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History of Life

What is Life Anyway?

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What is Life Anyway?

• A definition of life– Metabolizing– Replicating– Contained in a cell membrane

• Closed chemical system– Components

• Protein• Nucleic acids – RNA, DNA• Organic phosphorus

– light to cell energy

Life in a Bottle?

• Stanley Miller’s Jar– Methane– Ammonia– Hydrogen– Water – Electrical charge

• Red turbid liquid with amino acids and some other components of life.

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Life in a Bottle?

• Many later similar experiments– “the same amino acids that form most easily

in laboratory experiments are the most common in living things today”

• Condition = No Oxygen!• Recent findings – Black smokers

The Precambrian and The Origin of Life

• The Eoarchean 4.6 (+?)-3.6 billion years– Oldest detrital zircon = 4.4 billion years before present– Oldest rocks 3.8 and 3.96 billion

• What happened?– Earth accreted from planetesimals– Earth differentiated into core, mantle, and crust– Earth bombarded by comets and meteorites– Volcanic activity ubiquitous– Atmosphere formed

• Hydrosphere began

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Volcanoes emit the gases that form the atmosphere

Water from volcanoesAnd from cometsCondenses to form Oceans

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First Life?

Black Smokers

Monera

First Photosynthetic lifeCyanobacteria

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Cyanobacteria in Rocks

OncolitesDevonian

StromatolitesPrecambrian

Stromatolites

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Ediacara Biota

The Ediacara (pronounced /�iːdi�ækərə/, formerly Vendian)

biota consisted of enigmatic tubular and frond-shaped sessile

(stationary) organisms which lived during the Ediacaran Period (ca.

635-542 Ma). Trace fossils of these organisms have been found

worldwide, and represent the earliest known complex multicellular organisms.

Dickinsonia costata

Ediacara biota

Charniodiscus

Tateana inflata

Charnia

Spriggina

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Ediacara biota

Trace fossil Trace fossils?

Other Ediacarans

Possible predator

Acritarch

Kimberella

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Shelly Faunas

Acritarchs

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Cambrian Explosion 570-500MYA

• Virtually all phyla of importance appear and leave a record in hard parts.

• Significance of hard parts:– Allows visible life – was it already there?– Response to predation– Allows animals to grow larger– Allows more control of functions– Allows takeover of new niches

Trilobites Rule!

Lower and Middle Cambrian Trilobites

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The Burgess Shale

• Middle Cambrian• Preservation of soft

parts• Not far off the floor• Many relatives of

the arthropods• Many unknown

phyla• High diversity and

disparity

Burgess Shale Fauna

Opabinia Marrella

2 species of Anomalocaris

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Cambrian MicrofossilsForaminifera

AcritarchsRadiolaria

Conodonts

Ostracods

ORDOVICIAN 500-430MYA

• Second half of the Age of Invertebrates

• Trilobites are still abundant• First corals, crinoids,

bryozoans, bivalves• First primitive fishes• First spores of land plants

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ORDOVICIAN

Crinoid and bryozoan

Bryozoans and Brachiopods

ORDOVICIAN

Articulate Brachiopod

Coral encrusting gastropod

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Ordovician Microfossils

Agglutinated ForaminiferaRadiolaria

ChitonozoaAcritarchsOstracods

SILURIAN 430-395MYA

• First Land Life– Psilophye plants (vascular)– Scorpionlike animals similar to Euripterids

• Trilobites decrease• Reef corals• Cephalopods• Jawed fish

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SILURIAN

CooksoniaEarly plant

Silurian fish

RECONSTRUCTION OF SEA FLOOR

SILURIAN

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Silurian Microfossils

Radiolaria

Dinoflagellate

ForaminiferaAcritarchs

Chitinozoa

Land Plant spores ?

DEVONIAN 395-345 MYA

• The Age of Fishes –salt and fresh water– Early sharks– Early bony fish

• First insects• First forests

(evergreens)• First amphibians

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DEVONIAN

Mainly giant ferns

DEVONIAN

PhacopsDev. Trilobite

Devonian reef life

fish

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Devonian Microfossils

Chitinozoans

ConodontsAcritarchsAggultinated ForaminiferaRadiolaria

Land Plant Spores

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MISSISSIPPIAN 345-320MYA

• Beginning of the Age of Amphibians• Beginning of the Carboniferous (coal

bearing strata)

MISSISSIPPIAN

Fish

Nautiloid

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MISSISSIPPIAN

Coal Swamp

Mississippian microfossils

Calcareous Foraminifera

RadiolariaAcritarchsChitonozoansOstradods

Bisaccate Pollen

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PENNSYLVANIAN 320-280 MYA

• Part 2 of the age of amphibians (diverse)

• Coal-forming swamps peak in abundance

• Large winged insects

• First reptiles• N. America under

vast inland seas

PENNSYLVANIAN

Swamp forest of the Pennsylvanian

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PENNSYLVANIAN

Hylonomus early reptile

Diplovertebron 1.5m amphibian

Meganeura 70cm winged insect

Pennsylvanian Microfossils

Fusulinids

Calc. foramsRadsPollenConodontsOstracods

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PERMIAN 280-245 MYA

• Part 3 of Age of Amphibians (reptiles present)

• Trilobites wane • Cycads and true conifers appear• Pangea

PERMIAN

Dimetrodon and Eryops

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PERMIAN

Ocher Fauna

PERMIAN

Titanophoneous

Edaphosaurus

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PERMIAN

Permian Microfossils

Fusilinids

Radiolaria

Calcareous ForaminiferaConodontsPollen and SporesOstracods

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PERMIAN-TRIASSIC EXTINCTION EVENT 248MYA

• Extinction of 96% of species in the marine realm.– Trilobites extinct– Rugose and tabulate corals extinct– Fusulinid Foraminifera

• Extinction of 75% of land vertebrates

TRIASSIC 248-208 MYA• Beginning of the Age of

Reptiles• Gymnosperms dominate

plants• Reptiles dominate the land• First dinosaurs and turtles• First mammals• First flying vertebrates

(Pterosaurs)• Bivalves and Gastropods

dominate the marine benthic fauna

• Hexacorals appear• Dinoflagellates diversify

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TRIASSIC

Proterosuchus early Triassic reptile

TRIASSIC

Labyrinthodont

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Triassic Microfossils

Dinoflagellate

Calcareous nannoplankton

ForaminiferaRadiolariaPollen and spores

JURASSIC 208-144 mya

• Part 2 of Age of Reptiles• Ammonites diversified• Coral reefs similar to modern• Giant dinosaurs ruled land• Giant marine reptiles• Earliest birds• Crabs and lobsters

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JURASSIC

JURASSIC

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Jurassic Microfossils

DinoflagellatesPlanktonic Foraminifera

CRETACEOUS 144-66 MYA

• Part 3 of the Age of Reptiles• Ammonites diversify• Dinosaurs flourish• First Angiosperms (flowering plants)

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CRETACEOUS

CRETAC EOUS

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Cretaceous Microfossils

Angiospermpollen Dinoflagellates

Diatoms

Planktonic and benthonic foraminiferaRadiolaria

K/T BOUNDARY EXTINCTION EVENT

• Dinosaurs extinct• Ammonites extinct• Large marine reptiles extinct• Plankton affected• Land plants affected

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TERTIARY 66-1.6 MYA

• Mammals diversify and become large• Birds flourish• First primates, first monkeys and apes• Primitive to intermediate horses and

camels• First grasses• First whales• Earliest homonid fossils

TERTIARY INVERTEBRATES

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TERTIARY BIRDS

Diatryma giant bird 2 meters tall

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PALEOCENE MAMMALS

1. Prodictus, an early carnivore; 2. insectivores; 3. 19 cm long Ptilodus; I4. 1m high Pantolanbda

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Scene from the Eocene

Restoration of Fossils from Eocene John Day Formation in Oregon. 1. titanotherestanding 2.5m tall; 2. carnivores ; 3. ancient horses; 4. tapirs; 5. rhinoceros

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Hyracotherium“Dawn horse”

Phenacodus

Moropus, an extinct genus of the chalicotheres (ungulates with claws instead of hooves) related to the horse. Fossil remains are found in Miocene deposits of North America and Asia.

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TERTIARY HORSE

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PLIOCENE MAMMALS OF WESTERN NORTH AMERICA

Tertiary Microfossils

Numulites .25 in across

Diatoms

Microscopic Foraminifera

DinoflagellatesSilicaflagellatesPollen and spores

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QUATERNARY 1.6-PRESENT

• Homo erectus and other homonids

• Homo sapiens• Many large mammals

rise and become extinct• Ice Ages

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Quaternary

Smilodon californicus saber tooth catDire Wolf

QUATERNARY

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QUATERNARY

Giant Ground Sloth

QUATERNARY

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Wonderful Life!