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Comparative morphology of the avian bony columella (1 Viewer)

Fred Ruhe

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John Peacock, Garth M. Spellman, Daniel J. Field,,Matthew J. Mason & Gerald Mayr, 2024.

Comparative morphology of the avian bony columella

Anatomical Record, 307: 1735–1763
doi: 10.1002/ar.25278

Abstract: Comparative morphology of the avian bony columella

In birds, the columella is the only bony element of the sound conducting apparatus, conveying vibrations of the cartilaginous extracolumella to the fluid of the inner ear. Although avian columellar morphology has attracted some attention over the past century, it nonetheless remains poorly described in the literature. The few existing studies mostly focus on morphological descriptions in relatively few taxa, with no taxonomically broad surveys yet published. Here we use observations of columellae from 401 extant bird species to provide a comprehensive survey of columellar morphology in a phylogenetic context. We describe the columellae of several taxa for the first time and identify derived morphologies characterizing higher-level clades based on current phylogenies. In particular, we identify a derived columellar morphology diagnosing a major subclade of Accipitridae. Within Suliformes, we find that Fregatidae, Sulidae, and Phalacrocoracidae share a derived morphology that is absent in Anhingidae, suggesting a secondary reversal. Phylogenetically informed comparisons allow recognition of instances of homoplasy, including the distinctive bulbous columellae in suboscine passerines and taxa belonging to Eucavitaves, and bulging footplates that appear to have evolved at least twice independently in Strigiformes. We consider phylogenetic and functional factors influencing avian columellar morphology, finding that aquatic birds possess small footplates relative to columellar length, possibly related to hearing function in aquatic habitats. By contrast, the functional significance of the distinctive bulbous basal ends of the columellae of certain arboreal landbird taxa remains elusive.


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A tympanic middle ear evolved multiple times among vertebrates as a means to compensate for the impedance mismatch between air and the fluid-filled inner ear (Clack, 2002; Lombard & Bolt, 1979; Tucker, 2017). In birds, this system consists of a tympanic membrane, a cartilaginous extracolumella, a bony columella, several ligaments, and one muscle (see Figure 1, Smith, 1904, and Pohlman, 1921, for further details).

FIGURE 1 A drawing of the avian middle ear modified from Pohlman (1921), and based on Gallus gallus.

FIGURE 2 Palaeognathae, Galloanserae, and Neoaves (excluding Phaethoquornithes and Telluraves): Drawings of the columella in 62
species to illustrate the diversity of forms. These are shown in different orientations so as to illustrate key features. Note that the color of the bones varies with the condition of the specimen and the conditions under which it was observed: no other meaning should be ascribed to these differences. Palaeognathae: 1. Struthio camelus, 2. Rhea americana, 3. Apteryx australis, 4. Crypturellus undulatus, 5. Eudromia elegans, 6. Casuarius casuarius, 7. Dromaius novaehollandiae, Galloanserae: Galliformes: 8. Megapodius freycinet, 9. Crossoptilon auritum, 10. Penelope purpurascens, 11. Acryllium vulturinum, 12. Pipile pipile, 13. Pavo cristatus, Anseriformes: 14. Chauna chavaria, 15. Anas platyrhynchos, 16. Mergellus albellus, 17. Anser rossii, 18. Cygnus olor, Steatornithiformes: 19. Steatornis caripensis, Podargiformes: 20.Podargus strigoides, Apodiformes: 21. Aeronautes saxatalis, 22. Apus apus, Caprimulgiformes: 23. Uropsalis segmentata, 24. Phalaenoptilus nuttallii, 25. Chordeiles minor, Musophagiformes: 26. Musophaga violacea, 27. Musophaga rossae, 28. Corythaixoides concolor, Cuculiformes: 29. Piaya melanogaster, 30. Chrysococcyx caprius, Otidiformes: 31. Otis tarda, 32. Ardeotis kori, Columbiformes: 33. Streptopelia decaocto, 34. Ducula bicolor, 35. Zenaida macroura, 36. Columba livia, 37. Geopelia striata, Pterocliformes: 38. Pterocles exustus, Gruiformes: 39. Rallus elegans, 40. Grus monacha, 41. Psophia leucoptera, 42. Aramus guarana, Phoenicopteriformes: 43. Phoenicopterus chilensis, 44. Phoenicopterus ruber, Podicipediformes: 45. Podilymbus podiceps, 46. Tachybaptus dominicus, Charadriiformes: 47. Burhinus bistriatus, 48. Vanellus armatus, 49. Haematopus ostralegus, 50. Recurvirostra americana, 51. Jacana jacana, 52. Limnodromus scolopaceus, 53. Numenius arquata, 54. Scolopax minor, 55. Limosa limosa, 56. Alca torda, 57. Fratercula arctica, 58. Anous stolidus, 59. Larosterna inca, 60. Larus hyperboreus, 61. Stercorarius pomarinus, Opisthocomiformes: 62. Opisthocomus hoazin.

FIGURE 3 A drawing of a columella with the major sections labeled.
FIGURE 4 The phylogeny of the Palaeognathae following Prum et al. (2015) and Kuhl et al. (2021), with columellar types of higher-level taxa shown. The columellae are from Struthio camelus (Struthionidae), Rhea americana (Rheidae), Apteryx australis (Apterygidae), Crypturellus undulatus and Eudromia elegans (Tinamidae), Casuarius casuarius and Dromaius novaehollandiae

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