Formation of the Earth • Earth was formed

approx. 4.54 billion years ago out of the solar nebula.

• Initially molten, the outer layer cooled to form a crust about 4.3 B.Y.A. as water was brought to Earth by meteors.

• By 3.9 B.Y.A. Earth had cooled enough to form oceans.

Formation of the Earth • Out gassing and volcanic activity produced the primordial

atmosphere consisting of water vapor, carbon dioxide, hydrogen, ammonia, methane, and other gasses.

• The primordial ocean was most likely made up of water, with methane, ammonia, hydrogen, sulfur, and carbon dioxide.

• No free oxygen in the atmosphere or oceans at this time.

First Life on Earth• Life – metabolism and reproduction, growth and

response to stimuli (adaptation).• Proto-cells: cell-like spheroid formed from

proteinoids (chained groups of amino acids).– Proto-cells containing RNA may have been the first

cellular life forms on Earth. (3.8 B.Y.A.)

The First Cells• Prokaryotic cells: Cells without a membrane-

bound nucleus. (3.5 - 2.5 B.Y.A.)– First autotrophs, blue-green algae. (supplied the

first oxygen to the atmosphere)– Genetic material is in a circular loop called a

plasmid

The First Cells• Eukaryotic cells: cells with a membrane-enclosed

nucleus.– Developed approx. 2 billion years ago– Include all complex cells and make up all multi-cellular

organisms.• Animals, plants, fungi, and protists are eukaryotes.

Precambrian• Proterozoic Eon – 2500 to 543 mya– Paleoproterozoic Era – 2500 to 1600 mya• Stable continents• 2400 – 2100: Huronian ice age

– Mesoproterozoic Era – 1600 to 900 mya• Formation of supercontinent Rodinia• Eukaryotic cells appear• 1200 mya: spore/gamete formation (sexual reproduction)• Photosynthetic organisms proliferate, oxygen above 10%• Formation of the ozone layer • 950 mya: start of Stuartian-Varangian ice age

Precambrian• Proterozoic Eon – 2500 to 543 mya– Neoproterozoic Era – 900 to 643 mya• Earth day is 18 hours long• Formation of a supercontinent Pangea

– Cryogenian Period – 850 to 635 mya• 750 mya: End of last magnetic reversal• 650 mya: mass extinction of 70% of dominant sea plants.

Phanerozoic Eon 543 mya to present• Paleozoic Era – 543 to 251 mya– Vendian (Ediacaran) Period – 635 to 543 mya• 570 mya: end of Stuartian-Varangian ice age• Soft-bodied organisms developed, first jellyfish

– Cambrian Period – 543 to 490 mya• Most of the major groups of animals first appear.• 530 mya: Animals with shells appeared.

Phanerozoic Eon • Paleozoic Era – 543 to 251 mya– Ordovician Period – 490 to 443 mya

• Diverse marine invertebrates, first vertebrates appear, first green plants and fungi on land

• 450 mya: start of Andean-Saharan ice age• 443 mya mass extinction of many marine invertebrates.

– Silurian Period – 433 to 417 mya• End of Adean-Saharan ice age, stabilization of Earth’s climate• Coral reefs appeared, first fish with jaws, spiders, centipedes and

plants appear on land.

Phanerozoic Eon 543 mya to present• Paleozoic Era – 543 to 251 mya– Devonian Period – 417 to 354 mya• Ferns and seed-bearing plants appeared, first amphibians• Wingless insects and vertebrates appear on land• Pannotia fragmented into Laurasia and Gondwana• Atmospheric oxygen level about 16%• 374 mya: mass extinction of 70% of marine species

Phanerozoic Eon 543 mya to present

• Paleozoic Era – 543 to 251 mya– Carboniferous Period – 354 to 299 mya• Mississippian Epoch – 354 to 318 mya

– Karoo ice age, large primitive trees, vertebrates appear on land, first winged insects

• Pennsylvanian Epoch – 318 to 299 mya– First reptiles, atmospheric oxygen over 30%, giant arthropods, deposits

of coal form in Europe and Asia.

Phanerozoic Eon 543 mya to present

• Paleozoic Era – 543 to 251 mya– Permian Period – 299 to 251 mya• Formation of the supercontinent Pangaea, Earth is cold and dry• Conifers appear• 260 mya: end of Karoo ice age• Oxygen levels drop from 30% to 12%• 251 mya: Great Permian-Triassic mass extinction – 90% of

ocean dwellers and 70% of land plants and animals.

Phanerozoic Eon 543 mya to present

• Mesozoic Era – 251 to 65 mya– Triassic Period – 251 to 200 mya• Breakup of Pangea• First dinosaurs appear, first evidence of mammals• 201 mya: mass extinction 20% of marine animals

Phanerozoic Eon 543 mya to present

• Mesozoic Era – 251 to 65 mya– Jurassic Period – 200 to 145 mya• Earth is warm – no polar ice• Age of the dinosaurs: giant herbivores and vicious carnivores.• North America splits from Europe.• 150 mya: First birds (archaeopteryx) appear

Phanerozoic Eon 543 mya to present• Mesozoic Era – 251 to 65 mya– Cretaceous Period – 145 to 65 mya• Africa and India split from Antarctica, South America splits

from Africa• Flowering plants, crocodiles appear, modern mammals and

birds developed.• 70 mya: T-Rex thrived• 65 mya: Meteor impact, Yucatan, Mexico – mass extinction of

dinosaurs.

Phanerozoic Eon 543 mya to present

• Cenozoic Era – 65 mya to today– Tertiary period – 65to 1.8 mya• Paleocene Epoch – 65 to 54.8 mya– Appearance of placental animals– Formation of Rocky Mtns, major global

warming

Eocene Epoch – 54.8 to 33.7 myaIndia and Asia collide

forming the Himalayas, Australia separates from Antarctica.

Small modern mammals appear.

Phanerozoic Eon • Cenozoic Era – 65 mya to today– Tertiary period – 65 to 1.8 mya• Oligocene Epoch – 33.7 to 23.8 mya– Start of Pleistocene ice age– Appearance of grasses, elephants, camels, early horses.

• Miocene Epoch – 23.8 to 5.3 mya– The plants and animals of the Miocene were fairly modern. –Mammals and birds were well-established. Whales, seals,

and kelp spread.

Phanerozoic Eon 543 mya to present

• Cenozoic Era – 65 mya to today– Tertiary period – 65to 1.8 mya• Pliocene Epoch – 5.3 to 1.8 mya– Accumulation of ice at the poles– Spread of grasslands, rise of long-legged grazing animals– 2.4 mya: Homo habilis appears, tool making humanoids

Phanerozoic Eon • Cenozoic Era – 65 mya to today–Quaternary Period – 1.8 mya to today• Pleistocene Epoch – 1.8 mya to 10,000 yrs ago

– Homo erectus moves out of Africa– Presence of large land mammals and birds– Global cooling and glaciation– Neanderthals – 500,000 yrs ago– Homo sapiens – 200,000 yrs ago

Phanerozoic Eon • Cenozoic Era – 65 mya to today– Quaternary Period – 1.8 mya to today• Holocene Epoch – 11,600ya to today– Development of agriculture and

domestication of animals.– 9,000 ya: metal smelting– 5,500 ya: wheel– 5,000 ya: writing– 4,500 ya: Pyramids– 2,000 ya: Christian Era– 250 ya: industrialization– 50 ya: Space Travel