Polyphyodont
A polyphyodont is any animal whose
Polyphyodonts include most toothed fishes, many reptiles such as crocodiles and geckos,[2][3][4] and most other vertebrates, mammals being the main exception.
Growth
New, permanent teeth grow in the jaws, usually under or just behind the old tooth, from stem cells in the dental lamina.[5] Young animals typically have a full set of teeth when they hatch; there is no tooth change in the egg. Within days, tooth replacement begins, usually in the back of the jaw continuing forward like a wave. On average a tooth is replaced every few months.
Crocodilia
Evolution in mammals
The manatees have no incisor or canine teeth, just a set of cheek teeth, which are not clearly differentiated into molars and premolars. These teeth are continuously replaced throughout their life with new teeth growing at the rear as older teeth fall out from farther forward in the mouth, a process known as "hind molar progression" or “marching molars”.[9]
See also
References
- S2CID 206417026.
- ^ "Mechanism of tooth replacement in Leopard geckos]". Archived from the original on 2015-03-12.[self-published source?]
- PMID 15696682.
- PMID 24019968.
- PMID 23788284.
- PMID 24023957.
- ^ PMID 23671090.
- PMID 23874921.
- ^ "Manatee adaptations: the head". Archived from the original on 2016-03-03. Retrieved 2013-11-07.[unreliable source?]
Further reading
- Tucker, Abigail S.; Fraser, Gareth J. (January 2014). "Evolution and developmental diversity of tooth regeneration" (PDF). Seminars in Cell & Developmental Biology. 25–26: 71–80. PMID 24406627.
- Fraser, Gareth J.; Meredith Smith, Moya (15 March 2011). "Evolution of developmental pattern for vertebrate dentitions: an oro-pharyngeal specific mechanism". Journal of Experimental Zoology Part B: Molecular and Developmental Evolution. 316B (2): 99–112. PMID 21328527.