Meckelian cartilage

Meckelian cartilage

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. [http://www.palaeos.com/Vertebrates/Bones/Gill_Arches/Meckelian.html The Gill Arches: Meckel's Cartilage] at Palaeos]

In early fish and in chondrichthyans (cartilaginous fish such as sharks, 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 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 mammals.

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  • Meckelian cartilage — Meckelian Meck*e li*an, a. (Anat.) Pertaining to, or discovered by, J. F. Meckel, a German anatomist. [1913 Webster] {Meckelian cartilage}, the cartilaginous rod which forms the axis of the mandible; called also {Meckel s cartilage}. [1913… …   The Collaborative International Dictionary of English

  • meckelian cartilage — noun see meckelian bar …   Useful english dictionary

  • Meckelian — Meck*e li*an, a. (Anat.) Pertaining to, or discovered by, J. F. Meckel, a German anatomist. [1913 Webster] {Meckelian cartilage}, the cartilaginous rod which forms the axis of the mandible; called also {Meckel s cartilage}. [1913 Webster] …   The Collaborative International Dictionary of English

  • Meckelian groove — The Meckelian groove (or Meckel s groove, Meckelian fossa, or Meckelian foramen, or Meckelian canal) is an opening in the medial (inner) surface of the mandible (lower jaw) which exposes the Meckelian cartilage.[1] Modern eutherian mammals (which …   Wikipedia

  • meckelian bar — meˈkēlēən noun or meckelian cartilage or meckelian rod Usage: usually capitalized M Etymology: Johann F. Meckel died 1833 + English ian : meckel s cartilage …   Useful english dictionary

  • Meckel's cartilage — Meckelian Meck*e li*an, a. (Anat.) Pertaining to, or discovered by, J. F. Meckel, a German anatomist. [1913 Webster] {Meckelian cartilage}, the cartilaginous rod which forms the axis of the mandible; called also {Meckel s cartilage}. [1913… …   The Collaborative International Dictionary of English

  • Meckel's cartilage — Head and neck of a human embryo eighteen weeks old, with Meckel’s cartilage and hyoid bar exposed …   Wikipedia

  • Recapitulation theory — The theory of recapitulation, also called the biogenetic law or embryological parallelism and often expressed as ontogeny recapitulates phylogeny is a disproven hypothesis that in developing from embryo to adult, animals go through stages… …   Wikipedia

  • Mentomeckelian — Men to*meck*e li*an, a. [1st mental + Meckelian.] (Anat.) Of or pertaining to the chin and lower jaw. n. The bone or cartilage forming the anterior extremity of the lower jaw in some adult animals and the young of others. [1913 Webster] …   The Collaborative International Dictionary of English

  • Gnathostomata — Taxobox name = Gnathostomata fossil range = fossilrange|462|0Late Ordovician Recent image width= 200px image caption = Gnathostomata are jawed vertebrates regnum = Animalia phylum = Chordata subphylum = Vertebrata infraphylum = Gnathostomata… …   Wikipedia

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