*foto’s slide 9,10,11,12,13,14,15,16,17,18,19,20,21 van Silurian Silurian Terrestrial Ecosystems

• The most important evolutionary development of this period, was that of the first true terrestrial ecosystems

• The first fossil records of vascular plants, that is, land plants with tissue that carries food. They were simple plants that had not developed separate stems and leaves

• 1990 discovery of the earliest fossil terrestrial animals, from the Late Silurian of England. Mainly arachnids and myriapods, from Europe and North America

Devonian The period is named for Devonshire, Southwest England where Devonian outcrops are common. While the rock beds that define the start and end of the period are well identified.

Paleogeography During the Devonian, there were three major continental masses:

• North America and Europe sat together near the equator, much of their current land underneath seas.

• To the north lay a portion of modern Siberia. • A composite continent of South America, Africa, Antarctica, India, and Australia

dominated the southern hemisphere. • Sea levels were high worldwide. • Extensive sedimentary record of Devonian period. • Reefs, carbonates, evaporites suggest warm climate

Tectonics

It is a time of great tectonic activity

• Acadian Orogeny.

• Iapetus Ocean (Proto-Atlantic) closed.

• Laurentia and Baltica collided, forming a mountain belt.

Devonian life

Two major animal groups colonized the land.

• The first tetrapods, or land-living vertebrates, appeared

• The first terrestrial arthropods, including wingless insects and the earliest arachnids

Tectonic phases

Devonian vegetation The vegetation of the Early Devonian consisted primarily of small plants, the tallest being only a meter tall. By the end of the Devonian, ferns, horsetails and seed plants had also appeared, producing the first trees and the first forests in swampy areas Late Devonian extinction

• 70% of all species vanished. • Marine species were most affected - Brachiopods, ammonites and many other

invertebrate groups suffered heavily, as did Agnathan and Placoderm fish. • On land, where plants were diversifying and amphibians were beginning their evolution,

there seem to be have been far fewer losses. • The causes are far from clear. The disproportionate losses amongst warm water species

suggest that a global cooling, was an important factor probably associated with (or may even have caused) a drop in the oxygen levels of these shallower waters

Carboniferous Carboniferous subdivision Zie slide 3 van Carboniferous Name Coal Measures was proposed in 1807 and 1811. Term Carboniferous - coal bearing - was proposed by English geologists 1822 to designate coal-bearing strata in north-central England. It was the first geological period to be established. Mississippian and Pennsylvanian In Continental Europe and Britain the system was divided into a Lower and an Upper Carboniferous. In America the name Mississippian was proposed in 1869 for Lower Carboniferous strata along the Mississippi River drainage region In 1891 introduction of the Pennsylvanian for the Upper Carboniferous. Formerly the terms Mississippian and Pennsylvanian Periods only used by American geologists. At present: accepted as a single international standard for the period. Climate The early part of the period is mostly warm, but there is a pronounced cooling and glaciation during the second half, triggered by Gondwanaland's southward migration. Although the equatorial regions remain warm and wet and tropical, the poles are gripped in a massive ice age, one that lasts for many millions of years. Vast sheets of ice cover Gondwanaland

Mississippian Is characterized by deposition of mostly thick marine limestones in shallow, tropical seas.

Pennsylvanian

It contains mostly sediments and coal seams created by meandering river deltas periodically

interrupted by marine inundations. Many places around the world contain important coal beds

deposited during this time period

Paleogeography

• Gondwana rotates over south pole (glaciation) and then drifts north towards equator

and Laurentia. Closure of Laurentia and Gondwana towards end of Carboniferous results

in Ouachita/southern Appalachian/Hercynian mobile belts.

• China and Kazakhstania collide with Siberia.

• The supercontinent Pangaea begins to take shape.

• Large coal deposits form in Laurasia/Siberia as a result of location on equator thru

Carboniferous

*foto’s 12-20 in Carboniferous

Life on the Land

1. Plant Life

• More plant fossils in Carboniferous strata than in any other geologic interval.

• Coal deposits formed from plant remains in lowland swamps.

• Coal represents an enormous biomass of plants.

2. Freshwater and Terrestrial Animals

• Aquatic habitats

Ray-finned fishes diversity.

Freshwater sharks.

Molluscs became common - such as clam shells associated with coal deposits.

• Terrestrial habitats

1. Insects had important ecological roles

Food for other animals

Consume and decompose plants and animals

Insects first appeared in Devonian - wingless.

Wings appeared by the Late Carboniferous.

2. Vertebrates

– Amphibians

• First appeared Late Devonian

• Aquatic or semi-aquatic

• Eggs and young in water

• Broad spectrum of shapes, sizes, and modes of life.

• Were up to 20 feet in length (but most living amphibians are small).

– Reptiles

• First appeared in the Pennsylvanian

• First found in Nova Scotia inside hollow trees filled with sediment

Role of the egg

The key feature in the origin of reptiles is the development of the amniotic egg.

- Durable outer shell protects embryo from drying

- Egg can be laid on land

- Yolky part of egg provides nutrition; sac contains embryo and another sac collects waste

products.

- Eliminated need to lay eggs in water, allowing vertebrates to live and reproduce on dry

land for the first time.

- Amniotic egg probably evolved in Carboniferous.

- First fossil eggs are early Permian

Reproduction on land

Similar adaptations occurred in plants and then in animals allowing reproduction on dry land:

Plant reproductive structure is seed (Devonian).

• Animal reproductive structure is amniotic egg (Carboniferous).

Permian

The Permian period was named in 1841 by the geologist Murchison after a tour of Imperial

Russia to include the "vast series of beds of marls, schists, limestones, sandstones, and

conglomerates" that overlay the Carboniferous formations in the eastern part of the country.

Named after the ancient kingdom of Permia and the present city of Perm near the Ural

mountains

Plate tectonic setting

• The continents came together to form the supercontinent Pangea.

• Several mountain chains formed

Orogeny as continents collided

Appalachian or Alleghanian orogeny

Permian subdivision

In West Europe subdivision in: • Upper Permian: Zechstein • Lower Permian: Rotliegend

Climate

• Major climatic changes • Glaciers spread over Gondwanaland then melted and retreated • Drying of climates at low latitudes led to contraction of coal swamps and extinctions

among spore-bearing plants and amphibians. • Evaporites accumulated in many areas • Locations of mountains can affect climate and control precipitation (Rain shadow) • Late Permian was a time of widespread regression of the seas. • Gymnosperms (seed plants) replaced many spore bearing plants. Conifers

• Probably as a response to climatic warming and drying after the glaciation. • Widespread accumulation of evaporites. More of Permian salt deposits than of any

other age • Waters were hypersaline

*foto’s 10-12 slide Permian en 15-17 End Permian Mass extinction

• trilobites all disappeared • rugose and tabulate corals all disappeared • blastoids all disappeared

Fusulinid forams all disappeared

Triassic

In 1834 Friedrich August von Alberti recognized three distinctive formations in southern Germany. These are the :

• Keuper: Upper Triassic • Muschelkalk: Middle Triassic • Buntsandstein: Lower Triassic

Early Triassic Paleogeography

• Almost all the Earth's land mass was concentrated into a single supercontinent centered more or less on the equator, called Pangea ("all the land").

• The Paleo Tethys was a vast gulf that opened farther westwards in the mid-Triassic. • The remainder was the world-ocean known as Panthalassa ("all the sea").

Climate

• Generally hot and dry • Forming typical redbed sandstones. • Seasonal, continental climate, with strong monsoons

• Polar regions were moist and temperate Triassic terrestrial life Triassic important because all living dominant tetrapods evolved by its end. These include:

• Salamanders • Frogs • Turtles • Dinosaurs (now surviving as birds) • Mamals • Crocodiles • Lizards (incl. sphenodonts & snakes) • Also Pterosaurs • Origin of Angiosperms (possibly)

Early Triassic marine life

• In the oceans, ammonites recover, and the first modern corals appear. • At first a remarkably uniform fish fauna - perhaps even at the species level. This was

probably a result of the end-Permian mass extinction. • Reptiles were at first very rare in the oceans but they became more and more common

through time. Late Triassic paleogeography

• Continents (Pangea) remained united, but North American and Eurasian Plate (Laurasia) began to move from the other plates (collectively called Gondwanaland).

• Large series of rift valleys formed along the stretching crust that in the Jurassic would become the Central Atlantic Ocean.

• On opposite sides of the plates there was convergence. • These plate movements created a much larger array of basins that preserved Late

Triassic (and Early Jurassic), largely continental strata. • Therefore much more is known about the Late Triassic than either the Early or Middle

Triassic. Dinosaurs

• The term 'dinosaur' originates from the Greek words deino and sauros, meaning 'terrible' and 'lizard'.

• Dinosaurs show a range of adaptations to a wide range of environments and conditions, and as a result they became the most successful land animals of all time.

• Dinosaurs were reptiles (horny or scaly skinned tetrapods that lay eggs) which lived on land during the Mesozoic Era.

• Dinosaurs arose in the Middle or Late Triassic, some 235-230 million years ago. The large marine reptiles and the flying reptiles of the Mesozoic were not dinosaurs.

Jurassic Outside the park… Named for the Jura Mountains (1795, Alexander von Humbolt) on the border between France and Switzerland. The Jurassic has become a household word with the success of the movie Jurassic Park. The Jurassic is important, both because of its wealth of fossils and because of its economic importance -- the oilfields of the North Sea, for instance, are Jurassic in age. Classical Jurassic subdivision

• Upper Jurassic: Malm • Middle Jurassic: Dogger • Lower Jurassic: Liassic

Jurassic time scale

Jurassic Stratigraphy

Jurassic paleogeography

• By the Early Jurassic, south-central Asia had assembled.

• A wide Tethys ocean separated the northern continents from Gondwana.

• Though Pangea was intact, the first rumblings of continental break up could be heard.

• In the Early Jurassic, Pangea was breaking up between modern North America, Africa,

and South America.

• By the Middle Jurassic, these rifts were opening up the Central Atlantic Ocean and the

Gulf of Mexico formed. Rifting between North America and Eurasia began forming the North

Atlantic Ocean while closing the Tethys Ocean.

At the same time, volcanic activity began along adjacent margins of East Africa, Antarctica, and Madagascar, where the South Atlantic Ocean would later form. Jurassic climate

• Global climate during the Jurassic was relatively warm and moist over much of northern North America, Eurasia, and Indo-Australian Gondwana.

• Desert and seasonally wet conditions were present throughout much of Africa, South America, and southern North America.

Late Jurassic paleogeography

• The supercontinent of Pangea began to break apart in the Middle Jurassic. • In the Late Jurassic the Central Atlantic Ocean was a narrow ocean separating Africa

from eastern North America. • Eastern Gondwana had begun to separate form Western Gondwana

Cretaceous In 1822 the Belgian geologist D'Omalius d'Halloy gave the name Terrain Cretace, for the chalk and rock outcrops of the Paris Basin, and for similar deposits in Belgium and Holland and traceable also from England eastward into Sweden and Poland. "Cretaceous" "chalk-bearing" (from Creta, the Latin word for chalk) later came to be used. The famous White Cliffs of Dover, are typical of this rock formation. Extensive chalk deposits were laid down in Europe and parts of North America during this period. The chalk itself is actually formed from the shells of countless micro-organisms.

Cretaceous paleogeography The breakup of the supercontinent Pangaea into separate continents was underway. The separation of Laurasia and Gondwana was complete. Climate

• In the first half of the Cretaceous, temperatures were warm, subtropical, seasonality was low, and global sea levels were high (no polar ice!).

• At the end of the Cretaceous, there were severe climate changes, lowered sea levels, and high volcanic activity .

• The land was covered with forests surrounded by shallow seas. Cretaceous paleogeography

• Most land mass was at or around sea level until the mid-Cret.; much tectonic activity (continental plate movement) and volcanic activity.

• Many mountains were formed e.g. Sierra Nevadas, Rocky Mountains (USA) and the European Alps.

• Mid-Cret. sea level rose, covering ± 1/3 of the land area. • Near the end of the Cret.: drop in sea level, causing land exposure on all continents,

more seasonality, and greater extremes between equatorial and polar temperatures. • The continents were taking on their modern-day forms

Life in the Cretaceous

• No great extinction or burst of diversity separated the Cretaceous from the Jurassic. In some ways, things went on as they had.

• Dinosaurs both great and small moved through forests of ferns, cycads, and conifers. • Ammonites, belemnites, other molluscs, and fish were hunted by great "marine

reptiles," and pterosaurs and birds flapped and soared in the air above. Yet the Cretaceous saw the first appearance of many lifeforms that would go on to play key roles in the coming Cenozoic world.

*Foto’s 11-14 slide Cretaceous The development of plants

• The first appearance of the flowering plants, also called the angiosperms or Anthophyta in the Early Cretaceous

• The flowering plants first radiated in the Middle Cretaceous. • By the close of the Cretaceous, a number of forms had evolved that any modern

botanist would recognize. Land life

• In the Cretaceous, many modern groups of insects were beginning to diversify, and we find the oldest known ants and butterflies. Aphids, grasshoppers, and gall wasps appear, as well as termites and ants in the later part of this period.

• Another important insect to evolve was the eusocial bee, which was integral to the ecology and evolution of flowering plants.

• Also the first radiation of the diatoms in the oceans. The end Cretaceous extinction

• The Cretaceous period ended with a bang! • About 65 million years ago, a mass extinction wiped out the dinosaurs (except for the

birds) and many other animals, including pterosaurs , ichthyosaurs , ammonites, mosasaurs, plesiosaurs, and half of all invertebrate marine organisms.

• The primary cause of the Cretaceous-Tertiary extinction is thought to be an asteroid impact

The K-T Boundary

• Evidence for catastrophism at the Cretaceous-Tertiary boundary is found in a layer of sediment which was deposited at the same time that the extinction occurred.

• This layer contains unusually high concentrations of Iridium, found only in the earth's mantle, and in extra-terrestrial meteors and comets.

• It has been found found in both marine and terrestrial sediments, at numerous boundary sites around the world.

Evidence of an extra- terrestrial impact

• Widespread distribution of Iridium layer could have only been caused by meteorite impact.

• Abundance of small droplets of basalt (spherules) evidence that basalt from the crust was melted and flung into the air upon impact.

• Presence of shocked quartz - tiny grains of quartz that show features of the high pressure of impact layer.

• Recent research suggests that the impact site may have been in the Yucatan Peninsula of Mexico.

Another cause

• High concentrations of Iridium can also be the result of a massive volcanic eruption, as evidenced by the Deccan Traps (India and Pakistan).Flows: > 100,000 km2 , 150 m thick.

• Such flows would have produced enormous amounts of ash, altering global climatic conditions and changing ocean chemistry.

• Presence of spherules and shocked quartz may also have been the result of such explosive volcanism.

The K-T mass extinction

• During (K-T) extinction 85% of all species disappeared, making it the second largest mass extinction event in geological history.

• In addition to the dinosaurs, other terrestrial and marine biotic groups were also severely affected or eliminated in the crisis.

• Among those that perished were the pterosaurs, belemnoids, many species of plants (except amongst the ferns and seed-producing plants), ammonoids, marine reptiles, and rudist bivalves.

• Organisms which were severely affected included planktic foraminifera, calcareous nannoplankton, diatoms, dinoflagellates, brachiopods, molluscs, echinoids, and fish.

Most mammals, birds, turtles, crocodiles, lizards, snakes, and amphibians were primarily unaffected by the End-Cretaceous mass extinction. The impact The asteroid or comet that produced the Chicxulub crater was roughly 10 km in diameter. When an object that size hits Earth's surface, it causes a tremendous shock comparable to 100 million megatons of TNT, 6 million times more energetic than the 1980 Mount St. Helens volcanic eruption. The impact ejected rock from several kilometers beneath the surface of the Earth and carved out a bowl-shaped crater nearly 100 km in diameter. In addition, the shock of the impact produced magnitude-10 earthquakes, which were greater than the magnitude of any we have ever measured in modern times.

Crater Site

Drilling results

• One of the wells, Yucatan-6, penetrated the flank of the ~100 km ring and samples of the polymict breccia and melt rock were recovered.

• The polymict breccia consists of igneous-textured microcrystalline clasts with shocked quartz xenoliths, and vesicular and ropy textured phyllosilicate clasts which look like altered fragments of glass, both of which were produced by shock melting.

• The breccia also contains clasts of sedimentary carbonates and evaporites, recrystallized sandstone, granitic gneisses and mica schists in a carbonate-rich matrix.

Tertiary Cenozoic

• The Cenozoic covers the 65.5 million years since the K-T extinction event. It is ongoing. • Cenozoic is divided into Paleogene and Neogene, and they are in turn divided into

epochs. • Paleogene consists of Paleocene, Eocene, and Oligocene. • Neogene consists of Miocene, Pliocene, Pleistocene, and Holocene which is ongoing. • Previously Cenozoic was divided into periods (or sub-eras) named as Tertiary (Paleocene

to Pliocene) and Quaternary (Pleistocene and Holocene). However, they are no longer recognized

Subdivision of the Tertiary

Tertiary First used by Giovanni Arduino in the 1700's. He classified geologic time into primitive (or primary), secondary, and Tertiary periods based on observations of geology in northern Italy. Later a fourth period, the Quaternary, was applied. Lyell subdivided the Tertiary period into four epochs according to the percentage of fossil mollusks resembling Modern species found in those strata. He used Greek names: Eocene, Miocene, Older Pliocene and Newer Pliocene. Although these divisions seemed adequate for the region to which the designations were originally applied it proved to be inapplicable in other parts of the world. Therefore, later the use of mollusks was abandoned from the definition and the epochs were renamed and redefined Paleogeography

• The last phase of the breakup of Pangea was accompanied by several continental collisions. North America and Greenland split from each other and from Europe, while Arabia was rifting away from Africa.

• These movements also formed the Gulf of Mexico, the African Rift Valley, the Red Sea and the Sea of Japan.

• Elsewhere, colliding continents resulted in several mountain chains (e.g Pyrenees, Alps, the Himalayas and Tibetan Plateau).

• These continental collisions raised high mountains and resulted in lower sea levels around the world, causing shifting climates.

Cenozoic life

• The K-T extinction opened numerous ecological niches, filled mostly by mammals undergoing a dramatic evolutionary radiation (mastodons, ground sloths, armadillos, camels, horses, saber tooth cats, giant wolves, giant beavers, and giant bears)

• In the seas gastropods and bivalves were very similar to modern forms. Squids replaced the ammonites. Sea urchins and single-celled foraminifera were still abundant, but new forms appeared. Sharks and bony fishes were common.

Tertiary climate Climates during the Tertiary slowly cooled, starting off in the Paleocene with tropical-to-moderate worldwide temperatures and ending up with extensive glaciations at the end of the period. Pleistocene

• During the last 2.5-3 million y. glaciers accumulated over 27 % of the land • Cooling of the oceans • Freshwater lakes in inland basins • Freezing of extensive tracts of soil and rock

Life in the Pleistocene

• Great disturbance in the organic world • Plants and animals were forced to migrate • Reduction of productivity of the land • Notable exterminations; especially among larger mammals • Greatest extincions after glaciations

Duration ice age

• Duration and subdivision are not yet fully known • Estmates of total length of the Pleistocene range from a few thousand to 3 million years • Clear proof that there are at least 4 avances of continental glaciers • Minor oscillations may have occurred

Cause of glaciations

• Two groups: • 1) Astronomical

2) Terrestrial (recent: shifts in ocean currents)

Are we still in the Ice Age? Probably yes, we are in an interval between two glacials

Pleistoceen • During the last 2.5-3 million y. glaciers accumulated over 27 % of the land • Cooling of the oceans • Freshwater lakes in inland basins • Freezing of extensive tracts of soil and rock

Life in the Pleistocene

• Great disturbance in the organic world • Plants and animals were forced to migrate • Reduction of productivity of the land • Notable exterminations; especially among larger mammals • Greatest extincions after glaciations

Duration ice age

• Duration and subdivision are not yet fully known • Estmates of total length of the Pleistocene range from a few thousand to 3 million years • Clear proof that there are at least 4 avances of continental glaciers • Minor oscillations may have occurred

Glacials and interglacials

Human Evolution

Evolution of apes and man