Owls 6 million years ago didn’t work the night shift?

◎ Science and Technology Daily reporter Lu Chengkuan

There is a folk saying: Owls are happy at night. In everyone's impression, owls are birds that hide during the day and come out at night. They are all night owls, active at night and disappear during the day.

So, is there a type of owl that doesn't work the night shift and is active during the day?

Really! Researchers from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, discovered fossils of a diurnal owl on the edge of the Qinghai-Tibet Plateau. This extinct ancient species was active during the day and lived in the late Miocene epoch, about 6 million to 9.5 million years ago. The relevant research results were published online in the Proceedings of the National Academy of Sciences.

"This is the earliest Strigiformes bird fossil discovered in our country. Fortunately, its remains have been preserved basically intact." On March 29, Li Zhiheng, an associate researcher at the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, said in an interview with Science and Technology Daily.

Owls are a general term for birds in the order Strigiformes. The vast majority of modern owls are indeed silent nocturnal birds of prey. However, most people may not know that a few owls are more adapted to daytime hunting and are more active during the day.

"Due to the lack of fossil evidence, the evolutionary history of this type of owl that is active during the day has been largely hidden and rarely studied by scientific researchers." Li Zhiheng introduced that this nearly complete fossil was found in the Willow Formation in the Linxia Basin in Gansu Province, and its body shape is closer to that of the northern eagle owl.

The researchers conducted a detailed statistical analysis and comparison of the scleral bones of the newly discovered owl fossils with the scleral bones and eye socket sizes of 55 species of reptiles and more than 360 species of birds, including many species of owls.

"We found that the eyes of this extinct owl were less open to light, which greatly reduced the amount of sunlight penetrating into the eyes, allowing it to see clearly at noon," said Li Zhiheng.

A photo of the holotype of the new owl and a focus on the eye bones. (The blue overlay is the sclera bone, and the right side shows the complete sclera ring in the eye socket of a modern owl)

Image source: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences

At the same time, the researchers also conducted a larger statistical analysis based on data from more than 360 species in the Bird Diversity Database.

The results showed that the ancestors of existing owls were almost all nocturnal and their activity patterns were mainly at night; but the ancestors of the genus pygmy owl, including the genus Owl and the Sino-Singapore pygmy owl, were "daywalkers" and were more active during the day.

The researchers found undigested food boluses in the specimen's stomach. Analysis showed it contained small mammal bones similar to those found in the kestrel's stomach. The researchers believe the two birds may have coexisted on the dry grasslands of the Qinghai-Tibet Plateau, but "may have used different foraging methods."

Because the new specimen has a large lump-shaped protrusion at the tail of the zygomatic bone behind the eye, the researchers classified it as a sister group of owls consisting of northern eagle owls and owls. "Taking into account its living era, living habits, bone characteristics, etc., we named this species Diurnal Neoraptor, which means a raptor of the order Strigiformes from the Miocene," said Li Zhiheng.

He said that the diurnal Sino-Michigan Sharp Owl is the first well-preserved fossil of a Miocene owl found in China. This study not only helps us reconstruct the evolutionary history of owls' diurnal-nocturnal behavior, but also provides new evidence for the study of the paleoecology around the Qinghai-Tibet Plateau in the late Miocene and the evolution of the Palearctic birds.

Source: Science and Technology Daily

Editor: Liu Yiyang

Review: Yue Liang

Final judge: He Yi