// Workers AI · dad joke modeWhat did epiotic say? "I'm epic, no tic.
In vertebrates, the epiotic is a skull bone that participates in the otic capsule and sometimes the external skull wall[1]; along with the prootic and the opisthotic, it encloses the inner ear. Because it frequently fuses to other elements early in ontogeny, it is poorly understood.[2]
Evolution
[edit]The epiotic is present as a distinct element in many actinopterygian fishes[3], though its homology is debated (see below).
It is absent in most turtles.[4] In at least snakes[5][6] and other squamates[7] and pseudosuchians,[8][9] it is present and fused to the supraoccipital, as in the turtle Phrynops[4] and some dinosaurs[10]; in juveniles of some ornithischians, the element is distinct.[11] In birds the element commonly forms a part of the external cranial surface.[1] In mammals and other synapsids, it is believed to be fused to the prootic and the opisthotic to form the petrosal; as the petrosal in humans is fused with the squamosal and tympanic to form the temporal bone, the epiotic may form part of the petrous part of the temporal bone.[2]
History of study
[edit]In 1670, Dutch anatomist Theodor Kerckring noted the presence of three distinct ossification centers in the human otic capsule. The significance of this, however, was not recognised at the time.[12]
In his 1858 Croonian Lecture, Thomas Henry Huxley proposed that the otic region of the ostrich consisted of three bones - an anterior, which he called the petrosal, a posterior, which he called the mastoid, and a third. This third bone he termed the epiotic. He further argued that in birds and snakes the element fuses to the supraoccipital, but remained distinct in fishes.[13] By 1864, however, he had changed his opinion, now believing that the so-called "mastoid" developed from portions of all three bones, and identified the remaining two as the prootic and opisthotic.[12] This sparked a decades-long debate over the presence of the epiotic in mammals, and of the homology of the petrosal in general, with authors such as Georg Baur arguing that the epiotic was entirely absent in reptiles..[2] Lyell Thomas in 1926 found evidence of three ossification centres in embryonic mice, which he took to support Huxley's interpretation.[2]
Due to its extreme degree of fusion, it is difficult to isolate and is poorly studied.[2] Additionally, its homology is debated. For example, in actinopterygiian fishes, where an element that is commonly referred to as the "epiotic" exists as a distinct bone, there has been a long history of confusion with the pterotic and the epioccipital, with authors such as Colin Patterson expressing doubt over whether the element is a true epiotic.[14][15]
References
[edit]- 1 2 Lyons, Sebastián; Rosset, Sergio D.; Picasso, Mariana; Hospitaleche, Carolina Acosta (2026-01-20). "Functional and evolutionary insights from postnatal skull and cervical development in woodpeckers (Aves: Picinae)". Vertebrate Zoology. 76: 33–49. doi:10.3897/vz.76.e173317. ISSN 2625-8498.
- 1 2 3 4 5 Thomas, Lyell J. (1926). "Ossification centers in the petrosal bone of the mouse". The Anatomical Record. 33 (2): 59–68. doi:10.1002/ar.1090330202. ISSN 1097-0185.
- ↑ Jollie, Malcolm (Feb 1986). "A primer of bone names for the understanding of the actinopterygian head and pectoral girdle skeletons". Canadian Journal of Zoology. 64 (2): 365–379. Bibcode:1986CaJZ...64..365J. doi:10.1139/z86-058. ISSN 0008-4301.
- 1 2 Bona, Paula; Alcalde, Leandro (Oct 2009). "Chondrocranium and skeletal development of Phrynops hilarii (Pleurodira: Chelidae)". Acta Zoologica. 90 (4): 301–325. doi:10.1111/j.1463-6395.2008.00356.x. hdl:11336/25603. ISSN 0001-7272.
- ↑ Khannoon, Eraqi R.; Evans, Susan E. (2015-04-10). "The Development of the Skull of the Egyptian Cobra Naja h. haje (Squamata: Serpentes: Elapidae)". PLOS ONE. 10 (4) e0122185. Bibcode:2015PLoSO..1022185K. doi:10.1371/journal.pone.0122185. ISSN 1932-6203. PMC 4393244. PMID 25860015.
- ↑ Khannoon, Eraqi R.; Ollonen, Joni; Di-Poï, Nicolas (2020). "Embryonic development of skull bones in the Sahara horned viper (Cerastes cerastes), with new insights into structures related to the basicranium and braincase roof". Journal of Anatomy. 237 (1): 1–19. doi:10.1111/joa.13182. ISSN 1469-7580. PMC 7309284. PMID 32242931.
- ↑ Jollie, Malcolm T. (1960-06-01). "The head Skeleton of the Lizard". Acta Zoologica. 41 (1–2): 1–64. Bibcode:1960AcZoo..41....1J. doi:10.1111/j.1463-6395.1960.tb00474.x. ISSN 1463-6395.
- ↑ Gower, David J. (2002-09-01). "Braincase evolution in suchian archosaurs (Reptilia: Diapsida): evidence from the rauisuchian Batrachotomus kupferzellensis". Zoological Journal of the Linnean Society. 136 (1): 49–76. doi:10.1046/j.1096-3642.2002.00025.x. ISSN 0024-4082.
- ↑ Korneisel, Dana E.; Vice, Rebekah; Maddin, Hillary C. (2022). "Anatomy and development of skull–neck boundary structures in the skeleton of the extant crocodylian Alligator mississippiensis". The Anatomical Record. 305 (10): 3002–3015. doi:10.1002/ar.24834. ISSN 1932-8494. PMID 34846803.
- ↑ Currie, Philip J.; Zhao, Xi-Jin (1993). "A new troodontid (Dinosauria, Theropoda) braincase from the Dinosaur Park Formation (Campanian) of Alberta". Canadian Journal of Earth Sciences. 30 (10): 2231–2247. Bibcode:1993CaJES..30.2231C. doi:10.1139/e93-194.
- ↑ Sereno, Paul C. (1991-06-20). "Lesothosaurus, "Fabrosaurids," and the early evolution of Ornithischia". Journal of Vertebrate Paleontology. 11 (2): 168–197. Bibcode:1991JVPal..11..168S. doi:10.1080/02724634.1991.10011386. ISSN 0272-4634.
- 1 2 Huxley, Thomas Henry (1864). Lectures on the elements of comparative anatomy: On the classification of animals and on the vertebrate skull. London: J. Churchill.
- ↑ Huxley, Thomas H. (1857). "The Croonian Lecture: --On the Theory of the Vertebrate Skull". Proceedings of the Royal Society of London. 9: 381–457. ISSN 0370-1662. JSTOR 111524.
- ↑ Cite error: The named reference
:3was invoked but never defined (see the help page). - ↑ Patterson, Colin (1975-01-02). "The braincase of Pholidophorid and Leptolepid fishes, with a review of the Actinopterygian braincase". Philosophical Transactions of the Royal Society of London. B, Biological Sciences. 269 (899): 275–579. Bibcode:1975RSPTB.269..275P. doi:10.1098/rstb.1975.0001. ISSN 0080-4622. PMID 234190.