BIOL 330 Lecture Notes - Lecture 8: Tetrapod, Keratin, Appendicular Skeleton
Document Summary
Living on land: evolutionary context and physiological adjustments. Tetrapods are related to lobe-finned fishes (lungfishes, coelacanths); some lineages become secondarily fully aquatic, others fully terrestrial. Amniotes have radiated into most terrestrial life zones and developed feeding and locomotor specializations. Tetrapods did not evolve to live on land, the traits they developed were beneficial to animals still living in water (but were better suited for land). Early tetrapods called early tetrapodomorphs derived fish in shallow waters. What are advantages of terrestrial activity: avoidance of seasonal droughts. Permits an animal to have a long neck (generates a large enough pressure differential to draw air down a long, thin tube) A long neck provides more space, for innervation of forelimbs (more complex in amniotes. Presence of an egg shell: provides support, restricts water movement into/out of the egg, permits reproduction in areas that may not be suitable for amniotes. How do tetrapods get support on land: production of larger offspring.