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Sesamoids in anurans: new data, old issues
María Laura Ponssa1, Javier Goldberg, Virginia Abdala
1Instituto de Herpetología, Fundación Miguel Lillo-CONICET, Tucumán, Argentina. mlponssa@hotmail.com
Anatomical Record (Hoboken, N.J. : 2007)
|July 24, 2010
Summary
This study reveals that anuran (frog) sesamoids, small bones in tendons, often develop before tendons form, challenging traditional biomechanical theories. Researchers analyzed sesamoid development and distribution across 185 frog species.
Area of Science:
- Comparative anatomy
- Vertebrate paleontology
- Developmental biology
Background:
- Sesamoids are understudied skeletal elements in vertebrates.
- Their developmental origins and evolutionary patterns remain largely unclear.
- Existing theories often link sesamoid formation solely to biomechanical forces on tendons.
Purpose of the Study:
- To investigate the comparative anatomy and ontogeny of anuran sesamoids.
- To explore the relationship between sesamoid and tendon development in frogs.
- To map sesamoid distribution across anuran taxa and propose evolutionary patterns.
- To provide insights into tetrapod sesamoid evolution.
Main Methods:
- Ontogenetic analysis of sesamoids in two anuran species.
- Examination of related structures: tendons, muscles, and joints.
- Survey of sesamoid distribution in 185 anuran species using cleared and stained skeletal whole-mounts.
Main Results:
- Identified 54 sesamoids in anurans, with 37 unique to Leptodactylus latinasus.
- Found that many sesamoids develop prior to tendon differentiation, contradicting biomechanical origin hypotheses.
- Documented sesamoid distribution across major anuran clades (Hyloides and Ranoides).
- Most surveyed sesamoids exhibit multiple developmental origins.
Conclusions:
- Anuran sesamoid development is not solely driven by biomechanical stimuli from pre-existing tendons.
- The study provides novel data on tetrapod sesamoid homologies and evolutionary pathways.
- Findings contribute to understanding the diversity and development of sesamoids in amphibians and potentially other tetrapods.
