” the researchers write, emphasizing that more fossils will be needed to test competing explanations.
What this fossil adds to avian history
The Messel discovery also reinforces how little is settled about early modern-bird evolution. The oldest described owl in the record, Ogygoptynx wetmorei, dates to roughly 60 million years ago, but it, and other early forms, do not show the full suite of nocturnal adaptations seen in living owls.
The new study, published Nov. 2 in Current Biology, therefore shifts an important question from vague deep time into a narrower interval that future finds can investigate. Each well-preserved fossil from sites like Messel can change our understanding of when and why major behavioral shifts evolved in birds.
