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Chapter 3
The Diversity of Life
1
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?
2
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
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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-/underrepresented)
• 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.
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Putative Jellyfish fossils
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The Current Hotspot
American/Mongolian team excavating an ankylosaur fossil in the Gobi Desert in Mongolia.
13
Buy Fossils Now!
• eBay http://www.ebay.com
• http://www.arizonaskiesmeteorites.com/Din
osaur_Fossils_For_Sale/
14
Taxonomy
15
Human Genealogy
(Who else is hanging
around in your
family tree?)
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Taxonomic Scheme
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Kingdom
Phylum
Class
Order
Family
Genus
Species
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Taxonomic Scheme
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Karl
Plays
Cards
Only
For
Green
Stamps
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Taxonomic Scheme
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Kids
Prefer
Candy
Over
Fat
Gooey
Snails
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Taxonomic Scheme
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Kingdom
Phyum
Sub-phylum
Class
Order
Family
Genus
Species
- Animal
- Chordate
- Vertebrate
- Mammal
- Primate
- Hominid
- Homo
- Homo sapiens
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More Mnemonics
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Animalia
Chordata
Vertebrata
Mammalia
Primata
Hominid
Homo
Homo sapiens
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Ana
Caught
Vince
Making
Piping
Hot
Ham
Sandwiches
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Animalia
Chordata
Vertebrata
Mammalia
Primata
Hominid
Homo
Homo sapiens
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A
chocolate
valentine
may
produce
hot and
heavy
sweethearts
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Animalia
Chordata
Vertebrata
Mammalia
Primata
Hominid
Homo
Homo sapiens
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A
crystal
vase
might
possibly
hold
hybrid
sunflowers
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Animalia
Chordata
Vertebrata
Mammalia
Primata
Hominid
Homo
Homo sapiens
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Amy
cutout
valentines for
Ma,
Pa,
her
husband and
sister
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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
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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
36
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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Plants
• Ferns
– Roots and leaves
– Alternation of generations
• Spore-producing then spermproducing generation
– Spores
• One set of chromosomes
• Fertilized by sperm
• Requires moisture
– Vast Late Paleozoic swamps
led to coal formation
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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 rightlobed
– 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
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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
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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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