Retention of fish-like odontode overgrowth in Permian tetrapod dentition supports outside-in theory of tooth origins.

ABSTRACT: Teeth are often thought of as structures that line the margins of the mouth; however, tooth-like structures called odontodes are commonly found on the dermal bones of many Palaeozoic vertebrates including early jawless fishes. 'Odontode' is a generalized term for all tooth-like dentine structures that have homologous tissues and development. This definition includes true teeth and the odontodes of early 'fishes', which have been recently examined to gain new insights into the still unresolved origin of teeth. Two leading hypotheses are frequently referenced in this debate: the 'outside-in' hypothesis, which posits that dermal odontodes evolutionarily migrate into the oral cavity, and the 'inside-out' hypothesis, which posits that teeth originated in the oropharyngeal cavity and then moved

SUBMITTER: Haridy Y 

PROVIDER: S-EPMC6769137 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature