Bowers, Sammy (2012) Prehistoric vertebrates and prehistoric invertebrates. White Word Publications, Delhi, India. ISBN 9788132342175
Preview |
Text
Prehistoricvertebrates_Sammy.pdf - Published Version Download (5MB) | Preview |
Abstract
Acanthostega (meaning Spiny Roof) is an extinct labyrinthodont genus, among the first vertebrate animals to have recognizable limbs. It appeared in the Upper Devonian (Famennian) about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and the first tetrapods fully capable of coming onto land. It had eight digits on each hand (the number of digits on the feet is unclear) linked by webbing, it lacked wrists, and was generally poorly adapted to come onto land. Acanthostega also had a remarkably fish-like shoulder and forelimb. The front foot of Acanthostega could not bend forward at the elbow, and thus could not be brought into a weight bearing position, appearing to be more suitable for paddling or for holding on to aquatic plants. It had lungs, but its ribs were too short to give support to its chest cavity out of water, and it also had gills which were internal and covered like those of fish, not external and naked like those of some modern amphibians which are almost wholly aquatic Acanthostega is the first tetrapod to show the shift in locomotory dominance from the pectoral to pelvic girdle. There are many morphological changes that allowed the pelvic girdle of Acanthostega to become a weight-bearing structure.
| Item Type: | Book |
|---|---|
| Subjects: | Q Science > QL Zoology |
| Divisions: | Electronic Books |
| Depositing User: | Esam @ Hisham Muhammad |
| Date Deposited: | 02 Jan 2023 02:05 |
| Last Modified: | 02 Jan 2023 02:05 |
| URI: | http://odlsystem2.utm.my/id/eprint/3872 |
Actions (login required)
 |
View Item |