Quick Facts Scientific classification, Subclades ...

Acrodonta Temporal range: Early Cretaceous- present, 125–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Common chameleon, Chamaeleo chamaeleon
Common Agama Agama agama
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Suborder:	Iguania
Clade:	Chamaeleontiformes
Clade:	Acrodonta Cope, 1864
Subclades
†Barbaturex †Bharatagama? †Gueragama Chamaeleonidae Agamidae

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Acrodonta are a subclade of iguanian squamates 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, was found in Brazil, making it the only known American representative of the group.^[1]

The group is eponymously named from their acrodont dentition, whereby the teeth are consolidated with the summit of the alveolar ridge of the jaw without sockets.^[2] There are, however, other animals that have acrodont dentition such as tuataras.^[3]

Usually acrodonts are divided into two families Chamaeleonidae and Agamidae, there are a few studies that suggest chameleons are nested within Agamidae.^[4][5] In order to maintain the familial status of Chamaeleonidae some authors suggested placing the clades Uromastycinae and Leiolepidinae in a third family Leiolepididae.^[4][5] However a majority of papers concerning acrodont phylogenetics support the traditional dichotomy of the group.^[6][7][8][9] The Acrodonta (lizard) is the oldest iguanian lizard from the African continent. Scientists just discovered new fossils of this lizard that date all the way back to the Mesozoic Era. This indicates that Acrodontan lizards had a widespread geographical distribution in Gondwana, the supercontinent that included Africa. Meaning that they had a extensive role in the evolution of lizards especially iguanas.

Below is the phylogeny of the acrodont lineages after Pyron et al. (2013):^[8]

The extinct Arretosauridae (Paleogene iguanians from Central Asia) are also sometimes classified in Acrodonta. However, other studies instead suggest it to be a sister group to the Crotaphytidae in Pleurodonta.^[10][11] <refVullo, R., Bailon, S., Dauphin, Y., Monchot, H., & Allain, R. (2023, March). A reappraisal of Jeddaherdan Aleadonta (squamata: Acrodonta), the purported oldest iguanian lizard from Africa. NASA/ADS. https://ui.adsabs.harvard.edu/abs/2023CrRes.14305412V/abstract/ref>