Morphological and histological changes of dermal scales during the fish-to-tetrapod transition
Article first published online: 29 JUN 2010
© 2010 The Author. Acta Zoologica © 2010 The Royal Swedish Academy of Sciences
Volume 92, Issue 3, pages 281–302, July 2011
How to Cite
Witzmann, F. (2011), Morphological and histological changes of dermal scales during the fish-to-tetrapod transition. Acta Zoologica, 92: 281–302. doi: 10.1111/j.1463-6395.2010.00460.x
- Issue published online: 9 JUN 2011
- Article first published online: 29 JUN 2010
- Accepted for publication: 21 May 2010
- Early tetrapods;
- integument Palaeozoic;
Witzmann F. (2011). Morphological and histological changes of dermal scales during the fish-to-tetrapod transition. —Acta Zoologica (Stockholm) 92: 281–302.
The gastral scales of limbed tetrapodomorphs evolved from the ‘elpistostegid’-type of scale by an enlargement and differentiation of the articulation facets and a shortening and broadening of the keel. These changes caused a tighter connection between gastral scales within a scale row and a greater overlap between the rows. Dorsal round scales of limbed tetrapodomorphs developed from a gastral scale-type by an alteration of the ontogenetic pathway. The posterolateral direction of scale rows in ‘elpistostegids’ was retained in the gastral scalation of most limbed tetrapodomorphs, whereas the arrangement of round dorsal scales is modified to a transverse orientation. Both gastral and dorsal scales of limbed tetrapodomorphs consist solely of parallel-fibred bone with circumferential growth marks. The proportionally larger overlap surfaces of gastral scales and their mode of articulation in the ventral midline indicate that the body of limbed tetrapodomorphs might have been more flexible than that of their finned relatives. The alteration of dermal scales was one of the most rapid morphological changes during the fish-to-tetrapod transition. Once established, gastral and dorsal scales were retained as a conservative character in different lineages of basal tetrapods, in both the amphibian and the amniote lineages.