The "Earth is quite a charmed planet. . . . Earth as a cradle of life can be seen in its prehistory, its origins, its chemical composition, and its early evolution. . . . Earth is actually the final product of an elaborate sequence of events that occurred over the span of 15 billion years, three times the age of the Earth itself. . . . a formidable task."
Peter D. Ward & Donald Brownlee, Rare Earth, p. 36-37.
The fossils from the walls of the Grand Canyon account for rock formations that are between 2 billion and 600 million years old. They reveal frequent examples of adaptive
radiation of life from the sea, to the air, and onto dry land. Large sections
of the fossil record are missing from the canyon's rock walls. These limestone walls suggest the importance of the ocean in fostering life on earth; the fossils found
in these canyon rocks reveal a startling puzzle. These pieces of the geological puzzle that we see are from distinctly different ages of the land, because strikingly divergent body plans found in these fossils indicate numerous successive changes in the terrains over the long-term, or deep geological past. The Colorado River has cut down through the planet's history to reveal numberless lost world's of fantastic variety.
The great divisions in the
"rocks of ages" record both subtle and enormous changes based on the
shifting dominance of marine, to vegetable, and eventually terrestrial fossils.
Along the right there is a listing of the most recent to the oldest or earliest periods from fossil evidence drawn with respect to the relative temperatures that are revealed by that fossil data, during those vast periods of geological time.
********1** These prolonged extinction
events shaped the kinds of dominant species and their descendants on Earth in subsequent periods such that surviving groups of creatures could adaptively radiate throughout the world in particulalrly sustaining conditions favorable to their needs.
The species we see today
–contributing to the biological diversity, biogeography, and ecological puzzle pieces– are experiencing another worldwide extinction; in part induced
by the spread of human settlements, agriculture & industry.
variability of surface and ocean temperatures in the deep past is revealed in the graph. The right side of the graph indicates colder prevailing temperatures while the left side shows warmer periods. This long stability of the warm period in the Cambrian when so many varied body forms of both radially and bilaterally symmetrical organisms are discoverable in the fossil record are examples of how widespread the diversity of life had become during the what is called a "Cambrian explosion."
4.6 – 3.8 billion, gradual formation
of the planet Earth from space debris and interstellar gas.
PRIMAL
ATMOSPHERE;
consisted of very hot nitrogen, methane,
ammonia, carbon and sulfur dioxides, with no free oxygen.
"About 4.5 billion years ago, Earth began to differentiate into different layers." molten iron-nickel core, molten mantle, thin crust of enormous heat.
"The length of the day was shorter, . . . .The sun was much dimmer, . . . . a poisonous, turbulent atmosphere composed of carbon dioxide, hydrogen sulfide, steam, and methane. . . . .only traces of oxygen. . . . The sky itself might have been orange to brick-red in color, and the seas,, which surely covered all of the planet's surface . . . , would have been muddy brown and clogged with sediment."
4.3 billion, The Earth's surface cooled as scattered ponds coalesced
into larger water bodies from either outgassing of water from volcanoes or the interception of icy meteorites striking the molten iron-rich surface.
4.1 billion,
Oceans formed
worldwide from either
out-gassing of the mantle or
comet & asteroid collisions with the earth.
ARCHEON
4 billion years ago: Oceans fully developed in physical size and chemical composition covering the surface in thousands of feet of water; potentially as deep as 4000 meters.1
3.96 billion, oldest known
rocks on Earth
RNA world is one with the widespread existence of a replicant molecule that makes copies of itself stringing together adenine, guanine, cytosine, and uracil.
adenine, adenosine are strings of nitrogen bases (nucleic acids) that form amino-acids; these chains of amino acids aligned and then folded into proteins, and these specific proteins act as the drivers of metabolism and life.
Slowing of a long-durational bombardment of the Earth by asteroids, comets & meteorites; days wereGreenland Shield's oldest
rocks suggest simple
bacterial, moneran organisms
3.5 billion "abundant organisms capable of responding to light and able to build mounds existed . . .in rocks from the Warrawoona region of Australia."
3.2 billion, further evidence for
an origin of life in the form of bacterial lines of life that feed off of volcanic sulfur and surface methane.
√ – proto-cells fossilized that are
PROCARYOTIC
MONERAN
CELLS
having spread in extensive oceans.
3 billion
Nsuze Palesol the name of an archaic soil from Africa; "three-billion-year-old soils from South Africa shows that oxygen appeared in the atmosphere more than 600 million years earlier than previously thought, . . ."
Rising oxygen levels were an inadvertently beneficial outcome of bacterial activity.
PRO–PALEOPHYTIC
3 billion, Literally:
older plants; figuratively called
the dawning of the earliest plants.
Plants, algae and some bacteria are those essential creatures with the capacity to use solar radiation in order
to nourish themselves, maintain body parts and function to reproduce. Their
waste product – oxygen – eventually transformed the Earth's older atmosphere
into the present oxygen rich air.
Aerobic PROCARYOTIC
CELLS – meaning simple, small cells with poorly developed nuclei are evident.
PROTEROZOIC
2.5 billion, Cyanobacteria are dominant reef builders form oldest Canadian Shield rocks of the SLAVE
PROVINCE
2.4 billion, Rift valley forms in the Slave and Bear provinces
2.3 billion, Stromatolite
Reefs form of blue-green bacterial layered colonies having formed mats in shallow coastal seas.
2.2 billion, Oldest glacial
evidence for an early ice-age.
Reversal of the Slave and
Bear continental movement due to the oceanic rift; Slave continent is rammed into the Churchill province along
McDonald fault (Canada)
is evidence of plate
tectonics; the movement of–otherwise apparently stationary pieces of–the
earth's crust by the motion of hot magmas (or lava) in the mantle beneath the
planet's rocky surface.
1.7 billion,
The Oldest of the Grand Canyon's numerous metamorphic and limestone formations.
1 billion,
SEXUAL
REPRODUCTION
MANIFEST in the
PHANEROZOIC
1,0000 million-700 million years ago Rodinia a supercontinent existed.
√ – the supercontinent of Rodinia made up of US and Canada with Euro-Africa-Asia around it created a huge desert. Little to no water was readily available meaning extensive arid conditions spread.
An earlier supercontinent –persisted for 350 million years– has been given the name Rodinia,;"a Russian word meaning 'homeland,' formed from a mass continental collision blocked the warm water currents that flowed previously to the poles and a prolonged ice age began, ice advanced and covered the earth, plunging temperatures to – 40? {minus 40 degrees F} and affecting most if not all species of living creatures. During this period when so many land-masses congealed cyanobacteria dominated the planet's oceans, ultraviolet radiation permeated the air, and there was no evidence of life on land."
Rocks of the Okanogan Highlands are nearly a billion years old,"Geologists have named these rocks the “Belt Supergroup” after a small town in Montana. The Belt rocks are multicolored sandstone, siltstone and limestone noted for their beautiful preservation of sedimentary features such as mud cracks, ripple marks and abundant 'stromatolites' –cabbage shaped fossils left by the action of cyanobacteria.”
" . . . some 750 million years ago, the end of Rodinia began in what is now east-central Washington.
There exists substantial & convincing "evidence that ice extended to near equatorial latitudes in the late Precambrian, about 700 million years ago. . . . all of the oceans may have been covered with ice to considerable depths . . . . These extremely cold temperatures would have had an enormous influence on the surface of our planet. For example, continental weathering would have slowed or stopped . . . . From space Earth would have looked white and brown–the white being the ice covers on the oceans, the brown the denuded land areas. . . . The oceans would have begun to accumulate with metal ions, mainly iron and manganese. For as long as 30 million years, the glaciers and ice never relaxed their frigid grip . . ."
free oxygen at 1% of the
current ambient level in the atmosphere, due to the photosynthesis ability of
blue-green bacteria.
"Escape from this 'icehouse' { glaciers and ice never relaxed } condition was only accomplished by the buildup of volcanic gases, particularly carbon dioxide, mostly from undersea volcanic activity. Deglaciation during the end of these glacial events must have been spectacular, with nearly 30 million years of carbon dioxide, ferrous iron, and long-buried nutrients suddenly being exposed to fresh air and sunlight."
Such marine seas are where calcium in the
water reacts with carbon to form a milky dispersion called calcium
carbonate which is heavy enough to settle at the bottom of a watery
pool if the winds do not stir up the bottom sediments and the pH is such that calcium carbonate hardens and settles on the quiet sea bottom.
680
million years old,
Some of the oldest animal fossils had lived and fed on the shallow floor of the Iapetus seas of the Panthalassic Ocean.
Precambrian
670 million, jellyfish
fossil, blue-green bacterial reef forming organisms flourish in warm shallow
seas, called stromatolites.
About 650 million years ago, seventy percent of the dominant Precambrian flora and fauna perished in the first great extinction.
600 million,
Ural Mountains rise from the collision
of Europe with Siberia,TRILOBITES
numerous;
From the Oxford University natural history museum an example of the variety of trilobites from the Precambrian seas of the Panthalassic ocean.
Oxford University Museum of Natural History.Siry, July 2006.
550 million, chitin shelled
creatures emerge (same exoskeleton as insects).
AVALONIAN OROGENY ends in the creation of a micro-continent;
It as called Avalonia (right) as a series of terrains (an island arc) that form the rocks now found in the mountains of Great Britain, Newfoundland, Canada and eastern New York state
and New England, suggesting that these now separate mountain chains were once a single chain like the Andes.
"Rhode Island and the New England states were not the only land masses to emerge from the Avalonian arc. In the sketch above, J marks the approximate location of Jamestown, Rhode Island. EW indicates the portion of Avalonia that became southern Ireland, England and Wales, Ib shows Iberia (Spain and Portugal) and Ar Armorica and Bohemia. A portion of the arc is now part of Morocco. Future parts of Nova Scotia, New Brunswick and Newfoundland, as well as most of New England are offshore from Florida (labeled F on the map at right). The portion of the arc that became part of the Carolinas is to the right of Jamestown, offshore of what is now Venezuela, in South America."
An explosion (Cambrian seas) of water plants and marine animals. In terms of the variety of ancestral populations we still can identify living now. Below is a diagram of taxonomic groups still extant today from this earlier archaic period and found in the fossil records.
Cambrian
545 million, – extensive
oceans cover North America ( N. A. is red on the map to the right.) warm shallow seas persist worldwide.
An explosion of shallow
marine organisms with greater varieties of body plans (invertebrates) than are
now living or currently extant.
540 million, lampreys as one mere example of a representative animal family of
"all of the animal phyla (the categories of animal life characterized by unique body plans, such as arthropods, mollusks, and chordates)" which "either evolved or first appear in the fossil record. . . . animals are both diverse and abundant in 500 million year-old rocks, and they include representatives of most animal phyla still found on Earth. . . . The rate of evolutionary innovation and new species formation during the Cambrian Explosion has never been equalled."
Marine arthropod called Anomalocaris (at left and below from Burgess shale fossils) is a seaside predator of some immense size and speculated ferocity. It fed in waters where salt water algae, sponges,
brachiopods, cnidarians, mollusks, trilobites, crustaceans, starfish, and stromatolite
reef building species spread in the warm tropical seas.
This predator was a large creature feeding on bottom dwelling denizens, or animals classified by where they live and are called called benthic fauna. Anomalocaris was a free swimming animal, unlike the corals and anemones.
A far greater diversity of animal body forms existed in this period, than now, since the evidence in the Burgess shale (Canada) formations is extensive:
530 m. y. a. –– TheBURGESS
SHALE FORMATION:
"By recognizing so many unique anatomies in the Burgess, and by showing that familiar groups were then experimenting with designs so far beyond the modern range, they have inverted the" way we think about the diversity of life on earth. "The sweep of anatomical variety reached a maximum right after the initial diversification of multi-cellular animal. The later history of life proceeded by elimination, not expansion. The current earth may hold more species than ever before, but most are iterations on a few basic body plans."
"Compared with the Burgess seas, today's oceans contain many more species based upon many fewer anatomical plans."
"The maximum range of anatomical possibilities arises with the first rush of diversification. Later history is a tale of restriction, as most of the early experiments succumb and life settles down to generating endless variants upon a few surviving models. "
Well over
half of North America covered by ocean water. There exists "evidence of continental glaciation at the Cambrian-Ordovician boundary is responsible for a decrease in global climatic conditions. Such a decline in temperature is implied by Miller" to have destroyed the existing "Cambrian fauna which are intolerant of cooler conditions, producing a mass extinction of mostly warm water species." This cooling led to oxygen depletion of the waters and a mass mortality of marine creatures
505 million, early shelled
(calcium carbonate) organisms such as Anomalocaris and fishes.
500 million, early mountain
building (Orogeny) in Eastern N. A.
Cephalopods like the chambered
nautilus' ancestors called ammonites are varied and dominant. The earliest vertebrates are extensively preserved in limestone
dominant rock (slate and marble sources). Huge deposits of once living creatures form oil and gas deposits associated with the rocks of the Cincinnati
Arch; Tapeats Sandstone and Bright Angel formations of Grand Canyon.
Silurian
Appearance of the first land
arthropods and land plants.
438 million,
early vascular plants, ancestral
mosses and liverworts. The club-mosses' ancestors' called LYCOPSIDS emerged as the largest land forested genera expanding in the Carboniferous forests–the source of modern coal.
The northern APPALACHIAN MOUNTAINS
formed from the collision of two continents:
1) Laurentia and
2) Baltica
collided during the
TACONIC
OROGENY, evidence in New York State of the suturing of the two continents that coincided with teh closing of the Iapetus seas.
Estuarine animals become significantly more plentiful and diverse in the Middle and Late Silurian. In addition, they’re more clearly differentiated from contemporary marine assemblages. The extinct Eurypterids, but extant Horseshoe crab fossils or Polyphemus (right photograph) are evidence of a diversifying arthropod (joint legged-exoskeletal creatures) populations.
Coelacanths and other jaw less
fishes emerged, the earliest evergreen forests began to dominate the land. In these seas there were sharks and "A Devonian tetrapod-like fish..." from the middle Devonian 375 million years ago marking the slow transition to land of these sea-dwellers.
"The first trees on earth. Its name was Archeopteris, and along rivers it grew sixty feet high, a tall conifer shaft with these fronds hanging from its branches, overshadowing the life below. . . . the fruiting bodies of the Archeopteris and leaves . . . scattered among the Archeopteris were minnow-sized fishes, irredescent lung-fishes teeth, scales of armored, placoderm fish." A.
The planet's land masses were divided into Gondwanaland in the south and Laurasia in the north divided by the shallow circum-equatorial water body called the proto-Thethys Sea.
Life in the Devonian sea was quite diverse including giant eurypterids or 'sea scorpions' pursued early jawed fishes, including acanthodians (sometimes called 'spiny sharks', though not related to true sharks) and shield-headed fishes called placoderms (which probably shared a common ancestor with the sharks).
Rugose and other corals built great reefs, providing food and living spaces for many different kinds of creature.
The sea floor supported a rich variety of crinoid 'sea lilies', stalked clam-like animals called brachiopods, bizarre colonial critters known as graptolites, and early versions of mollusks - such as chitons, tusk shells, and straight-shelled cephalopods related to modern-day nautiloids.
The first plants - small, leafy pioneers known as reunifies - colonized the land, followed shortly thereafter by joint-limbed creatures such as scorpions, centipedes, and millipedes.
400
million years ago:
fishes dominate seas; early
amphibians spread; vascular plants: club mosses, horsetails, Gymnosperms, seed
ferns and other green plants are common.
375 million,
Mangrove swamps, fish on
mud flats, ACADIAN
OROGENY
formation of a Appalachian/ Pennine/ Scandinavian single mountain chain stretching
along the equator.
The tetrapod called Tiktaalik–a fossil of a predatory "four-footed" fish with the head of a crocodile revealing the sort of link between land dwelling animals and their fish cousins. "Tiktaalik lived,..." on "a landmass that straddled the equator and had a subtropical climate." See the Fish-tetrapod transition, NSF.
"a remarkable new fossil species that represents the most compelling evidence yet of an intermediate stage between fish and early limbed animals."
"The skeletal structure of Tiktaalik and the nature of the deposits where it was found suggest an animal that lived on the water bottom, in the shallows, and perhaps even out of the water for short periods.
"The skeleton of Tiktaalik indicates that it could support its body under the force of gravity whether in very shallow water or on land," said Farish Jenkins of Harvard University. "This represents a critical early phase in the evolution of all limbed animals, including us."
The tropical warmth fostered huge forests defining this coal forming age persisted due to extensive swamps and favorably wet climate conditions over Eurasia and North America.
Artist's rendering of the carboniferous forest based on fossil evidence.
Lycopsids: "These trees dominated the lowland swamps of the Upper Carboniferous and contributed most of the organic matter to the vast coal deposits that extend over much of North America and Eurasia." See "The Devonian Times" and especially the Lycopsid pages.
A number of Carboniferous arachnids somewhat resembled spiders, and in fact appeared at about the same time as the first true spiders. Like spiders, they were terrestrial and respired through book lungs, and walked on eight legs. However, they were not true spiders, nor necessarily ancestral to them, but represented independent offshoots of the Arachnida. Trigonotarbids are currently the oldest known land arthropods.
Most of these fossils of the oldest known land arthropods are found in the Upper Carboniferous (Pennsylvanian), though they have also been found in the Ludlow Lane fauna of England (Pridolian, late Silurian), the Alken an der Mosel fauna of Germany (Emsian, early Devonian) the Rhynie Chert of Scotland (Siegenian, early Devonian) and the Gilboa, New York fauna from the Panther Mountain formation (Givetian, middle Devonian). Not much is known about their relationships. [See: U. C. Berkeley, Museum of Paleontology].
Mississippian
380 million, Antler Orogeny was the "first major tectonic event to affect the passive margin that transected" Northeastern Nevada and Western Utah.
"The Antler orogeny occurred in Mississippian time at a passive margin of the sialic North American continent in Nevada and probably in Idaho." see: Speed and Sleep "Antler orogeny and foreland basin..." in Geological –GSA:Bulletin– Society of America.
360 million, modern ancestors of the "naked seed" plants we call Gymnosperms;
cycads, conifers and gingkos are widely evident in the fossils.
These plants were food for the earliest amphibians and reptiles that emerged
in vast warm, moist (tropical) swamps.
Huge horsetails
(equisetum, a descendent pictured at left) coexist with giant dragon flies tree-like progymnosperms such as the Archaeopteris and lycopsids.
Horseshoe crab ancestors – relatives of spiders and scorpions – are increasingly numerous in the fossil record and they possess blue or copper bearing (not iron as in hemoglobin) blood.
345 million, large amounts of vegetation
that have become fossilized leading to coal formations worldwide.
Oceans increase in volume worldwide.
325 million,
GONDWANALAND (a vast southern continent made of Africa, South America, Antarctic, Australia and India) separates
from Euro-Asian-N. American continent.
Pennsylvanian Sea invades Southwestern North America creating warm tropical seas beside extensive swamp and flood lands.
Pennsylvanian
320 million, beetles
and dragon flies thrive in luxuriant swamps, tropical inland seas. Nevada
is an ocean bed.
300 million, Tree ferns
and lush forests dominated by the scale tree or Lepidodendron characterize
widespread swamps that formed the basis of today's coal deposits in America,
Europe, South Africa and Russia.
Southern APPALACHIAN MOUNTAINS
formed from collision with AFRICA;
INSECTS,
SNAILS,
earliest REPTILES found.
Permian
286 million,
Appalachian
Mountains attain the
size of today's Rocky Mountains or European Alps as the super continent Pangaea or Pangea formed, vast wind-blown deserts cover north America and Dimetrodon dinosaurs spread.
Ice sheets form in the
southern portions of Pangean super continent.
240 million years ago crocodiles & alligators separated from dinosaurs .
245 million, Permian
Extinction: half of the known families of animals and plants, both terrestrial
and marine, perished!
"Some 252 million years ago, the Permian-Triassic mass extinction wiped out an estimated nine of every ten species on the planet—scientists call this one “the Great Dying.”
Scientific American, Lee Billings, "Fact or Fiction?: Dark Matter Killed the Dinosaurs
A new out-of-this-world theory links mass extinctions with exotic astrophysics and galactic architecture," March 25, 2015
235 million, renewed warming
allows stromatolites, coralline algae & bryozoans begin to form reef communities
after a long,10 million year hiatus.
Emiliania huxleyi played an expanding role in Earth's climate through both coccolith formation and gas emission. Crocodiles and alligators survived the Permian Extinction.
The late Triassic world as revealed in the Palisades Orogeny was characterized by the start of the break-up of a great continent of Pangaea, straddling the equator, depicted on this map of the globe at that time. Globe of the later Triassic showing locations of the oceans and Pangaea.
This is the period in which the ancestors of today's turtles & tortoises arose taking advantage of the warm waters and warm seas of the great Panthallasic Ocean and the Tethys Ocean stretching under the Earth's equatorial sun.
214 million years ago the Manicouagan impact crater formed [65 kilometers (40 miles) in diameter] in what is now Quebec, Canada.
144 million, the end of a reptilian age of Dinosaurs and Pterosaurs.
A very extensive equatorial
shallow ocean called Tethys Sea forms connecting the Atlantic, Pacific and Indian
ocean basins leaving only 18% of the Earth as dry land, as a circum-equatorial and hence warm water system redistributing heat around the planet.
Spread of gymnosperms
& angiosperms.
During the Cretaceous "Florida was a shallow submarine limestone bank."
132-130 million, The Brandberg Massif or Brandberg Intrusion in central Namibia: a graniticintrusion forms a dome-shaped massif today, originated during Early Cretaceousrifting that led to the opening of the South Atlantic ocean.
120 million, unfadingly hot climate prevails.
100 million, placental
mammals appear and as birds spread worldwide.
77 million, an abandoned nest of egg-laying therapod–a small meat-eating dinosaur–from Alberta.
75 million, fossil from Alberta sands a complete nest of turtle eggs recovered. First "fossil of a pregnant turtle found" of a species of river turtle called Adocus.See *
66.4 million, Cretaceous
extinction of once very widespread and diverse dinosaurs, trilobites, and ammonites is the largest mass die-off in terms of diverse forms of life since the Permian time.
Modern period of animals indicative of large predators and herds of herbivores on the prairies of Eurasia, including
India, Africa and the South American Pampas, the North American Great Plains are slowly drying creating arid grasslands.
Paleocene
65 million, the long collision of
India with Eurasia begins.
The horse descent illustration below is from recent to oldest at the bottom:
Eocene
57.8 million, early primates,
giant birds, formation of grasslands in Eurasia, Africa and the Americas due to mountain building,
The Hyracotherium or early horses, so called "eohippus," in the fossil record.
50 million, earliest Sirenians in the circum-global, Tethys Sea.
40 million, extinction of "part of a very large group of species called the baenid turtles," due it is thought to the drying out or desertification of North America. The group was river dwelling consuming soft, aquatic plants and crustaceans.
36.6 million, the San Andreas Fault system of California starts to gradually take shape in the middle Tertiary time (beginning about 28 million years ago). The gradual movement on the fault system since that time is about 282 miles stretching from the Gulf of California to
Cape Mendocino and dividing the
state into two opposite moving plates along a seismically active transform fault boundary.
The slow closing of the Tethys Sea that equatorially connected the world's oceans.
Miocene
23.7 million, extensive
marine intrusion in California, Florida, the Mississippi Valley, and Texas, called a marinetransgression; monkey-like primates
emerge.
Northern Australia reaches its present tropical position and the Great Barrier
reef begins forming. A circum-equatorial sea girdles the earth creating a warmer dispersal of tropical waters to the poles and connecting the oceans along the equator.
Volcanic rocks in the Hollister of Central California region are roughly 12 million years old.
Whereas the volcanic rocks in the Sonoma-Clear Lake region north of San Francisco Bay range from only few million to as little as 10,000 years old.
Both of these volcanic areas and older volcanic rocks in the north bay region are offset by the modern regional fault system that has been active since the formation of those rock assemblies.
(Image modified after original illustration by Irwin, 1990 and Stoffer, 2006.).
The convergence of these oceanic plates with the western edge of the North American plate profoundly influenced volcanic and igneous activity west of and including Colorado, and caused mountain building (orogenesis) in the same region.
When two plates converged (sutured) or come together; the remnants can still be seen in the far western US.
10 million, Aegyptopithecene
Apes thrive in northern Africa.
divergence of apes (Chimpanzees, Orangutans, & Gorillas) and hominid lines.
Equatorial Africa is well forested with little of the savannah that exists today.
6 million, Orrorin tugenensis in Kenya's rift valley, earliest human ancestor.
Orrorin tugenensis, a.k.a. the "Original man" from Tugen Hills, Kenya evidence for bipedalism at 6 million years ago!
5.3 million, Antarctica
rafted to its current polar position generating conditions for glaciers and
ice sheets to form augmenting planetary cooling and a lowering of sea levels
worldwide.
4.4 million, Ardipithecus ramidus in east Africa ( "the root of humankind" - in the native Ethiopian language. ). Note by Dr. Dennis O'neil Palomar College: "Ardipithecus ramidus is currently the best candidate for being the immediate ancestors of the australopithecines."
3 million, the closing of the circum-equatorial sea by a rise of land along the Isthmus of Panama, further elevation of the Himalayan plateau, and growth of permanent ice sheets in Antarctica.
genus Homo coexistent with Australopithecus, East Africa.
3 to 2 million, begins a million year survival of South Africa's A. africanus.
2.5 million, Australopithecus garhi - was recovered between 1996 and 1998 from the Middle Awash, Ethiopia, evidence of lithic, or stone culture and of food processing (two characteristicsnormally attributed to the genus Homo).
Late Pliocene
2 million,
A series of
Ice Ages and interglacial retreats commences. As ice accumulates the sea
level declines; as glaciers melt during inter-glacial warming periods, the sea level rises. Consequent changes in the rainfall and temperature patterns triggered the retreat of extensive tropical forests in favor of more open grassland-savannah terrains where arid adjusted plants thrived.
Prehistoric sea level
varies from 400 feet lower to 50 feet higher than today.
1.6 million The Solo River's site of Ngandong fossils reveal the arrival on Java, Indonesia of Homo erectus, where populations "apparently lived in 'splendid isolation' without competition from any other human species."
There is disagreement on the exact age of these Ngandong fossil-bed remains, much later Middle Pleistocene.
1–1.5 million Homo erectus —one human ancestor— evidence for these people as earliest "fire-users."
1 million year old remains of human fossils near Zhoukoudian, China (northern plain)
Sequences of Ice Ages persist with intermittent interglacial warming periods. Evidence of humans in Spain from eight fossil specimens among the oldest hominin from Europe ever recovered; Australian Museum.
Findings of a totally modern human facial morphology from "Gran Dolina (Sierra de Atapuerca, Spain)"Journal of Human Evolution, Pub/Med; 1999, Academic Press.
500,000Homo heidelbergensis believed to have migrated out of Africa into Europe.
250,000
Homo neanderthalensis (persistent effects of Neanderthal DNA on modern human Eurasian populations: {Physics News; \ Science 12 Feb 2016.}) For age of Neanderthal populations in Asia and Europe 400,000 -28,000 years ago (Smithsonian).
200,000 earliest modern human, or Homo sapiens, emerge in East Africa.
100,000 "modern humans began to spread out of Africa to begin the eventual colonization of the rest of the world." Bryan Sykes, Seven Daughters of Eve, p. 277.
Homo erectus skull
Mount Tobaa volcano at the northern part of the Indonesian island of Sumatra erupted 74,000 years ago among the largest volcanic eruptions in Earth's history.
50,000 Neanderthal peoples in
La Ferrassie, France
36,000 – 25,000 Interglacial retreat
of ice, cave paintings [shown at right]
in Lascaux, France and Altamira, Spain (22,000 years ago).
20,000 Ice Age (Würm or
Wisconsin) resumes with ice sheets in Britain and Scandinavia and equivalent
ice in New England and the Great Lakes.
15,000 Interglacial Warming
trend resumes, mountain glaciers retreat and sea level rises; sometimes abruptly rising sea-level erodes coastal sediments and drowns settlements.
7,000 Cities at Jericho,
Israel and Catal Hüyuk, Anatolia. Rapid melting of glaciers (Deglaciation) causes sea levels to rise and the great drying-out of the extensive grasslands (desertification) for thousands of years begins.
Primary sites of plant and animal domestication in prehistory.
Allegedly humans contribute
to a warmer atmosphere as they adopt farming practices in eight to eleven areas around
the world exposing populations to new diseases and a revolution in diet.
The known areas were:
Mesopotamia
China, northern Yellow
River and southern Yangtze River.
Roy E. Hunt, "A brief Geological History of North America," table A.2. Geotechnical investigation methods: a field guide for geotechnical engineers. p. 327.
A.
Zimmer, Carl. At the Water's Edge: Fish with fingers, Whales with Legs, and How Life Came Ashore but Then Went back to Sea. New York: Simon & Schuster, 1998. p. 42-43. Descriptions of the Devonian tetrapod environs of early North America.
Eon [aeon] is a length of geological time equal to a billion years, Eras are subdivisions of eons and Periods are subdivisions of eras; periods are further subdivided into epochs, while epochs are subdivided into ages. Pliocene Epoch of the Cenozoic Era.
Eventful Periods in
Hominins diverge from primates after
earliest primates emerged (Lemurids)
marine mammals return to the sea
oldest mammals
Amniotes diverge from Amphibians
oldest vertebrates
An older version of geologic time or "deep" time scale; chronological chart.
Like tree rings that reveal the age of centuries-old cedar, growth rings in Indian Ocean coral tell how El Niño, the warm-water phenomenon of the tropical Pacific Ocean, influences marine temperatures a continent away.
"We found a record of climate change that reflected the influence of the tropical Pacific (El Niño) on [the Indian Ocean]. This record tells us a story that has broad climate
implications," said Julia Cole of the University of Arizona and co-author of a report on
coral growth rings. "ENSO (El Niño/Southern Oscillation) has a very long reach. El Niño
brings more rain to East Africa just as it does to Arizona, but it also warms the oceans
there."
Reliable records of sea temperatures in the western Indian Ocean date back only a few
decades, and scientists have been hard-pressed to decipher the long-term influence of El Niño on these temperatures. Coral rings are filling in the gaps.
"Climate data from this part of the world is limited," said Cole. "But coral can grow for
centuries. We know that El Niño affects the inter-annual climate, which is the variability
from year to year. El Niño also has a long-term cycle and we found that decadal variations
of El Niño drive decadal variability in the Indian Ocean. People have never looked at the
decadal variability and attributed it to the Pacific Ocean and El Niño."
Studying temperature records together with coral growth rings, the researchers discovered a correlation between El Niño in the tropical Pacific and higher
surface temperatures in the Indian Ocean. El Niño, they conclude, has a greater effect than Asian and African monsoons on sea-surface temperatures in the
Indian Ocean.
"Our study indicates that in addition to being responsible for some of the year-to-year changes in East African climate, ENSO may also set the pace for slower
decadal changes," said Cole.
ENSO refers to oceanic and atmospheric fluctuations that originate in the tropical Pacific and affect climate in various areas across the globe.
"Only when we have a long-term perspective can we say anything at all about long-term variability, especially decadal variability," said Cole.
The study provides clues to the role oceans play in the grand global climate scheme. It will also help
forecasters better predict the weather.
"One new piece of information the long-term perspective gives us is that the temperature in the region over
the last decade was warmer than during the past two centuries," said Cole. "There are not many records of
actual ocean temperatures, so adding ocean measurements to the pool, that's one more piece of
information that makes a strong case something unusual is going on."
The unusual occurrence is global warming.
"When there's a long record of climate, like the one from the coral, we can ask the question of whether
recent warm conditions are unusual or part of a natural cycle," said Cole. "What we found is just one of
many cycles that show warming is not part of the natural cycle.
The scientists didn't directly study the effects of El Niño's warm water on the coral. But they note that
when seawater gets unusually warm, coral suffers.
"Many corals die when sea temperature exceeds 31 degrees centigrade (94 degrees Fahrenheit)," said Tim
McClanahan of the Wildlife Conservation Society and a member of the research team. "The effects of El Niño have killed many of the corals in the western Indian Ocean, despite being far from the center of the
El Niño phenomenon. Our study shows that we can expect more warming and coral mortality in the
future, which is making local and national management of reefs difficult."
The researchers studied a resilient, abundant coral off the coast of Kenya with growth rings dating back to
1801. They found this living thermometer, called Porites lutea, about 20 feet underwater near Malindi
Marine Park. They drilled a small core through the 12-foot-tall coral and assessed the colony.
Chemical changes in the rings tell the story of sea temperature. When the water is warm, the coral reveals
light oxygen. When the water is cold, the coral is saturated with heavy oxygen. [See isotopes].
"We cored up and down the Kenya coast, from the Tanzanian border to Malindi," said Cole. "We had the
advantage of local ecologists on the project with us, and they helped us find the best sites."
Cole, McClanahan, Robert Dunbar of Stanford University and Nyawira Muthiga of the Kenya Wildlife
Service collaborated on the report, which was published in the Jan. 28 issue of Science.
Copyright 2000, Environmental News Network,All Rights Reserved.
" . . . some 750 million years ago, the end of Rodinia began in what is now east-central Washington. 
now found in the mountains of Great Britain, Newfoundland, Canada and eastern New York state
and New England, suggesting that these now separate mountain chains were once a single chain like the Andes.
 430.JPG)
Marine arthropod called Anomalocaris (at left and below from 
Anomalocaris and fishes.
Devonian
jawed fishes, including acanthodians (sometimes called 'spiny sharks', though not related to true sharks) and shield-headed fishes called placoderms (which probably shared a common ancestor with the sharks). 
Northeastern Nevada and Western Utah. 
Huge horsetails
(equisetum, a descendent pictured at left) coexist with giant dragon flies tree-like 
Nevada
is an ocean bed. 
Volcanic rocks in the Hollister of Central California region are roughly 12 million years old.
5.5 million, 
"dawn of human ancestry"
*
500,000 Homo heidelbergensis believed to have migrated out of Africa into Europe. 
