BIOL108 Lecture Notes - Lecture 31: Ichthyostega, Acanthostega, Tiktaalik

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Shape and size of the hip socket (pelvis) reveal that fins were capable of a wide range of movements: from swimming to supporting weight (sort of) tetrapods evolved their feet for uses in water. Overall structure of the pelvis is still more fish-like. Tiktaalik s pelvis is still made of one bone (tetrapods pelvis made of three parts) Fossil record documents the change from sturdy finned fishes like tiktaalik to early amphibians. Primitive traits: gills, lateral line, long fin rays around the tail no true elbows, knees, wrists or ankles (i. e. , not weight-bearing) Couldn"t have possibly supported their weight on land. 4 limbs w/ bony digits pelvis weakly attached to vertebrate. Early amphibian (ichthyostega - recognize name) - first true tetrapod. Derived traits: limbs attached to vertebrate, weight bearing joints (e. g. , elbows, wrist, knee, ankle) ichthyostega. Thin, permeable skin sole site of gas exchange for some lungless salamanders.