BETA SAÚDE
Epipterygoid
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The epipterygoid is a paired cranial bone present in many osteichthyans including tetrapods. It acts as a vertical strut connecting the pterygoid bone of the palate to the outer surface of the braincase or the underside of the skull roof. The epipterygoid is an endochondral bone, derived from the cartilage of the branchial arches.[1]
Evolution
The epipterygoid is part of the splanchnocranium, and as such it originated as a portion of the first gill arch in basal chordates. The epibranchial element of the first gill arch evolved into the palatoquadrate[2]; in osteichthyes, this element typically remains mostly cartilaginous. However, the anteriormost portion of the palatoquadrate does ossify, and becomes the epipterygoid.[1]
In squamates, the epipterygoid generally has a slender rod-like shape, and is also known as the columella cranii.[3] Though present in many extinct archosaurs, it has been independently lost in modern crocodilians and birds.[4][5]
The epipterygoid is considered to be homologous to the alisphenoid bone of mammals.[6]
References
- 1 2 Kardong, Kenneth (2015). Vertebrates: Comparative Anatomy, Function, Evolution -Seventh edition. New York: McGraw-Hill Education. pp. 244–248, 256. ISBN 978-0-07-802302-6.
- ↑ Gillis, J. Andrew; Modrell, Melinda S.; Baker, Clare V. H. (2013-02-05). "Developmental evidence for serial homology of the vertebrate jaw and gill arch skeleton". Nature Communications. 4 (1): 1436. doi:10.1038/ncomms2429. ISSN 2041-1723. PMC 3600657. PMID 23385581.
- ↑ Jollie, Malcolm T. (1960). "The head skeleton of the lizard". Acta Zoologica. 41 (1–2): 1–64. doi:10.1111/j.1463-6395.1960.tb00474.x. ISSN 1463-6395.
- ↑ Holliday, Casey M.; Witmer, Lawrence M. (2009-09-12). "The epipterygoid of crocodyliforms and its significance for the evolution of the orbitotemporal region of eusuchians". Journal of Vertebrate Paleontology. 29 (3): 715–733. doi:10.1671/039.029.0330. ISSN 0272-4634.
- ↑ Clark, James M.; Welman, Johann; Gauthier, Jacques A.; Parrish, J. Michael (1993-03-18). "The laterosphenoid bone of early archosauriforms". Journal of Vertebrate Paleontology. 13 (1): 48–57. doi:10.1080/02724634.1993.10011487. ISSN 0272-4634.
- ↑ Hopson, James A.; Rougier, Guillermo W. (1993-01-01). "Braincase structure in the oldest known skull of a therian mammal; implications for mammalian systematics and cranial evolution". American Journal of Science. 293 (A): 268–299. doi:10.2475/ajs.293.A.268. ISSN 0002-9599.
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