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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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