BIOL 121 Lecture Notes - Lecture 33: Weight-Bearing, Humerus, Devonian
Document Summary
Detrital inputs from terrestrial and wetlands vegetation provided a trophic base for increasingly complex food webs. Exploitation of these stable and productive wetlands probably provided driving force behind the evolution of tetrapods. Fish began to exploit these stable and productive shallow water (wetlands) Adaptations and features enabling fish and early tetrapods to use shallow habitats would later enable them to expand onto the land. Amphibian lineage that invaded land evolved from a group of bony fishes called sarcopterygians that already possessed adaptations to life in the waters of wetlands (which were also preadaptations for life in the terrestrial environment. For example, the bases of their pectoral & pelvic fins were lobed and strengthened internally by bones (sarcopterygians referred to as lobe-finned fishes) Bones in the limbs of amphibians are homologous to the bones of lobe finned fishes (sarcopterygians ) Note that: - the fish limbs did not have the distal components (wrist/ankle region, metacarpals/metatarsals & phalanges) of the tetrapod limb.
