1: Introduction

Age of the universe: billion years Age of the solar system: 4.6 billion years Age of earth: 4.5 billion years Age of life: 3.5 billion years Age of eukaryotes: 1.8 billion years Age of multicellulars: 900 million years Age of chordates: 500 million years Age of mammals: 240 million years Age of primates: 60 million years Age of apes: 30 million years Age of genus Homo: 2.5 million years Age of Homo sapiens: 100,000 years Written history: ~5,000 years

Hadean solar system oldest known rock (possibly with organic carbon) nothing was living during the Hadean earth bacteria eukaryotes multicellular organisms chordates end of dinosaurs

The very beginning: millions years ago (mya). The period between the creation of the solar system, and our time is divided in two: (1)Precambrian Time (4.5 to 543 mya). (2)Phanerozoic Eon (543 mya to present).

Hadean time: 4.5 to 3.8 billion years ago. This is not a geological period as such. No rocks on the Earth are this old - except for meteorites. During Hadean time, the Solar System was forming, probably within a large cloud of gas and dust around the sun. Oldest stones: zircon crystal 4.4 billion years

The boundary between the two eons (Hadean and Archaean) is defined because rocks appeared and with them - fossils Hadean oldest known rock (possibly with organic carbon)

Archaean time 3.8 to 2.5 billion years ago The atmosphere was reducing, composed of methane, ammonia, and other gases which would be toxic to most life on our planet today. Earth's crust cooled down enough that rocks and continental plates began to form.

It was early in the Archaean that life first appeared on Earth. Our oldest fossils date back to roughly 3.5 billion years ago, and consist of bacteria microfossils. In fact, all life forms during the more than one billion years of the Archaean were bacterial. Spheroids representing bacteria microfossils (1.8 to 3 billion years ago). Hoyt Lakes Mine (USA). These microfossils are found within Banded Iron Formation (BIF).

Spherical objects, identified as microfossils and named Isuasphaera isua (Pflug), were reported in 1978 from Greenland stones Ga old. However the nature of these objects is questioned. gigaannum, usual symbol Ga, is a unit of time equal to 10 9 years.

Extensive banded iron formations (BIF's) on the western shores of Lake Superior, indicate that photosynthesis was occurring and oxygen was being produced

Modern stromatolites Australia stromatolites Pre-cambrian stromatolites Australia 1.6 billion years old Pre-cambrian stromatolites South Africa 3.5 Ga

The boundary between the two eons (Archaean and Proterozoic) is defines because oxygen appeared Hadean

With the beginning of the Middle Proterozoic comes the first evidence of oxygen build-up in the atmosphere. This global catastrophe spelled doom for many bacterial groups, but made possible the explosion of eukaryotic forms. These include multicellular algae, and toward the end of the Proterozoic, the first animals. Proterozoic = the O 2 pollution

Proterozoic Era: The first Eukaryotes ( Ga) The exact origin of eukaryotes is unknown. But few signs allow to differentiate Eukaryotes fossils from bacteria The size of the cell. The presence of tetrades (4 cells together) Grypania spiralis was a coiled, spaghetti-like organism up to half a meter in length found in ~1.3 Ga shales from Montana, China, and India. Shales = צפחה

Proterozoic Era: The first Eukaryotes ( Ga) The exact origin of eukaryotes is unknown. But few signs allow to differentiate Eukaryotes fossils from bacteria The size of the cell. The presence of tetrads (4 cells together) Tetrad: ~ Ma China.

A widely distributed group of soft-bodied marine organisms (First discovered in 1868 but only seriously considered in 1957 !) Proterozoic Era: the first animals (635 to 542 Ma) Dickinsonia (south Australia and north Russia)

Cyclomedusa radiata, (Australia) Proterozoic Era: the first animals (635 to 542 Ma)

Proterozoic Era: the first multicellular algae Doushantuophyton Ma China.

The boundary between the two eons (Proterozoic and Phanerozoic) is defined because animal fossils appeared Hadean The presence of fossils in the “Primordial Strata” was noted as early as the mid 19th century

Hadean Phanerozoic Cambrian explosion

The Cambrian explosion ( MYA) Almost every metazoan phylum with hard parts, and many that lack hard parts, made its first appearance in the Cambrian.

Anomalocaris: A giant predator of the Cambrian (some specimens grew up to 2 metres)

Hallucigenia: wormlike 0.5 to 3 cm-long animal.

Hadean Phanerozoic

Hadean Paleozoic Cambrian explosion First land plant First jaw fish First land vertebrate First seed plant First insects Mass extinction First reptiles

At the other end of the Paleozoic, the largest mass extinction in history wiped out approximately 90% of all marine animal species. The causes of both these events are still not fully understood and the subject is still under much research and controversy. Roughly halfway in between, animals, fungi, and plants alike colonized the land, the insects took to the air.

5 mass extinctions Paleozoic Mesozoic

Permian-Triassic crisis Foraminifera (plankton) 97% Radiolaria (plankton) 99% Antozoa (sea anemones, corals, etc.) 96% Bryozoans79% Brachiopods96% Bivalves59% Gastropods (snails) 98% Ammonites (cephalopods) 97% Crinoids (echinoderms) 98% Blastoids (echinoderms) 100% Trilobites100% Eurypterids ("sea scorpions") 100% Ostracods (small crustaceans) 59% Graptolites100%

The boundary between the two eons (Paleozoic and Mesozoic) is defined because there was a big change in fauna (e.g., Dinosaurs) End of dinosaurs Cambrian explosion First land plant First jaw fish First land vertebrate First seed plant First insects Mass extinction First reptiles First dinosaurs First birds First flowering plants Mammalian reptiles First placental mammal

Mesozoic Era 248 to 65 millions years ago. The Mesozoic is divided into three time periods: the Triassic, the Jurassic, and the Cretaceous

Mesozoic means "middle life", and is the time during which the world fauna changed drastically from that which had been seen in the Paleozoic. Dinosaurs, which are perhaps the most popular organisms of the Mesozoic, evolved in the Triassic, but were not very diverse until the Jurassic.

Except for birds, dinosaurs became extinct at the end of the Cretaceous. Some of the last dinosaurs to have lived are found in the late Cretaceous deposits of Montana in the United States.

The boundary between the two eons (Mesozoic and Cenozoic) is defined because there was a big change in fauna (e.g., non avian Dinosaurs extinct, Mammals explosion)

Cenozoic

Cenozoic Era: 65 millions years ago to the present The Cenozoic is sometimes called the Age of Mammals, because the largest land animals are mammals since that time.

The term “the Age of Mammals, is a misnomer for several reasons: First, the history of mammals began long before the Cenozoic began. Second, the diversity of life during the Cenozoic is far wider than mammals.

The Cenozoic could have been called: the "Age of Flowering Plants" or the "Age of Insects" or the "Age of Teleost Fish" or the "Age of Birds" just as accurately.

If Earth was created 24 hours ago, Life appeared at 02:45. Eukaryotes at 16:00. Humans at 23:59:59