47-Million-Year-Old Owl Fossil Points to Daytime Hunting

Dr. Sonja Wedmann, head of the Messel excavation at the Senckenberg Research Institute and Natural History Museum in Frankfurt, examined the stomach remains. The wing remnant had strong longitudinal veins, which run along its length, and numerous transverse veins, which run across it. Those features identify it as a fossil cockroach.

Excavators found a similar, much better-preserved cockroach only a few metres from the owl, confirming that the material in the owl’s stomach came from a cockroach wing.

Living cockroaches and other insects with iridescent wings tend to be active during the day. That association makes the meal relevant to the predator’s own behavior.

Dr. Gerald Mayr of the Senckenberg Research Institute and Natural History Museum in Frankfurt explained: “Therefore, the cockroach found in the little owl’s stomach provides an important clue about the bird’s own period of activity.”

The fossil adds two anatomical checks:

• Flight feathers: The bird’s flight feathers lack the features typical of today’s nocturnal owls.
• Wing bone: Its humerus, or upper wing bone, is proportionately more abbreviated than in modern owls. Researchers read that shape as evidence that the bird’s wings were neither as long nor as well adapted for silent flight as those of present-day night hunters.

Takeaway: A daytime-active cockroach, daytime-type feathers and a less specialized silent-flight wing all point the same way, although none alone settles the question.

When did owls become nocturnal?

Although scientists have found many owl fossils, most preserve only a few isolated bones. Such fragments rarely reveal the full proportions of the wing. Here, diurnal means active during the day; nocturnal means active at night.

Mayr said: “It is still unknown when, in the evolutionary history of owls, the transition from a diurnal to a nocturnal lifestyle took place.”

The Messel humerus nevertheless provides a useful boundary. The oldest known owl with humerus proportions typical of modern owls lived in France about 35 million years ago. Because the 47-million-year-old Messel bird had the earlier proportions, the team proposes that nocturnal behavior emerged between the middle and late Eocene, about 47 to 34 million years ago.

The finding narrows the window but does not identify the first nocturnal owl or the exact moment of change. It rests on anatomical comparisons and the habits of living insects, not a continuous series of fossils showing the transition. The daytime meal therefore supplies a clue, not a direct timestamp for the evolution of nocturnality.

Takeaway: The authors’ estimate places the emergence of modern-style nighttime hunting between 47 and 34 million years ago.

What does the discovery make possible?

Wedmann said the specimen demonstrates what makes Messel exceptional: its preservation has kept fine details, including feathers and stomach contents, for more than 47 million years. Those details can show not only what the owl looked like but also how it lived, helping narrow the period when owls developed nocturnality.

The study, “Evidence for diurnal habits in an exceptionally preserved Eocene owl,” by Gerald Mayr and colleagues appeared in Current Biology in 2026. Its DOI is 10.1016/j.cub.2026.09.079.

Takeaway: The 47-million-year-old specimen anchors one end of the proposed transition: this owl hunted by day and retained earlier wing proportions than modern nocturnal owls.