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Tooth replacement in early sarcopterygians
Mark Doeland1,2, Aidan M C Couzens1, Philip C J Donoghue3
1Naturalis Biodiversity Center, Postbus 9517, 2300 RA Leiden, The Netherlands.
Royal Society Open Science
|December 13, 2019
Summary
Early vertebrate tooth replacement patterns are clarified by studying fossil fishes like Onychodus and Eusthenopteron. New data reveal complex tooth replacement in sarcopterygians, suggesting a stem-osteichthyan origin for rotational tooth shedding.
Area of Science:
- Paleontology
- Evolutionary Biology
- Vertebrate Anatomy
Background:
- Tooth replacement is a key vertebrate innovation, but early evolution remains unclear.
- Existing knowledge on tooth replacement in jawed vertebrates is varied, with limited fossil evidence from sarcopterygian fishes.
Purpose of the Study:
- To investigate early tooth replacement patterns in sarcopterygian fishes.
- To provide new anatomical data on tooth replacement in fossil and extant sarcopterygians.
Main Methods:
- Microfocus X-ray microtomography
- Synchrotron radiation-based X-ray microtomography
- Anatomical analysis of fossil specimens (Onychodus, Eusthenopteron, Tiktaalik) and extant Latimeria.
Main Results:
- Early sarcopterygians developed replacement teeth on the jaw surface, similar to stem-osteichthyans, with resorption of damaged teeth.
- Spatial and temporal variations in resorption and replacement tooth development were observed within jaws.
- Onychodus exhibited tooth shedding via anterior rotation and resorption, with posterior addition of new teeth, a pattern potentially shared with stem-osteichthyans.
Conclusions:
- Rotational replacement of anterior dentition may be a primitive stem-osteichthyan trait.
- The evolutionary history of tooth replacement in vertebrates is more complex than previously understood.
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