Fossilised remains of an owl that lived 47 million years ago in what is now Germany suggest that early owls were active during the day, helping to narrow the period when the birds evolved nocturnal habits. The newly described species, Masillastrix blattophaga, was unearthed in the Messel Pit, a renowned Eocene fossil site, and is so well preserved that researchers found a cockroach in its stomach, likely its last meal.
Study first author paleontologist Gerald Mayr of the Senckenberg Research Institute and Natural History Museum Frankfurt in Germany examined the almost perfectly preserved fossil, whose skull is missing. The presence of a greenish-blue, iridescent cockroach in the bird's stomach is one of several clues pointing to a diurnal lifestyle. Iridescence is associated with daytime activity, and the shape of the owl's upper wing bones also suggests it flew during the day, when silent flight is less advantageous.
“There exists a consensus that owls must have evolved from a diurnal ancestor,” Mayr said in an email to Live Science. He noted that some earlier owl fossils have features similar to those of diurnal raptors. Mayr said it was plausible that the Messel owl was fully diurnal, rather than active at both day and night, because the latter would imply that some ancestors had already evolved nocturnal traits.
Assuming this hypothesis is correct, the earliest known nocturnal owl species date to around 35 million years ago, in the Late Eocene, Mayr said, and have wing bones resembling those of modern owls. Owls likely became nocturnal between 47 million and 35 million years ago. The oldest owl fossil, Ogygoptynx wetmorei, dates to about 60 million years ago.
Mayr said the study, published Nov. 2 in Current Biology, helps refine the timeline but also deepens the mystery of why owls turned nocturnal. Previous theories pointed to competition with diurnal birds of prey or the proliferation of nocturnal mammals, but both groups exploded much later, around 20 million to 25 million years ago. "by narrowing down the time frame when owls became nocturnal, our study may eventually contribute to solving this mystery," Mayr said.
He added that little is known about the early evolution of modern birds, and every fossil discovery has the power to change even well-established ideas.
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millions of years ago
The owl's shift to nocturnal habits occurred between the 47-million-year-old Messel owl and the earliest known nocturnal owls, about 35 million years ago. Source: Mayr et al., Current Biology; reported by Live Science
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Analysis
Why This Matters
The discovery provides the earliest direct evidence of diurnal behavior in owls, refining the timeline for when they evolved nocturnal habits.
The exceptional preservation offers a rare window into the life of an ancient bird.
Narrowing the nocturnal transition to a 12-million-year window helps future research focus on the environmental drivers of the shift.
Background
The Messel Pit in Germany is a rich fossil site from the Eocene epoch, known for exceptionally preserved specimens. The owl fossil record is sparse, and previous studies had suggested a diurnal ancestor based on skull features, but direct evidence has been lacking.
What to Watch
Future discoveries in the 47-to-35-million-year window may pinpoint a more precise date for the nocturnal shift.
Studies of ecological pressures in the Late Eocene could reveal why nocturnality became advantageous.
Analysis of other early owl fossils for similar preservation clues could confirm whether the findings apply broadly.
12 claims in this story checked against 1 source: 11 supported.
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Partly supportedThe owl’s remains were perfectly preserved.Latest from Live Science: “The discovery brings researchers one step closer to finally solving the biggest mystery about these birds. The young owl is a newly described species named Masillastrix blattophaga. Researchers unearthed the almost perfectly preserved bird”
SupportedA 47-million-year-old owl fossil suggests owls were active during the day and helps narrow when they became nocturnal.Latest from Live Science: “A fledgling owl that lived 47 million years ago in what is now Germany offers tantalizing new clues about when most of these birds became nocturnal, a new study shows.”
SupportedThe fledgling owl’s stomach contained a cockroach described as its likely last meal.Latest from Live Science: “The skull is missing, but the rest of the fossil was so well preserved that researchers found the owl's last meal in its stomach: a greenish-blue, iridescent cockroach.”
SupportedMayr said, “There exists a consensus that owls must have evolved from a diurnal ancestor,” in an email to Live Science.Latest from Live Science: “"There exists a consensus that owls must have evolved from a diurnal ancestor," Mayr told Live Science in an email.”
SupportedThe cockroach’s iridescence and the owl’s upper wing bones are clues that it was diurnal.Latest from Live Science: “But there are other clues hinting that the owl was diurnal, including the appearance of some of the owl's feathers and the stoutness of its upper wing bones.”
SupportedMayr said some earlier owl fossils have features similar to those of diurnal raptors.Latest from Live Science: “That's because some early owl fossils have head-rotation structures similar to those of diurnal raptors and bony ridges above the eye sockets that could have shaded the owls' eyes from the sun.”
SupportedThe earliest known nocturnal owl species date to around 35 million years ago, assuming the hypothesis is correct.Latest from Live Science: “Assuming this hypothesis is correct, the earliest known nocturnal owl species are from about 35 million years ago, in the Late Eocene, Mayr said.”
SupportedThe oldest known owl fossil, Ogygoptynx wetmorei, dates to about 60 million years ago.Latest from Live Science: “The oldest known owl in the fossil record, Ogygoptynx wetmorei, dates to around 60 million years ago.”
SupportedThe study was published Nov. 2 in Current Biology.Latest from Live Science: “the researchers wrote in the study, which was published Nov. 2 in the journal Current Biology.”
SupportedEarlier theories suggested competition with diurnal birds of prey or the proliferation of nocturnal mammals, but both groups expanded around 20 million to 25 million years ago.Latest from Live Science: “Previous theories suggested that owls evolved this behavior to avoid competition with diurnal birds of prey or to benefit from a proliferation of nocturnal mammals. But studies show that both of these groups exploded much later than 35 million years ago — around 20 million to 25 million years ago”
SupportedMayr said, “by narrowing down the time frame when owls became nocturnal, our study may eventually contribute to solving this mystery.”Latest from Live Science: “But "by narrowing down the time frame when owls became nocturnal, our study may eventually contribute to solving this mystery," Mayr said.”
SupportedMayr said little is known about the early evolution of modern birds and that every fossil discovery can change established ideas.Latest from Live Science: “"We still know so little about the early evolution of modern birds," Mayr said, adding that every fossil discovery has the power to change even well-established ideas in the field.”
