BIO SCI 94 Lecture 14: Lecture 14

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Nancy Burley

Document Summary

Shelled eggs: reptiles, birds, monotremes (a breed of mammals) The theropod hypothesis: origin of birds from maniraptors (coelosauria) Origin of dino feathers = origin of flight. Cladistically speaking, birds are chordates, diapsids, reptiles, and dinosaurs. Emerged in synapsid lineage (200 mya) shortly after dinosaurs (220 mya) Diapsids dinural --> cynodonts nocturnal insectivores --> mammals. In comparison with amphibia and fish, birds and mammals produce fewer zygotes that have a better change of surviving. Early histories of protostomes and deuterostomes similar: organs to move water and extract prey from mud or ocean water. Consequences of land colonization quite different: protostome size more constrained than deuterostomes due to exoskeleton. Amniotic egg (350 mya) --> reproduction on land; amniotes drove most amphibia to extinction. Mc/fossil evidence --eutherians and birds slightly older than flowering plants. Parallels and difference between plants and chordates is in the colonization of land, including reproduction. Review: key innovations and key lineages, and timeline of fossil record (35. 11)