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The articular bone is part of the lower jaw of most
vertebrates Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic ma ...

vertebrates
, including most
jawed fish Gnathostomata are the jawed vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With few excepti ...
,
amphibians Amphibians are ectotherm File:Junonia lemonias DSF by Kadavoor.JPG, ''Junonia lemonias'' is basking under the sun. An ectotherm (from the Ancient Greek, Greek ἐκτός (''ektós'') "outside" and θερμός (''thermós'') "hot") is an o ...

amphibians
,
birds Birds are a group of s constituting the Aves , characterised by s, toothless beaked jaws, the of eggs, a high rate, a four-chambered , and a strong yet lightweight . Birds live worldwide and range in size from the to the . There ar ...

birds
and various kinds of
reptiles Reptiles, as most commonly defined, are the animals in the class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or o ...

reptiles
, as well as ancestral
mammals Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the R ...
.


Anatomy

In most animals, the articular bone is connected to two other lower jaw bones, the suprangular and the angular. Developmentally, it originates from the embryonic mandibular cartilage. The most
caudal Caudal may refer to: Anatomy * Caudal (anatomical term) Standard anatomical terms of location deal unambiguously with the anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure o ...
portion of the mandibular cartilage ossifies to form the articular bone, while the remainder of the mandibular cartilage either remains cartilaginous or disappears.


In snakes

In
snakes Snakes are elongated, limbless, carnivorous A carnivore , meaning "meat Meat is animal flesh that is eaten as food. Humans have hunted and killed animals for meat since prehistoric times. The advent of civilization allowed the domes ...

snakes
, the articular, surangular, and prearticular bones have fused to form the compound bone. The mandible is suspended from the quadrate bone and articulates at this compound bone.


Function


In amphibians and reptiles

In most tetrapods, the articular bone forms the lower portion of the jaw joint. The upper jaw articulates at the
quadrate bone 300px, A schematic of an anapsid skull showing the location of major dermal bones of the upper skull, including the quadrate bone (q).The quadrate bone is a skull bone in most tetrapods, including amphibians, sauropsids (reptiles, birds), and ear ...
.


In mammals

In
mammals Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the power of the R ...
, the articular bone evolves to form the
malleus The malleus, or hammer, is a hammer-shaped small bone or ossicle The ossicles (also called auditory ossicles) are three bone A bone is a Stiffness, rigid tissue (anatomy), tissue that constitutes part of the vertebrate skeleton in animals. ...

malleus
, one of the mammalian
ossicles The ossicles (also called auditory ossicles) are three bone A bone is a rigid tissue Tissue may refer to: Biology * Tissue (biology), an ensemble of similar cells that together carry out a specific function * ''Triphosa haesitata'', a spe ...
of the middle ear. This is an
apomorphy 279px, trait states. In phylogenetics, apomorphy and synapomorphy refer to derived characters of a clade A clade (; from grc, , ''klados'', "branch"), also known as a monophyletic group or natural group, is a group of organisms that are mon ...
of the mammalian clade, and is used to determine the fossil transition to mammals. It is
analogous Analogy (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 million ...
to, but not homologous to the
articular process The articular processes or zygapophyses (Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is a ...
of the
lower jaw In anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any ind ...

lower jaw
. After the loss of the quadrate-articular joint, the squamosal and dentary bones form the new jaw joint in mammals.


References

Skeletal system {{Commons cat, Skeletal system A skeleton (endoskeleton) is made up of bones. ''See also:'' :Bone products Musculoskeletal system ...
Vertebrate anatomy {{Vertebrate-anatomy-stub