Caecilians are enigmatic limbless amphibians that, with a few exceptions all have an at least partly burrowing lifestyle. Although it has been suggested that caecilian evolution resulted in sturdy and compact skulls as an adaptation to their head-first burrowing habits, no relationship between skull shape and burrowing performance has been demonstrated to date. However, the unique dual jaw-closing mechanism and the osteological variability of their temporal region suggest a potential relationship between skull shape and feeding mechanics. Here, we explored the relationships between skull shape, head musculature, and in vivo bite forces. Although there is a correlation between bite force and external head shape, no relationship between bite force and skull shape could be detected. Whereas our data suggest that muscles are the principal drivers of variation in bite force, the shape of the skull is constrained by factors other than demands for bite force generation. However, a strong covariation between the cranium and mandible exists. Moreover, both cranium and mandible shape covary with jaw muscle architecture. Caecilians show a gradient between species with a long retroarticular process associated with a large and pennate-fibered m. interhyoideus posterior and species with a short process but long and parallel-fibered jaw adductors. Our results demonstrate the complexity of the relationship between form and function of this jaw system. Further studies that focus on factors such as gape distance or jaw velocity will be needed in order to fully understand the evolution of feeding mechanics in caecilians.
The relationship between head shape, head musculature and bite force in caecilians (Amphibia: Gymnophiona)
co-last authors
- Award Group:
- Funder(s): Fonds Wetenschappelijk Onderzoek
- Award Id(s): 11D5819N
- Funder(s):
- Award Group:
- Funder(s): Royal Belgian Zoological Society
- Funder(s):
- Award Group:
- Funder(s): Tournesol Travel grant
- Funder(s):
- Award Group:
- Funder(s): Bijzonder Onderzoeksfonds UGent
- Award Id(s): BOF.EXP.2017.0007
- Funder(s):
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Aurélien Lowie, Barbara De Kegel, Mark Wilkinson, John Measey, James C. O'Reilly, Nathan J. Kley, Philippe Gaucher, Jonathan Brecko, Thomas Kleinteich, Dominique Adriaens, Anthony Herrel; The relationship between head shape, head musculature and bite force in caecilians (Amphibia: Gymnophiona). J Exp Biol 2021; jeb.243599. doi: https://doi.org/10.1242/jeb.243599
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