Meckelian cartilage: Difference between revisions
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#REDIRECT Meckel's cartilage |
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{{mergeto|Meckel's cartilage|discuss=Talk:Meckel's cartilage#Merger proposal|date=October 2009}} |
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The '''Meckelian Cartilage''', also known as "Meckel's Cartilage", is a piece of [[cartilage]] ("gristle") from which the mandibles (lower jaws) of [[vertebrates]] evolved. Originally it was the lower of two cartilages which supported the first [[gill]] arch (nearest the front) in early [[fish]]. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw.<ref name="PalaeosMeckelian">[http://www.palaeos.com/Vertebrates/Bones/Gill_Arches/Meckelian.html The Gill Arches: Meckel's Cartilage] at [[Palaeos]]</ref> |
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In early fish and in [[chondrichthyans]] (cartilaginous fish such as [[shark]]s, which are not [[primitive]] in any sense of the word), the Meckelian Cartilage continued to be the main component of the lower jaw. But in the adult forms of [[Osteichthyes| osteichthyans]] (bony fish) and their descendants ([[amphibians]], [[reptiles]], [[birds]], [[mammals]]), the cartilage was covered in bone - although in their [[embryos]] the jaw initially develops as the Meckelian Cartilage. In all [[tetrapods]] the cartilage partially ossifies (changes to bone) at the rear end of the jaw and becomes the [[articular]] bone, which forms part of the jaw joint in all tetrapods except [[Evolution of mammals| mammals]].<ref name="PalaeosMeckelian" /> |
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==References== |
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{{reflist}} |
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[[Category:Skeletal system]] |
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[[ca:Cartílag de Meckel]] |
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Revision as of 20:05, 24 June 2010
- REDIRECT Meckel's cartilage