From the symposium on Starting from Fins: Parallelism in the Evolution of Limbs and Genitalia.
Fins to limbs: what the fossils say1
Version of Record online: 16 SEP 2002
2002 BLACKWELL PUBLISHING, INC.
Evolution & Development
Volume 4, Issue 5, pages 390–401, September 2002
How to Cite
Coates, M. I., Jeffery, J. E. and Ruta, M. (2002), Fins to limbs: what the fossils say. Evolution & Development, 4: 390–401. doi: 10.1046/j.1525-142X.2002.02026.x
- Issue online: 16 SEP 2002
- Version of Record online: 16 SEP 2002
SUMMARY A broad phylogenetic review of fins, limbs, and girdles throughout the stem and base of the crown group is needed to get a comprehensive idea of transformations unique to the assembly of the tetrapod limb ground plan. In the lower part of the tetrapod stem, character state changes at the pectoral level dominate; comparable pelvic level data are limited. In more crownward taxa, pelvic level changes dominate and repeatedly precede similar changes at pectoral level. Concerted change at both levels appears to be the exception rather than the rule. These patterns of change are explored by using alternative treatments of data in phylogenetic analyses. Results highlight a large data gap in the stem group preceding the first appearance of limbs with digits. It is also noted that the record of morphological diversity among stem tetrapods is somewhat worse than that of basal crown group tetrapods. The pre-limbed evolution of stem tetrapod paired fins is marked by a gradual reduction in axial segment numbers (mesomeres); pectoral fins of the sister group to limbed tetrapods include only three. This reduction in segment number is accompanied by increased regional specialization, and these changes are discussed with reference to the phylogenetic distribution of characteristics of the stylopod, zeugopod, and autopod.