Researchers have discovered the spectacularly preserved remains of an owl in the Linxia Basin in Gansu province, up in the high-elevation Liushu Formation close to the northeastern edge of the Tibetan Plateau, that lived between 6 to 10 mya (Late Miocene), which unlike most other owls, was diurnal (which is to say, active chiefly during daylight hours). In fact, this specimen preserves the oldest evidence for daytime behavior in owls.
The bird measured at about 30cm (12") from rostrum to pubis, and a likely body mass of between 236 and 318 gms (0.520–0.701 lb.). The remains themselves preserved nearly the entire skeleton from its head to feet, including the tail bone. Basically, this nearly complete articulated bird skeleton lacks only the right forelimb and left manual digits.
The team named the owl Miosuria diurna with the first or genus name being in reference to the Miocene age of the specimen combined with the extant genus of owl, Surnia, with which it shares many morphological features. The second or species name refers to the evidence that this owl was an active diurnal bird.
The researchers said that they examined Miosuria's eye bones and then compared their characteristics with those of some 360 species of bird and 55 species of reptile, leading them to conclude that the owl was diunal. Further analysis of the remains revealed that Miosuria had descended from fully nocturnal owls.
Li Zhiheng, the lead author of the study and a researcher with the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology, said the discovery represents the first trace of an ancient daytime-active owl and that the evolution of diurnal owls might be linked to changes in the climate and environment in the Tibetan Plateau, but more research is needed to confirm this.
The abstract from the paper, Early evolution of diurnal habits in owls (Aves, Strigiformes) documented by a new and exquisitely preserved Miocene owl fossil from China can be read below:
The bird measured at about 30cm (12") from rostrum to pubis, and a likely body mass of between 236 and 318 gms (0.520–0.701 lb.). The remains themselves preserved nearly the entire skeleton from its head to feet, including the tail bone. Basically, this nearly complete articulated bird skeleton lacks only the right forelimb and left manual digits.
The team named the owl Miosuria diurna with the first or genus name being in reference to the Miocene age of the specimen combined with the extant genus of owl, Surnia, with which it shares many morphological features. The second or species name refers to the evidence that this owl was an active diurnal bird.
The researchers said that they examined Miosuria's eye bones and then compared their characteristics with those of some 360 species of bird and 55 species of reptile, leading them to conclude that the owl was diunal. Further analysis of the remains revealed that Miosuria had descended from fully nocturnal owls.
Li Zhiheng, the lead author of the study and a researcher with the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology, said the discovery represents the first trace of an ancient daytime-active owl and that the evolution of diurnal owls might be linked to changes in the climate and environment in the Tibetan Plateau, but more research is needed to confirm this.
The abstract from the paper, Early evolution of diurnal habits in owls (Aves, Strigiformes) documented by a new and exquisitely preserved Miocene owl fossil from China can be read below:
Significance
Owls, with their largely nocturnal habits, contrast strikingly with the vast majority of diurnal birds. A new spectacular late Miocene owl skeleton from China unexpectedly preserves the oldest evidence for daytime behavior in owls. The extinct owl is a member of the clade Surniini, which contains most living diurnal owl species. Analysis of the preserved eye bones documents them as consistent with diurnal birds, and phylogenetically constrained character mapping coincides with a reconstruction of an early evolutionary reversal away from nocturnal habits in this owl group. These results support a potential Miocene origin of nonnocturnal habits in a globally distributed owl group, which may be linked to steppe habitat expansion and climatic cooling in the late Miocene.
Abstract
Nocturnal owls exhibit adaptations thought to be evolutionarily associated with their diets, morphologies (sensory and flight), and diel activity patterns. However, that evolutionary history is not so simple, as demonstrated by an exquisitely preserved partial skeleton of an owl from the late Miocene of China that represents the first fossil evidence for diurnal behavior among owls. The fossil from the high-elevation Liushu Formation preserves most of the skeleton including the scleral ossicles. Osteological features place the holotype specimen as a member of the strigid clade Surniini. In contrast to the largely nocturnal owls, nonnocturnal (diurnal and crepuscular) species are concentrated within the Surniini as a likely evolutionary reversal in diel activity patterns. Analyses of the preserved scleral ossicles in the fossil demonstrate that it exhibits a large exterior scleral ossicle ring diameter with a large orbital length, supporting the hypothesis that this extinct owl was largely diurnal in its habits. Furthermore, stochastic character mapping, combined with Bayesian ancestral state reconstruction of the activity patterns of extant birds, demonstrates higher posterior probabilities of diurnal behavior among early diverging Surniini, and the addition of this extinct taxon into analyses enhances the hypothesis of this clade’s diurnal origin. The fossil and associated analyses of the eye and behavioral evolution point to a long evolutionary history of nonnocturnal behavior among owls that has yet to be studied in detail. This diurnal owl joins a growing Liushu avifauna that would have hunted small mammals in the savanna-like habitats adjacent to the rising Tibetan Plateau.
Owls, with their largely nocturnal habits, contrast strikingly with the vast majority of diurnal birds. A new spectacular late Miocene owl skeleton from China unexpectedly preserves the oldest evidence for daytime behavior in owls. The extinct owl is a member of the clade Surniini, which contains most living diurnal owl species. Analysis of the preserved eye bones documents them as consistent with diurnal birds, and phylogenetically constrained character mapping coincides with a reconstruction of an early evolutionary reversal away from nocturnal habits in this owl group. These results support a potential Miocene origin of nonnocturnal habits in a globally distributed owl group, which may be linked to steppe habitat expansion and climatic cooling in the late Miocene.
Abstract
Nocturnal owls exhibit adaptations thought to be evolutionarily associated with their diets, morphologies (sensory and flight), and diel activity patterns. However, that evolutionary history is not so simple, as demonstrated by an exquisitely preserved partial skeleton of an owl from the late Miocene of China that represents the first fossil evidence for diurnal behavior among owls. The fossil from the high-elevation Liushu Formation preserves most of the skeleton including the scleral ossicles. Osteological features place the holotype specimen as a member of the strigid clade Surniini. In contrast to the largely nocturnal owls, nonnocturnal (diurnal and crepuscular) species are concentrated within the Surniini as a likely evolutionary reversal in diel activity patterns. Analyses of the preserved scleral ossicles in the fossil demonstrate that it exhibits a large exterior scleral ossicle ring diameter with a large orbital length, supporting the hypothesis that this extinct owl was largely diurnal in its habits. Furthermore, stochastic character mapping, combined with Bayesian ancestral state reconstruction of the activity patterns of extant birds, demonstrates higher posterior probabilities of diurnal behavior among early diverging Surniini, and the addition of this extinct taxon into analyses enhances the hypothesis of this clade’s diurnal origin. The fossil and associated analyses of the eye and behavioral evolution point to a long evolutionary history of nonnocturnal behavior among owls that has yet to be studied in detail. This diurnal owl joins a growing Liushu avifauna that would have hunted small mammals in the savanna-like habitats adjacent to the rising Tibetan Plateau.
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