BIOL 1108 Lecture Notes - Lecture 38: Reptile, Tetrapod, Tiktaalik
Document Summary
There are only four fishy species of living lobe fins. The coelacanth and lungfish are the sister group to tetrapods. The transition to land occurred about 360 million years ago. Eleven animal groups made transitions to land from the water. Animal evolution - the deuterostomes and the chordates. In the lobe fins, there are bones in the fin bases extending out from the body. Tiktaalik was the transition form with wrist and finger bones plus a true neck and amphibian skull. Typical life cycle includes an aquatic larvae with gills and metamorphosis to a lunged terrestrial adult. The adults are specialized for feeding on small terrestrial animals, especially. Includes a fish like larval stage that grazes on aquatic algae insects. The amphibia are tetrapods that remain dependent on free water for reproduction. Amphibia means double life, both wet and dry. Although they evolved from heavily scaled fishes, extant amphibians have thin, porous skin. Eggs are always kept in moist environments.
