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Chapter 3
The Diversity of Life
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Guiding Questions
• What are fossils?
• How do scientists arrange organisms in natural groups?
• What is the most fundamental taxonomic division of life?
• What kinds of organisms constitute the Protista and Fungi?
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Fossils
• Tangible remains or signs of ancient organisms
• Found mostly in sedimentary rocks (why?) or sediments, especially marine sediments
• Thousands to millions of years old
Nautilus
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Fossils
• Most fossils are hard parts of organism– Teeth, skeleton
– Earthworm setae
– Insect mandibles
– Crinoid (left)- ‘sea lily’ that is actually an animal with a CaCO3 skeleton.
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Fossils
• Hard parts may be completely replaced by minerals
• This crinoid’s CaCO3 skeleton has been completely replaced by pyrite (fool’s gold).
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Fossils
• Fossilization of soft parts is rare– Requires oxygen-poor
environment– Burial in fine-grained
sediment
• Permineralization– Infilling of woody tissue
by inorganic materials– Petrified wood
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Petrified Wood
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Fossils
• Fossil need not be skeletal• Mold
– 3-D negative imprint
Brachiopod fossils (left):S = shell
M = mold
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Fossils
• Impressions– 2-D preservation of
outlines and surface features
• Carbonization (left)– Concentrated residue
of remaining carbon
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Fossils
• Trace fossils– Tracks/trackways
– Trails
– Burrows
• Provides behavioral information about extinct animals (how?)
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Fossils
• Fossils provide biased view of biota– Not all organisms are preserved (over-/under-
represented)• Rare organisms• Lacking hard parts
– Not all skeletal material is preserved• Scavengers• Transport and abrasion• Post-burial alteration of rock
– Not all fossils are exposed at the surface– Some are destroyed by plate tectonics, metamorphism,
etc.
12Putative Jellyfish fossils
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The Current Hotspot
American/Mongolian team excavating an ankylosaur fossil in the Gobi Desert in Mongolia.
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Buy Fossils Now!
• eBay http://www.ebay.com
• http://www.arizonaskiesmeteorites.com/Dinosaur_Fossils_For_Sale/
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Taxonomy
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Human Genealogy
(Who else is hanging around in your family tree?)
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Taxonomic Scheme
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species
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Taxonomic Scheme• Karl
• Plays
• Cards
• Only
• For
• Green
• Stamps
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Taxonomic Scheme• Kids
• Prefer
• Candy
• Over
• Fat
• Gooey
• Snails
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Taxonomic Scheme• Kingdom - Animal• Phyum - Chordate• Sub-phylum - Vertebrate• Class - Mammal• Order - Primate• Family - Hominid• Genus - Homo• Species - Homo sapiens
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More Mnemonics
• Animalia• Chordata• Vertebrata• Mammalia• Primata• Hominid• Homo• Homo sapiens
• Ana• Caught• Vince• Making• Piping • Hot • Ham• Sandwiches
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• A• chocolate• valentine• may• produce• hot and• heavy • sweethearts
• Animalia• Chordata• Vertebrata• Mammalia• Primata• Hominid• Homo• Homo sapiens
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• A• crystal• vase• might• possibly• hold• hybrid • sunflowers
• Animalia• Chordata• Vertebrata• Mammalia• Primata• Hominid• Homo• Homo sapiens
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• Amy• cutout• valentines for• Ma,• Pa,• her• husband and• sister
• Animalia• Chordata• Vertebrata• Mammalia• Primata• Hominid• Homo• Homo sapiens
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Chordates
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Fish Amphibian
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Reptile Mammal
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Birds
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Primates Baboon Prosimian
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The Pinnacle of Evolution?
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Other Hominids?
Bigfoot
Sasquatch
Jersey Devil
Abominable Snowman
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Other Hominids?
Neanderthal
Homo habilis
Homo erectus
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Taxonomic Groups
• Six kingdoms– Prokaryotes
• Archaeobacteria
• Eubacteria
– Eukaryotes• Plantae-producers
• Fungi-consumers
• Animalia-consumers
• Protista
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Taxonomic Groups
• Taxonomy– Study of composition and relationship of the
taxonomic groups
• Taxonomic groups– The six kingdoms and their subordinate groups
– Taxon/taxa
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Taxonomic Groups
• Linnaean taxa range from broad (phylum) to narrow (species)– Phylum-one of the major
categories of organisms– Species
• Group of individuals that can interbreed
• Name includes genus• Italicized or underlines
• Class Mammalia– Order primates
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Taxonomic Groups
• Phylogeny– “tree of life”
– structure formed by branches of species
• Cluster into groups with similar traits, equivalent to taxa– Genus (genera)
• small clusters
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Taxonomic Groups
• Clade– Cluster of species that share a
common ancestry and have homologous structures
– All species within each clade must be traceable to a common ancestor; must be monophyletic
• Cladistics• Homologous-structures
derived from the same “blueprint” of common ancestry.
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Taxonomic Groups
• Primitive traits– appear early in evolutionary
history; relatively unchanged– hagfish group traits
• Derived traits– evolved later; often much
changed from ancestral forms
– present only in some subgroups
– jaws, lungs, claws or nails, feather, fur, and mammary glands
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Taxonomic Groups
• Horse ancestry– Detailed phylogeny due to
abundant fossil record
• Three clades– Subfamilies
• All members of the modern horse family belong to Equus and originated in North America
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Prokaryotes
• Bacteria (bacterium), as a group, gain nutrition in a variety of ways– photosynthetic
– chemosynthetic
– consumers
• As a group, at least 3 billion years old
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Prokaryotes
• Archaeobacteria– Can tolerate extreme
conditions-extremophiles• very high temperatures
– hot springs
• low or no oxygen
• acidic conditions
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Prokaryotes
• Eubacteria– divided by structure of cell
walls
– Cyanobacteria• photosynthetic
– spherical or filamentous
• can form mats or scum
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Protista
• Many single celled organisms
• Some simple multicellular organisms
• Includes Algae– “seaweeds”
Amoeba
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Protista
• Protozoans– Animal-like protists
• Amoebas– change shape; no rigid form
• Flagellates– flagellum for locomotion
• Ciliates– cilia for locomotion
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Protista
• Unicellular algae– plant-like protists
• Dinoflagellates
• Diatoms
• Calcareous nannoplankton
• Originated in the Mesozoic Era– among the most important
marine producers
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Protista
• Dinoflagellates– two flagella for locomotion
• drift
– dormancy• armor in a cyst
• often fossilized as cysts
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Protista
• Diatoms– Two-part skeleton of
opal (SiO2)• Halves fit together
– Freshwater and marine• Most planktonic
• Some benthic
– Accumulations can produce diatomaceous earth and chert
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Protista
• Calcareous Nannoplankton– Small spherical cells
– Armored• overlapping plates of
calcium carbonate
– Mostly marine plankton
• Accumulations can produce chalk
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Protista
• Multi-cellular algae– Much drifts
– Some attaches to seafloor
• Some red and green algae secrete calcium carbonate skeletons– limestone
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Protista
• Protozoans with skeletons– Foraminifera
• Chambered skeleton of calcium carbonate
• Very abundant
• Useful for dating rocks and sediments
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Protista
• Protozoa with skeletons
• Radiolarians– Skeleton made out of
opal (SiO2)
– Related to foraminifera
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Fungi
• Decomposers– Obtain nutrients from dead organisms
• Diverse– Yeast– Mushroom
• Poor fossil record
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Plants
• Differ from multicellular green algae– Internal fertilization of egg– Tissue
• Vascular– Vessels for transport of
water, dissolved nutrients, food
• Non-vascular– Transportation of materials
by diffusion• moss
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Plants
• Seedless Vascular Plants – Evolved first
– Psilotum• Simplest vascular plant
• No leaves or roots
• Similar to earliest fossil forms
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• Ferns– Roots and leaves
– Alternation of generations• Spore-producing then sperm-
producing generation
– Spores• One set of chromosomes
• Fertilized by sperm
• Requires moisture
– Vast Late Paleozoic swamps led to coal formation
Plants
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Plants
• Gymnosperms– “Naked seed” plants
– Conifers• Cone-bearing plants
• Eggs are fertilized in cone by pollen– Pollen bears sperm; carried by wind
• Dominant in the Mesozoic
• Angiosperms– Flowering plants
• Pollen carried by pollinators (animals)
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Animals
• Two groups– Vertebrates
• Possess a backbone
– Invertebrates
• Coelom– Body cavity housing internal
organs
• Protostomes– First opening becomes the
mouth
• Deuterostomes– First opening becomes the
anus
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Animals
• Sponges– Simple invertebrates
– Suspension feeds• Strain particles from water
• Mostly eat bacteria
• Flagella pump water through internal canals
– Calcium carbonate or silica spicules support structure
• Cambrian - modern
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Cnidarians
• Jellyfish and corals
• Radial symmetry
• Inner and outer body layer– Jelly-like layer in between
• Use tentacles to catch prey– Stinging cells
• Sexual and asexual reproduction
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Protostome Invertebrate
• Segmented worms– Fluid-filled coelom
• Primitive skeleton
– Each segment has own coelomic cavity
• Expand, contract for movement
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Arthropods
• Insects, crabs, spiders, lobsters, trilobites
• Trilobite– Three-lobed body
• Central, left-and right- lobed
– External skeleton– Gill-like structure for
respiration– Legs– Primitive eyes
• Common in Cambrian
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Arthropods
• Crustaceans– Head of five fused segments
– Thorax and abdomen
– Weakly calcified exoskeleton
• Insects– Head, thorax, abdomen
– Two pairs of wings
– Poor fossil record
– Precede angiosperms
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Arthropods
• Onychophorans– Intermediate between
segmented worms and arthropods
– Early forms• Marine
• Nearly to base of Paleozoic
– Modern forms• terrestrial
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Mollusks
• Clams, snails, octopuses– Shell of aragonite, calcite,
or both
– Mantle• Fleshy, sheetlike organ
• Secretes shell
– Radula• File-like structure for food
– Base of Cambrian
• Monoplacophorans– Primitive mollusks
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Mollusks
• Gastropods– Snails
– Marine and freshwater
– Terrestrial• Lung
– Most grazers• Some suspension
feeders
– Beginning of Paleozoic
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Mollusks
• Cephalopods– Squids, octopuses,
chambered nautiluses– Swim in the sea
• Jet propulsion• Eyes
– Carnivores• Catch with tentacles• Eat with strong beak
• Chambered nautilus– Buoyancy due to gas in shell
• Common in Phanerozoic
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Mollusks
• Clams, mussels, oysters, scallops– Shell divided into two valves– No head or radula– Muscles pull shell together– Suspension feeders mostly
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Lophophores
• Brachiopods– Shell divided into two
valves– Lampshells– Lophophores
• Pump water• Strain food
– Inarticular brachiopods• Lack hinge teeth• Lingula
– Articulate brachiopods
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Bryozoans
• Moss animals• Colonial• Closely related to
brachiopods– Lophophore extended
from skeleton to feed
– Calcified skeleton
• Ordovician
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Echinoderms
• Spiny-skinned form• Five-fold symmetry
– Starfishes• Predators• Lower Paleozoic
– Sea urchins• Regular sea urchins
– Radially symmetrical bodies
• Irregular sea urchins– Bilaterally symmetric– Burrowers
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Echinoderms
• Crinoids– Sea lilies
– Sieve food using arms• Pass food to mouth with
tube feet
– May swim
– May be attached by flexible stalk
– Disk-shaped plates from stalk
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Chordates
• Notochord– Flexible, rodlike structure
• Runs length of body• Supports body
– For some part of lifecycle
– Spinal cord• Runs next to notochord
• Primitive Chordate– Lancet
• Notochord is skeleton• Can swim• Usually rests
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Vertebrates
• Notochord develops into vertebral column– Usually bony
– Cartilage in sharks
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Conodonts
• “Cone-teeth”– Originally thought to
be teeth of a marine animal
• Later determined to be eel-like fish and a vertebrate
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Vertebrates
• Fishes– Ray-finned fishes
• Fins supported by thin bones radiating from body
– Lobe-finned fishes• Evolved into amphibians• Coelacanth
– Discovered in 1939
• Amphibians– First to live on land as
adults– Metamorphosis
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Vertebrates
• Reptiles– Eggs with protective
shells– Ectothermic
• Environment controls internal body temperature
• Dinosaurs• Birds
– Endothermic
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Vertebrates
• Mammals– Endothermic; Hair– Bear live young– Montreme
• Lay eggs
– Marsupial• Offspring develop in
pouch
– Placental
• Therapsids– Ancestral mammals– Arose in Mesozoic
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