Bio 1B Lecture Outline please print and bring along Fall 2008 B D Mishler Dept of Integrative Biology 2 6810 bmishler berkeley edu Evolution lecture 8 Fossils Precambrian and Paleozoic Nov 19th 2008 required reading 656 658 ch 32 8th 628 630 ch 32 in 7th optional for background 698 735 ch 34 8th 671 707 ch 34 7th Summary of topics for today Review and overview of the history of life Mass extinctions Summary of the geological time tale eras periods and epochs Continental drift plate tectonics Precambrian period Paleozoic era see notes from last time Major features of the early fossil record mass extinctions times during which rates of extinction were very much higher than during intervening times a possible link to impacts of extraterrestrial bodies stromatolites banded layers of sediments limestone containing bacterial mats cyanobacteria photosynthetic oxygen producing bacteria caused a turnover in the atmosphere to oxygen 2 BYA See Table 25 1 8th Table 26 1 7th PRECAMBRIAN 4 6 billion to 542 MYA In billion years BYA 15 Big Bang formation of the universe 4 6 earth forms 3 8 origin of life 3 5 oldest known definitive evidence of life on earth prokaryotes 2 oldest known definitive fossils of eukaryotes well defined nucleus 1 5 eukaryotes proliferate endosymbiotic theory in addition to the nuclear genome mitochondria have a genome as do the chloroplasts of cells The organization and expression of mitochondria and chloroplast genomes show considerable similarities to that of some prokaryote cells suggesting that the evolution of Evolution 8 pg 1 eukaryote cells involved a process in which a precursor to the eukaryote cell protoeukaryote engulfed endocytosed a prokaryote cell the symbiont see Fig 28 2 8th Fig 26 13 7th Such a process is termed endosymbiosis and this is thought to have conferred a selective advantage to the resulting new cell The genomes of the engulfed prokaryote cell and the host cell are envisaged to have given rise to the present day mitochondrial and nuclear genes respectively 700 Myr origin of first animals soft bodied marine invertebrates Doushantuo fossils Southern China sponges animal embryos cyanobacteria multi cellular algae shallow water marine invertebrate habitat dominated by photosynthetic organisms scattered among them are tiny animals who filtered organic debris from the water Ediacaran fossils South Australia large sponges jellyfish many burrows tracks and other trace fossils from animals no animals with shells were present shallow water marine habitats containing a diversity of animal species none have limbs or mouths or feeding appendages suggests animals burrowed in the sediment sat immobile on the sea floor or floated in the water and did actively hunt and capture food but simply filtered organic materials from their surroundings fig 32 4 8th fig 32 5 7th 542 Myr Paleozoic era Cambrian Ordovician Silurian Devonian Carboniferous Permian Beginning of an abundant fossil record Cambrian explosion adaptive radiation this was a time of great innovation the appearance of hard shells and exoskeletons all the phyla existing today originated early in the Cambrian and there were many diverse algae see fig 32 5 8th Fig 32 6 7th There was a tremendous increase in the size and morphological complexity of animals accompanied by diversification in how they made a living The Cambrian seas were filled with animals that had eyes mouths limbs and shells They were predators scavengers filter feeders and grazers Burgess Shale British Columbia Canada and Chengjiang China fossils few if any species of the Ediacara are seen new species of sponges and jellyfish are seen and entirely new groups present as well especially the arthropods and mollusks and even a chordate Hallucigenia Opabinia Evolution 8 pg 2 Cone of increasing diversity or Decimation and diversification Marine Animals invertebrates with shells exoskeletons e g trilobites marine arthropods that were extremely abundant in the Paleozoic primitive vertebrates jawless fish jawed fish Fig 34 2 34 13 and 34 14 8th Fig 34 13 and 34 20 7th Transition to Land what are the major problems land organisms had to deal with reproduction UV radiation water relationships animals on dry land arthropods millipedes scorpions spiders amphibians Fig 34 19 8th 7th and insects wingless on dry land cockroaches mites crabs mammal like reptiles synapsids land plants early species were poikilohydric i e their water content matched that of the surrounding environment and desiccation tolerant gymnosperms Fig 30 5 8th Fig 29 7 7th evolution of the seed reptiles Fig 34 24 8th Fig 34 23 7th extensive forests of vascular plants with giant club mosses horsetails and ferns in the Carboniferous and insects with wings Fig 29 16 8th Fig 29 15 7th Mass extinction at end of Permian primarily marine trilobites extinct Pangaea forms sea levels reduced volcanic activity Questions relating to lectures on the fossil record 1 Do self quiz questions 2 3 on page 735 of the 8th edition or do self quiz question 2 on page 637 of the 7th edition Evolution 8 pg 3
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