01:119:160 Lecture Notes - Lecture 1: Lepospondyli, Ichthyostegalia, Notochord
1 Nov 2016
School
Department
Course
Professor
Document Summary
The cambrian explosion refers to an explosion in life - many new organisms appeared that are much more representative of the type of animals in the world today - prior to the explosion, organisms were soft-bodied and very basic. The largest mass extinction to ever occur was the permian extinction, not the cretaceous. Animals need lungs, skin, and limbs in order to transition from water to land. Crosspterygians/sarcoptergii - fish with lungs, but very calcified, so serve no purpose or for storage of fat, had labryinthodont - teeth characterized by folded sheets of dentine. Amphibia - the last stage in the pisces cladogram but technically not a part of the cladogram, four limbs (tetrapods) Actinopterygii, dipnoi, crossopterygii are separated from the other groups in the pisces cladogram based on bones - these classes are osteichthyes. Amphibia - double life life in water and on land. Evolution on land - first plants, then invertebrates, finally vertebrates.
