Acrodonta are a subclade of
iguanian squamate
Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, it ...
s consisting almost entirely of Old World taxa. Extant representation include the families
Chamaeleonidae (chameleons) and
Agamidae (dragon lizards), with at least over 500 species described. A fossil genus, ''
Gueragama
''Gueragama'' is an extinct genus of iguanian lizard from the Late Cretaceous of Brazil. It belongs to a group of iguanians called Acrodonta, whose living members include chameleons and agamids and are currently restricted to the Old World. ' ...
'', was found in
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
, making it the only known
American
American(s) may refer to:
* American, something of, from, or related to the United States of America, commonly known as the "United States" or "America"
** Americans, citizens and nationals of the United States of America
** American ancestry, pe ...
representative of the group.
The group is eponymously named from their
acrodont Acrodonty (from Greek ''akros'' 'highest' + ''dont'' 'tooth') is an anatomical placement of the teeth at the summit of the alveolar ridge of the jaw, without sockets, characteristic of bony fish. Functionally, acrodont tooth implantation may be rela ...
dentition, whereby the teeth are consolidated with the summit of the
alveolar ridge
The alveolar process () or alveolar bone is the thickened ridge of bone that contains the tooth sockets on the jaw bones (in humans, the maxilla and the mandible). The structures are covered by gums as part of the oral cavity.
The synonymous t ...
of the jaw without sockets. There are, however, other animals that have acrodont dentition such as
tuatara
Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand. Despite their close resemblance to lizards, they are part of a distinct lineage, the order Rhynchocephalia. The name ''tuatara'' is derived from the Māori language and m ...
s.
Systematics
Usually acrodonts are divided into two families Chamaeleonidae and Agamidae, there are a few studies that suggest chameleons are nested within Agamidae.
In order to maintain the familial status of Chamaeleonidae some authors suggested placing the clades
and
Leiolepidinae
''Leiolepis'', commonly known as butterfly lizards or butterfly agamas ( th, แย้), are group of agamid lizards. They are native to Peninsular Malaysia, Thailand, Myanmar, Laos, Cambodia, Indonesia, Ryukyu Islands (Japan), Vietnam, and Hain ...
in a third family Leiolepididae.
[ However a majority of papers concerning acrodont phylogenetics support the traditional dichotomy of the group.][
]
References
Iguanomorpha
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