"We will now discuss in a little more detail the Struggle for Existence." Darwin
The Precambrian
Stand still you ever-moving spheres of heaven,
That time may cease, and midnight never come.
--Christopher Marlowe (1564 - 1593)
(This period makes up approximately 7/8ths of the Earth's history!)
Prior to 3.8 billion years ago - Hadrean Era
Protoplanetary diskElements are added to the planet
The Solar System and Earth are born from a churning nebula of dust and gas and heavy elements derived from an earlier supernova in the galactic neighbourhood. When the sun ignited a violent shock hurled most of the stellar debris into deep space. Proplyds, containing organic molecules, condense even further to form the planetary system surrounding our star. The sun was cooler, radiating 25% less energy than today.
3.8 to 2.5 billion years ago - Archean Era
stromatolite
The rate of heat production by the breakdown of radioactive isotopes was several times greater than today, but eventually, the Earth's crust begins to cool and attains some stability and rigidity. Crust building activity such as volcanoes begin to form bits of continental rock. The earth is spinning faster upon its axis. Oceans are forming, condensing from atmospheric vapour.
Organic compounds called lipids exist in seabeds. Organic information processing has begun and blue-green algae and bacteria evolve. The first primitive cells were of the Prokaryotic type and probably obtained energy through the splitting of simple available organic compounds. Filamentous and spheroidal microfossils are found in many Precambrian sediments. Prokaryotic cell organisms, incapable of cell division, are small, ca 10 microns, and have no cell nucleus.
The first cells were probably primitive bacterial and algal heterotrophs; that is they fed off energy from organic compounds (not the atmospheric carbon dioxide). These cells diversified and became autotrophs, or cells able to utilize energy from atmospheric carbon dioxide and water. Cyanobacteria grow in colonies large enough to see and in some places they formed stromatolites. They are aquatic and photosynthetic.
Organisms which feed off the carbon dioxide in the atmosphere begin to release oxygen into the atmosphere and ocean. This triggers a change in the chemistry of the ocean and atmosphere from a carbon dioxide-rich mixture eventually to the present-day oxygen-rich atmosphere.
Proterozoic rocks become important sources of metallic ores, notably of iron, gold, copper, uranium, and nickel.
Regional impacting continues.(?) 1x100,000 years = 27,000 1km impacts in 2.7 billion years
Some polar glaciation.
The Moon has become geologically inactive.
2.5 billion to 544 million years ago - Proterozoic Era
The moon is receding from the planet. It will separate nearly 100,000 kms in the next billion years.
The diversity of simple marine organisms. Stromatalites become important as the first reefs.
1.4 billion years ago Eukaryotic cell organisms develop, either by an infolding of the cell wall to form internal structures or by an invasion of smaller specialized procaryotes which then form the internal structure of the eukaryote cell. This promotes greater genetic variation and faster evolution. Eukaryotes take over as the dominant life form. The atmosphere is increasingly oxygenic yet still only 1% of oxygen levels in the modern era.
1.1 billion years ago, Rodinia, the first stable supercontinent forms then 750 million years ago Rodinia breaks into three pieces
1.0 billion years ago begins the greatest glaciation period the Earth has ever experienced. About 650 million years ago 70% of the dominant Precambrian flora and fauna perished in the first great extinction.
600 million years ago The continental pieces of Rondinia come back together in a big crunch known as the Pan-African orogeny (mountain building event). The new supercontinent is known as Pannotia.
The first multi-celled animals (metazoa) evolved, types of jellyfish and worms without skeletons or shells. In an area now known as the Ediacara Hills of South Australia an assortment of sea animals had evolved highly differentiated systems of muscles, nerve cells and food-gathering and sexual organs. Fossils of similar life forms have also been found in Canada and Africa. Some members of the Ediacara biota survived the extinction and become the ancestors of the life forms which evolve during the next era. Ediacara
Earthshine
Cambrian
Burgess Shale, Hallucinagenia ... locomotion plus.545 million years ago "Cambrian Explosion." All life is still in water but begins to proliferate and diversify. Animals with hard shells and backbones skeletons) appear in marine environments. Skeletons serve as an adaptive breakthrough, support for muscles, protection against environment and predators, and aid in locomotion, allowing preferential survival and niche exploitation. Trilobites andsome mollusks appear in great numbers. Trilobites made up 80% of animal species. Animals with eyes first appear.
Trilobite
550 million years ago Pannotia breaks up into several small fragments, Laurentia (the core of the modern era North America), Baltica (Northern Europe), and Siberia and one large piece (now China, India, Africa, South America and Antarctica) known as Gondwana. Atmospheric oxygen levels are 10% of modern era levels.
515 million years ago Burgess Shale fauna is alive, these may have been the first animals to use body colour to repel predators. Pikaia evolves, the world's first known chordate, possibly the ancestor of all other vertebrates.
Pikaia of the Burgess Shale
Four mass extinctions occurred during the course of the Cambrian.
Snowball Earth?
The two most accepted current hypotheses for the Cambrian extinction are: glaciation in the early Ordovician and cooling and depletion of oxygen in marine waters.
Ordovician
505 - 438 million years ago
A crinoid is not a plant, but an animal that learned to plant its feet on the seafloor.
From the Early to Middle Ordovician, the earth experienced a milder climate in which the weather was warm and the atmosphere contained a lot of moisture. In the seas rugose and tabulate forms of coral reefs evolved and a variety of new types of life, including cephalopods, bryozoans, crinoids, graptolites, gastropods, and bivalves flourished. Life begins grasping outward for its food. Ordovician communities displayed a higher ecological complexity than Cambrian communities due to the greater diversity of organisms. The diversity of sea animal genera may have increased due to active mountain building activity when more nutrients and environmental isolation fueled development of species, tectonic activity contributing to life's energy needs. On land types of algae and fungus begin to evolve.
Ordovician sea
Ordovician Mass extinction - 440 - 450 million years ago was the second greatest mass extinction of marine life in the history of Earth, caused the disappearance of one third of all brachiopod and bryozoan families, as well as numerous groups of conodonts, trilobites, and graptolites. Much of the reef-building fauna was also decimated. In total, more than one hundred families of marine invertebrates perished in this extinction.
Silurian
438 - 408 million years ago
Silurian crinoids
Some of the Rodinian mass is torn apart and moved to equatorial regions. The remains of Rodinia, Gondwana, rotated clockwise and moved northward to collide with Laurasia --
Baltica and the attached micro continent Avalonia begin colliding with North America in scissors fashion [north to south] to form the Caledonian-Acadian orogeny.
Silurian Map
Rise in sea levels due to polar glacier melts. Estuaries became more productive and diverse, while freshwater habitats were being colonized. Rapid spread of jawless fish and first land animals that feed on terrestrial algae and fungus.
Pterygolepis - Anaspida
Devonian
408 - 360 million years ago
Age of a transforming biosphere.
The bony fishes of the seas diversified and the world was dominated by reef builders such as the stromatoporoids, and corals, and some of the world's largest reef complexes were built. Early Devonian saw freshwater branchiopods appear in streams. The variety of land plants increased dramatically and the first land animals appear. Tracheophyta, vascular plants, evolved along water's edge supporting a greater diversity of invertebrates like spiders and scorpions. At mid-Devonian the first jawed fish appear and the first forests arose. By the Late Devonian, plants were sufficiently evolved to colonize drier land and the early tetrapods walked the Earth.
Hynerpeton - early tetrapod
Appalachian mountains form.
Atmospheric oxygen reaches modern era levels.
Late Devonian Mass Extinction at the Frasnian - Famennian boundary. Evidence supporting an episode of global cooling suggests that warm water marine species were the most severely affected when sea levels lowered triggered by a glaciation event on Gondwana.
Moresnetia zalesskyi fossil of late Devonian Hans Steur
Archaeognatha wingless insect of the Devonian by Wayne P. Maddison
Gosslingia breconensis fossil of early Devonian
Carboniferous
360 - 286 million years ago
Carboniferous forest
The forests were composed of giant club mosses, tree ferns, and horsetails, some of which towered more than 30m (99ft) above the forest floor. The most abundant of the modern era coal supplies accumulated by the respiration of these forests.
The first reptiles evolve. Westlothiana, a tiny creature, contains many intermediate characters between primitive tetrapods and true
amniotes. The amniotic egg allowed Synapsida and Sauropsida the ancestors of birds and mammals, to breed away from water, opening up vast new environments for habitation. Insects were evolving such as the dragonflies with 71cm (28in) wingspans, and cockroaches over 10cm (4in) long. In the rivers and in the seas, the jawed, bony fish had largely replaced the jawless, heavily armored fish.
Westlothiana
Permian
286 - 245 million years ago
functional types of amniote skulls
Two ancestral amniotes flourished, the Sauropsida, reptiles lie the labyrinthodonts and future dinosaurs and Synapsida which includes pelycosaurs like the "finback" dimetrodon and future mammals.
The continental islands move together to form the massive landmass of Pangea. Ocean currents moderate temperate coastal areas, and the continental interior is dry. Prolonged volcanism forms the terrace-like formations known as the Siberian Traps. The effects of the massive eruption would have made the world dark and increased sulfur dioxide, cooling the planet, then producing carbon-dioxide in the atmosphere, heating the planet. The seas regressed. Permian extinction brings an end to 95% of all ocean-dwelling species and at least 70% of land-dwelling vertebrates. Bye, bye trilobytes. The cause of the Permian extinction was either an asteroid or comet impact big enough to crack the Earth's crust causing the prolonged volcanism at the Siberian Traps. Questions whether impacts cause volcanic events are just now being answered.
Dimetrodon - mammilian ancestor
LENGTH: 250 centimeters (8 feet) HEIGHT: 90-120centimeters (3-4 feet) WEIGHT: 70 kilograms (150 pounds) DIET: Other animals
The Mesozoic
286 - 245 million years ago - The Triassic
The continental mass was warm, but cut off from rain-bearing ocean winds, inland regions formed vast deserts.
Extreme volcanism and tectonic activity along the western coast of North America results in the building of the western cordillera. In the seas ammonoids have replaced the trilobites of the Permian. In the early Triassic they are characterized by subdued shell ornamentation but by the end of the period the shells become more decorative. Marine animals flourished in the warm, tropical oceans, in particular the ammonoids, brachiopods, and echinoderms.
In the seas ammonoids have replaced the trilobites of the Permian. In the early Triassic they are characterized by subdued shell ornamentation but by the end of the period the shells become more decorative. Marine animals flourished in the warm, tropical oceans, in particular the ammonoids, brachiopods, and echinoderms.
Dicynodont
A mammal-like reptile
Ferns and horsetail plants grew near water, tree-like cycadeoids and cycads were the tallest plants. Ginkoes and swamp cypress had evolved. Conifers evolved in upland dry areas. For most of this period the dominant land animal is a mammal-like reptile, aquatic, herbivorous therapsids, like the Dicynodonts. Their posture was sprawling and their size was from one to three meters in length.
Dinosaurs begin to evolve from the most quadrupedal reptiles, thecodonts. In the late Triassic the first known predatory dinosaurs are the Staruikosaurids, the Herrerasurids and the Coelophysids. Mouse-like prototherian mammals appear.
A thecodont,
forerunner of the dinosaurs
A volcanic crisis at the end of the Triassic period heats up the planet and delivers basalt lavas across a 7 million km area. Pangea (All Earth) begins to break up into Laurasia (North America, Europe, and Asia) and Gondwana (South America, Africa, India, Antarctica and Australia.)
208 - 150 million years ago - The Jurassic
The rifting of the supercontinents continue. The Atlantic Ocean opens and shallow seas covered much of North America. Climates were warm and wet.
The primitive dinosaurs which survived the extinctions at the end of the Triassic begin a 130 million year dominance of the planet. Evolutionary innovation and complexity provide lifeforms with new technologies; getting upright and taking the skull of an animal above ground level, ie: HerraRaptor. Eventually, the evolution of the dinosaur would produce a diversity of hundreds of species, many who socialized in communities.
It is the age of the size counts. Great plant-eating sauropods and predatory theropods get bigger. The oceans are full of fish, squid, and coiled ammonites, plus great ichthyosaurs and long-necked plesiosaurs.
Pterosaur
Pterosaurs, the first flyers, are thought to be derived from a bipedal, cursorial (running) archosaur in the late Triassic period. Primitive mammals, marsupials, and cranes have evolved. Flowering plants begin to appear as do butterflies.
149 - 65 million years ago - The Cretaceous
Temperatures on Earth were warm. Flora and fauna thrived around polar regions as well as the equator. The land was covered with forests and a large inland sea divided the North American Continent.
40 ft, 10 ton reptilian sea monster, Mosasaur were the largest marine predator.
mosasaur
A collision between a cosmic rock and the moon 110 mya forms Copernicus Crater.
Deccan basalts in India may have played a role in the extinction of the dinosaurs. Most of the basalt erupted between 65 and 60 million years ago.
gravity map of the chicxulub impact
The last day of the Mesozoic. Chixilub KT impact. Oblique @30% 6 km/sec 10-15 km mass=? Comet or Asteroid? Impact energy would be 1000 times greater than exploding all of the human nuclear weapons all at once. Much of the impact energy was transferred to the atmosphere and a sudden poisonous haze cooled the planet 3 - 7 degrees. Immense acid rain fell onto the land and ocean shutting down photosynthesis. A sudden a but short darkening of the skies caused the extinction of 7 out of 10 species. Rule of the Reptile Ends.
Over the next era, the planet would warm again and spores would colonize a decimated low diversity environment. The small mammals, terrabirds, some aquatic life, and insects were the only survivors able to adapt to the new environment.Earth and Moon from Apollo 11
The Cenozoic
65 million years ago ... life pervades again - Tertiary
Fragmentation of continental landmasses continue. Rifts separated Africa from South America and then Australia from Antarctica. Gondwanaland ceases to exist as a supercontinent. The Atlantic Ocean widens. Africa moved northward towards Eurasia, closing the Tethys Ocean and raising the Alps. India collides with Asia, forming the Himalayan mountains. Australia rifts free of what is left of Gondwanaland and becomes an Island Continent drifting northwards towards Asia.
Sea-levels fall and expose dry land in much of inland North America, Africa, and Australia. South America has separated becoming an island with its own unique evolution of animals.
At the beginning of this era the world was almost devoid of large terrestrial animals. There wasn't an animal larger than 30 kgs, all with small brain cavities, and archaic features. However, it was only 10 million years before large animals were roaming the continents taking up the ecological niches left vacant by the extinction of the dinosaurs.
Mesonychia, from hooved animals
Mesonychia, derived from hoofed mammals, were the first group of mammals to become meat eaters, they were the likely dominant land predators of the paleocene epoch.
49 million years ago
Kamensk meteorite impact, Russia, results in a crater 25 kms in diameter.
40 million years ago
Azuara meteorite impact, Spain, results in a crater 30 kms in diameter.
38 million years ago
The continents arrive their present positions.
Mistastin meteorite impact, east coast of North America, results in a crater 28 kms in diameter.
35 million years ago
Chesapeake Bay meteorite impact, east coast of North America, results in a crater 85 kms in diameter. Popigai meteorite impact, Russia, results in a crater 100 kms in diameter.
25 million years ago
Logancha meteorite impact, Russia, results in a crater 20 kms in diameter.
20 million years ago
Haughton meteorite impact, in the Canadian north, results in a crater 24 kms in diameter.
Chimapanzee
15 million years ago
Ries meteorite impact, in Europe, results in a crater 24 kms in diameter.
10 million years ago
Last common ancestor of hominids and apes. Ramapithecus, once thought to be a human ancestor had evolved, different from apes mainly in skull innovations, but some evidence suggests that Ramapithecus is related closer to orangutans than humans.
5 million years ago
Kara-Kul meteorite impact, Tajikistan, results in a crater 52 kms in diameter.
4.4 million years ago
Ardipithecus ramidus, a forest dweller, four foot tall bipedal.
3.5 million years ago
Lucy walks the Earth (Australopithecus afarensis).
1 million years ago
500,000 years ago
Archaic forms of Homo sapiens first appear.
250,000 years ago
Neanderthals appeared in Europe.
200,000 years ago
Homo Sapiens come out of Africa and may have interbred with Neanderthals
50,000 years ago
Impact in Arizona forms Meteor Crater
20,000 years ago
Neanderthals disappear.
Homo sapiens paint star maps on the Altimera cave walls in France.
10,000 years ago
Last great ice age. When the planet's northern polar cap extended over northern Europe, the moist Mediterranean air was pushed into equatorial regions by a dominant high-pressure system over the icy cap. The climate of the Nile, and Tigris and Eurphrates became considerably more comfortable for human habitation than it is today. Modern human civilization begins.
6,000 years ago
Writing is developed in Sumeria.
4,000 years ago
A massive earthquake in Sodom and Gohmorrah. Hebrews suspect it is the retribution of God. It is also the age of Noah's flood when according to scripture the Earth became a less habitable place. Mammoths become extinct, but for their frozen remains.
200 years ago
The planet's human population reaches one billion.
140 years ago
Darwin's "Origin of Species" Debate in England. Age of the Earth controversies reaches a fevered pitch.
100 years ago
Tunguska impact
Coates and Marsh uncover 125 species of dinosaurs
50 years ago
Neil Armstrong and Buzz Aldrin walk on the moon.
Voyager 1 & 2 are launched on missions of Solar System Exploration
1999
Chandra X-Ray Observatory
Chandra Xray Observatory is launched.
