BIOL-3030 Midterm: Tetrapod Origin
Document Summary
Tetrapods are a derived clade within the sarcopterygians. They are characterized by having fingers and toes not fins. They can now breathe with mouth closed, breathe air in while nostrils just up above the water. Slow loss of certain fin structures, soon becomes dactylous limbs. Mosaic evolution everything isn"t transitioning at the same time. There are different parts of the body changing at different rates. Evolution of tetrapods appears to have occurred in the forelimbs before the hind limbs. Polydactylous describing the numerous fingers and toes on the hands and feet. The first tetrapods were aquatic, so these features were not necessarily for living on land. The last thing to appear in a tetrapod embryo are the digits. There may be an advantage to developing more quickly. If you shorten your development some things may not appear. If development is truncated, then some of the numerous fingers and toes may not have been developed.
