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Miosurnia diurna gen. nov. sp. nov. (1 Viewer)

Fred Ruhe

Well-known member
Zhiheng Li, Thomas A. Stidham, Xiaoting Zheng, Yan Wang, Tao Zhao, Tao Deng & Zhonghe Zhou, 2022

Early evolution of diurnal habits in owls (Aves, Strigiformes) documented by a new and exquisitely preserved Miocene owl fossil from China

Proceedings of the National Academy of Sciences of the United States of America. 119 (15): e2119217119. doi:10.1073/pnas.2119217119

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: https://www.pnas.org/doi/abs/10.1073/pnas.2119217119
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.

Miosurnia diurna gen. nov. sp. nov. is described


Systematic Paleontology

Aves Linnaeus, 1758
Strigiformes Wagler, 1830
Strigidae Leach, 1820
Surniini Weick, 2006 (33)
Miosurnia diurna gen. et sp. nov. Li, Stidham, and Zhou, 2022.

Holotype. The holotype is Shandong Tianyu Museum of Nature STM 20-1 (Linyi, Shandong Province, China), a nearly complete articulated bird skeleton, lacking the right forelimb and left manual digits.

Genus and Species Diagnosis. The taxon is a medium-sized owl with a body length of ∼30 cm (estimated from rostrum to pubis; Fig. 1) with an estimated body mass of ∼236 to 319 g (34, 35), roughly the same as S. ulula and much larger than
Glaucidium (25). The holotype specimen can be referred to Strigidae using numerous derived features including the presence of an ossified extensorial arcus (retinaculum extensorii) on the proximodorsal surface of the tarsometatarsus (Fig. 1), and M. diurna differs from Tytonidae (barn owls) in having a much shorter skull rostrum (∼1/3 of skull length; SI Appendix, Table S1) and a sternum bearing two notches caudally (Fig. 1). M. diurna lacks the irregular projection of the ventrocaudal
edge of the naris that is present in strigine genera (Strix, Asio, and others) and differs from species of Striginae in the following combination of characters: the mandible bears a short retroarticular process, and the caudal portion of jugal bar bears an enlarged dorsal projection (present in Surnia, Glaucidium, and Ninox); the projection is rudimentary in Athene and also variable in size within other Surniini taxa (36). The holotype lacks the extremely long and slender zygomatic process present in species of Asioninae.
M. diurna shares most of its features with taxa within the strigid clade Surniini (i.e., Surnia and Glaucidium) including a straight minor metacarpal, a short and stocky tarsometatarsus, and particularly an enlarged dorsal projection caudal to the orbit
on the caudodorsal portion of jugal bar (SI Appendix, Fig. S1). The holotype has a shallower dorsal concave surface of metatarsal trochlea III than that present in Surnia. The zygomatic process of the squamosal is pointed and slightly longer than that of Surnia and Glaucidium (SI Appendix, Fig. S1). This taxon differs from species of Glaucidium in its larger size, proportionally longer rostrum, absence of a bulge on the frontals along the nasalfrontal hinge, and a smaller process on the caudal portion of the jugal bar (37). S. robusta is larger and more robust compared with M. diurna (26), and metatarsal trochlea IV is positioned more proximal than the state in the holotype. The humerus of S. robusta is longer than M. diurna with a less projected deltopectoral crest, and the tarsometatarsus of M. diurna has a less projected lateral crest adjacent to the cotyle. According to descriptions of the Pleistocene fossil species S. capeki (27), the proximal width is greater than in the extant Surnia and M. diurna. The characters shared between Miosurnia and S. ulula
include a wing-shaped squamosal expansion, six sternal ribs and costal processes, and a knob-like structure projecting ventrally from the minor metacarpal (SI Appendix, Fig. S1).
M. diurna exhibits two potential autapomorphies. The most caudal free sternal rib (possibly the sixth) has an unusual hammer-shaped outline for articulation with the thoracic rib (SI Appendix, Fig. S2), and this morphology is unknown among other species of Strigidae including Surnia and Glaucidium. The radius of the holotype also lacks the ossified arch that fuses to the proximal end present in most owls (38).

Age and Horizon. The M. diurna holotype is from the Liushu Formation exposed in the Linxia Basin of Gansu Province, adjacent to the northeastern edge of Tibetan Plateau in China (SI Appendix, Fig. S3). The age of the fossil-bearing sediments of the Liushu Formation is 6.0 to 9.5 Ma (39) and roughly equivalent to the European Land Mammal Ages MN 9 to 13 (40).

Etymology. The genus name is in reference to its Miocene age and similarity in morphology with the extant owl Surnia, and the specific epithet refers to the evidence for this owl as an active diurnal bird.


Fig. 1. Photograph and line drawing of the complete holotype specimen of M. diurna (STM 20-1). Anatomical abbreviations: al, alular digit; b, bony residue; c, ceratobranchial; cr, cranial process of sternum; dc, deltopectoral crest; ep, extensor process; er, ossified extensor rectinaculum; ex, extensor sulcus; fe, femur; fi, fibula; fm, foramen magnum; hu, humerus; hy, hypotarsal crest; im, intermetacarpal space; is, ischium; lc, lateral condyle; lt, left tibiotarsus; mc, medial condyle; mm, major metacarpal; mp, manual phalanx; ms, mandibular symphysis; mtII, trochlea of metatarsal II; p, patella; pd, pedal digits; pg, paraglossum; qu, quadrate; ra, radius; rad, radiale; ri, rib; rs, rostrum; rt, right tibiotarsus; sc, scapula; sk, skull; so, scleral ossicle; st, sternum; sy, synsacrum; tm, tarsometatarsus; tr, tracheal ring; ul, ulna; and uln, ulnare.


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Laurent Raty wrote:

"Are works issued in this journal and not registered in ZooBank published in the sense of the Code ?

“As of 2015 the journal stopped advertising a print option to subscribers.” – https://doi.org/10.1073/pnas.1602165113
"PNAS will cease producing the print edition as of 1/19." – "

I would not know, my health doesn't allow me to visit a library often, I mainly work from house and on line.

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