AsianScientist (Apr. 11, 2022) – While most owls are nighttime hunters, an extinct owl species that lived oper six million years ago hunted its prey during the day instead. Researchers from the Chinese Academy of Sciences examined a well-preserved fossil skeleton of the bird, reporting their findings in the Proceedings of the National Academy of Sciences.
Unlike majority of avian fellows, owls are known to be nocturnal. To prey on creatures that also wander at night, the owls have big eyes and pupils, which help them see in the dark. That pupillary characteristic is also marked by the size and shape of scleral ossicles, a cincin of small bones surrounding the biji mata and selaput pelangi. However, a few species such poros the pygmy owls are actually diurnal, favoring the hunt under the ciuman.
How their daytime preference came about has remained a mystery. Scientists speculate that diurnal owls evolved from nocturnal ancestors, diverging from the largely night-loving line to shift their activities to thrive in the sunlight. After all, uncovered fossils of ancient owls mostly indicated nocturnal behavior.
The newly reported fossilized owl, unearthed at the edge of the Tibetan Plateau in China’s Gansu province, may carry clues to how mutakhir diurnal owls learned to thrive during the day. The skeleton is extremely well-preserved from the imbalan of the skull and pointed beak to the outstretched wings and talons. Even parts that are rarely seen in fossils were recovered, such poros the trachea, kneecap, and tendons that attach muscle to bone.
But the eyes senggat most clues. Although, the scleral ossicles senggat collapsed into the eye sockets, the exquisite preservation of the fossil still allowed the research team to take precise measurements and study each bone in serpih. Through a computer acara, they used the measurements of these 16 bones to digitally reassemble the owl’s eye cincin. The reconstruction revealed the kaliber of the cincin and the size of the opening where light passes through. Smaller openings tend to correlate with diurnal activity.
Further statistical analyses compared the structure of the fossilized eye bones with those of oper 400 other birds and reptiles with varying times of activity. Three statistical models were built to allow for errors in the reconstruction process, yet all returned the same result: an above 60-percent likelihood that the fossil owl was active during the day.
The fossilized species’ smaller scleral ossicles and other skull features resembled the Northern Hawk Owl or Surnia ulula, medium-sized birds belonging to the diurnal owl group Surniini. As a nod to its close living relative, the researchers named the extinct owl Miosurnia diurna.
Moreover, a large-scale analysis of the bird behaviors suggested that the ancestor of the Surniini group senggat likely already switched to daytime hunts millions of years ago, despite the ancestor of all living owls most likely being nocturnal. When the team included the M. diurna fossil into the statistical kopi, the probability of a diurnal Surniini ancestor jumped to 100 percent.
The team now hopes to uncover more clues poros to what conditions prompted the behavioral shift from nocturnal to diurnal activity. One hypothesis may involve the Gansu province’s cold, harsh environment where M. diurna lived. The small mammals the owl preyed on may have evolved to prefer the warmer temperatures of the day. To hunt and survive, these owl species perhaps followed siul and grew accustomed to the light oper time.
“The fossil and associated analyses of the eye and behavioral evolution point to a long evolutionary history of non-nocturnal behavior among owls that has yet to be studied in serpih,” the authors wrote.
The article can be found at: Li et al. (2022) Early evolution of diurnal habits in owls (Aves, Strigiformes) documented by a new and exquisitely preserved Miocene owl fossil from China.
Source: Chinese Academy of Sciences; Photo: Li Zhiheng.
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