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Thecodont tooth attachment and replacement in bolosaurid parareptiles
Adam J Snyder1, Aaron R H LeBlanc2, Chen Jun3,4
1Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada.
Peerj
|May 23, 2020
Summary
Permian bolosaurid parareptiles possessed unique thecodont tooth implantation with deep roots, the oldest known in amniotes. Their tooth replacement was highly synchronized, with developing teeth found within the pulp cavities of functional teeth.
Area of Science:
- Paleontology
- Vertebrate Zoology
- Evolutionary Biology
Background:
- Permian bolosaurid parareptiles exhibit unique dentition compared to other Paleozoic amniotes.
- Bolosaurids possess complex tooth crowns and complete tooth rows, unlike contemporaries with simpler teeth and replacement gaps.
Purpose of the Study:
- To analyze the specialized dentition and tooth replacement patterns in Permian bolosaurid parareptiles.
- To investigate the developmental and histological aspects of bolosaurid teeth using advanced imaging techniques.
Main Methods:
- Histological analysis of fossilized teeth.
- High-resolution computed tomography (CT) scans of bolosaurid jaws and teeth.
- Examination of specimens including *Bolosaurus* (North America) and *Belebey* (Russia).
Main Results:
- Bolosaurid teeth display thecodont implantation with deep roots, the earliest known instance in amniotes.
- CT scans revealed developing replacement teeth within the pulp cavities of functional teeth.
- Tooth replacement appears highly synchronized along the tooth row, linked to lingual pits in the jaw.
Conclusions:
- Bolosaurid tooth development and replacement patterns are distinct among early amniotes.
- Thecodont tooth implantation in bolosaurids evolved independently and predates similar developments in archosauromorphs and synapsids.
- Advanced development of replacement teeth within pulp cavities allowed prolonged function of the preceding tooth generation.
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