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just inside the upper jaw. These internal nasal passages evolved while the vertebrates still lived in water. In animals with complete secondary palates (mammals, crocodilians, most skinks) the space between the primary and secondary palates contain the nasal passages, with the choanae located above the posterior end of the secondary palate.
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In all but the most basal (primitive) tetrapodomorphs (or "choanates"), the excurrent nostrils have migrated from the edge of the mouth to the interior of the mouth. In tetrapods that lack a secondary palate (basal tetrapods and amphibians), the choanae are located forward in the roof of the mouth,
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Early bony fishes (~420 mya) had two pair of nostrils, one pair for incoming water (known as the anterior or incurrent nostrils), and a second pair for outgoing water (the posterior or excurrent nostrils), with the olfactory apparatus (for sense of smell) in between. In the first
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do not have choanae, instead they have two pairs of external nostrils: each with two tubes whose frontal openings lie close to the upper jaw, and the posterior openings further behind near the eyes. A 395-million-year-old fossil lobe-finned fish called
287:(~415 mya) the excurrent nostrils migrated to the edge of the mouth, occupying a position between the maxillary and premaxillary bones, directly below the lateral rostral (a bone that vanished in early tetrapods).
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In animals with secondary palates, they allow breathing when the mouth is closed. In tetrapods without secondary palates their function relates primarily to olfaction (sense of smell).
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has something between a choana and the external nostrils seen on other fish. The posterior opening of the external nostrils has migrated into the mouth.
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separates the two halves of the posterior half of the palate, connecting the nasal cavity with the buccal cavity (mouth) and the pharynx (throat).
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shows an intermediate stage between posterior and interior nostril and supports the independent origin of internal nostrils in the lungfish.
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have open canals that leads water from their external nostrils into their mouths and through their gills.
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The choanae (internal nostrils) of a cat, indicated by the dashed lines and bounded by the
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Dissection of the muscles of the palate from behind. (Choanae visible at center top.)
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In animals with partial secondary palates (most birds and reptiles), the median
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have a single internal nostril that opens inside the mouth cavity, while
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are two openings found at the back of the nasal passage between the
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The term is a latinization from the Greek χοάνη, "choanē" meaning
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It is therefore not a structure but a space bounded as follows:
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In lungfish, the inner nostrils are regarded as an example of
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Each of two openings from the nasal cavity to the throat
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Gaining Ground: The Origin and
Evolution of Tetrapods
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189:). They are considered one of the most important
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472:Biology and Comparative Physiology of Birds
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181:, in humans and other mammals (as well as
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469:(22 October 2013). A. J. Marshall (ed.).
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203:The choanae are separated in two by the
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215:A choana is the opening between the
796:Pharyngeal opening of auditory tube
248:superiorly and posteriorly by the
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475:. Elsevier Science. p. 412.
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1:
438:. JHU Press. pp. 150–1.
407:(2004) "Wandering nostrils".
44:Lateral wall of nasal cavity.
278:Choanae in different animals
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432:Linzey, Donald W. (2012).
531:Anatomy of the human nose
167:posterior nasal apertures
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49:
37:
801:Salpingopharyngeal fold
256:medial pterygoid plates
688:Ethmoidal infundibulum
673:Sphenoethmoidal recess
327:. The fossil lungfish
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121:Anatomical terminology
806:Salpingopalatine fold
649:Inferior nasal concha
639:Superior nasal concha
261:medially by the Vomer
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634:Supreme nasal concha
145:(blue gray) and the
849:Otorhinolaryngology
644:Middle nasal concha
764:Sphenoidal sinuses
435:Vertebrate Biology
325:parallel evolution
151:
831:
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823:Pharyngeal recess
818:Pharyngeal tonsil
751:Paranasal sinuses
745:
744:
719:Vomeronasal organ
482:978-1-4832-6379-3
467:Farner, Donald S.
445:978-1-4214-0040-2
405:Janvier, Philippe
379:978-0-253-35675-8
254:laterally by the
171:internal nostrils
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16:(Redirected from
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737:Olfactory mucosa
698:Maxillary hiatus
693:Semilunar hiatus
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364:Clack, Jennifer
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729:Nasal mucosa
714:Nasal septum
656:Nasal meatus
623:Lateral wall
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589:Nasal cavity
557:Septal nasal
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486:. Retrieved
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449:. Retrieved
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383:. Retrieved
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296:choanal slit
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217:nasal cavity
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183:crocodilians
175:nasal cavity
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90:A02.1.00.096
77:
707:Medial wall
577:Vomeronasal
545:Ala of nose
221:nasopharynx
67:Identifiers
838:Categories
683:Agger nasi
658:: (Supreme
572:Minor alar
567:Major alar
347:References
330:Diabolepis
314:Kenichthys
235:inferiorly
231:anteriorly
211:Boundaries
667:inferior)
341:chimaeras
337:Hagfishes
318:campbelli
266:Etymology
185:and most
661:superior
597:Openings
488:8 August
451:8 August
385:5 August
366:(2012).
219:and the
177:and the
149:(orange)
788:pharynx
609:Nostril
237:by the
179:pharynx
155:choanae
62:Details
664:middle
614:Choana
479:
442:
409:Nature
376:
272:funnel
187:skinks
163:choana
78:choana
33:Choana
844:Skull
306:Most
205:vomer
143:vomer
125:[
114:76585
73:Latin
784:Naso
490:2015
477:ISBN
453:2015
440:ISBN
387:2015
374:ISBN
308:fish
302:Fish
233:and
153:The
85:TA98
417:doi
413:432
241:of
193:of
169:or
165:),
159:sg.
109:FMA
102:501
97:TA2
840::
632::
411:,
395:^
355:^
274:.
223:.
207:.
161::
786:-
523:e
516:t
509:v
492:.
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419::
389:.
258:.
245:,
157:(
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20:)
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
