Domain: Eukarya Kingdom: Animalia Who are the Animalia?-Eukaryotic-Multicellular-Heterotrophic (**Feed by indigestion)-Most animals have:-Sense organs-Nervous system-Muscles-Digestive tract-Sex organsBrief History of the World1. Hadean Eon (4.6 - 3.8 bya)-Earth & Moon formed as solid bodies2. Archaen Eon (3.8 – 2.6 bya)-Origin of Life-Origin of Prokaryotes-Fermentation-Photosynthesis3. Proterozoic Eon (2.6 – 0.57 bya)-Continental Drift begins-O2 Revolution-Krebs Cycle-Origin of Eukaryotes-Ediacaran Period (Precambrian) – First multicellular animals (700 - 650 mya)Four Precambrian fossils those are difficult to classify:1. Tribrachidium2. Spriggina 3. Kimberella4. Dickinsonia4. Phanerozoic Eon (0.57 bya – Today)-Cambrian Explosion (543 – 490 mya)- About 35 animal phyla originated in ~ 50mya-First skeletal remains-Origin of most major multicellular phyla-Came from gradual evolution from Edicarian speciesTwo Major Questions1. Why and when did multicellularity arise?-Greater than 700 mya-Advantages of:-Large size-Cell specialization (Division of labor)-Originated when unicellular organisms stayed together after cell division2. What cause the Cambrian Explosion?1. There was a real “explosion.”-ex. In a few million years all major phyla evolved from protozoans2. Major forms were already present.-They were small and without skeletons-They did not fossilize well.-Then at the Cambrian they increases in size and developed skeletons (DNA evidence supports this view)What could have prompted the increase in size and skeletal development?1. Predation2. Oxygen RevolutionOxygen
View Full Document
Unlocking...