BIOL 2030 Lecture Notes - Lecture 17: Mole Salamander, Pituitary Gland, Terrestrial Animal
Document Summary
Life history: anura, caudate (paedomorphosis, gas exchange, introduction. Class amphibia: order gymnophiona (apoda) caecillians. Viviparity common: order urodela (caudata) salamanders/newts, order anura (salientia) frogs/toads. 1: occupy a vast array of habitats (nut always near water, variations in body size pronounced (1cm to 30cm in length, sophisticated vocalizations for communication. Invasion of land in the devonian period (400 million years ago). Devonian period = the age of fishes: bony fishes had diversified and flourished, particularly in freshwater, devonian: mild temperatures and alternating droughts and floods, unstable freshwater aquatic environments, aquatic freshwater vertebrates evolved two key features: Gills are unsuitable for gas exchange in air. Lungs developed as an outgrowth of the foregut. Improved efficiency in gas exchange by sacculation and vascularization of gas-filled space. Tetrapod limb evolution: eusthenopteron devonian lobe-fin fish: 380 million years ago, gaspe, quebec. Tetrapod limb evolution: tiktaalik devonian intermediate (neither lobe-fin fish or true tetrapod: 375 million years ago, ellesmere island, canadian arctic.
