Warm Up 1/15/08Warm Up 1/15/081. The most common Precambrian fossils are layered mounds of

calcium carbonate called ____.a. prokaryotes c. stromatolitesb. trilobites d. chert

2. Most of the molecular oxygen in the early atmosphere of Earth resulted froma. decaying primitive plants and animals.b. volcanic eruptions.c. lightning striking Earth.d. photosynthesis in primitive plants.

3. How far back does the fossil record extend?a. 3 million years c. 560 million yearsb. 1 billion years d. 3.5 billion years

Answers: 1) c. 2) d. 3) d.

Paleozoic Era: Life Paleozoic Era: Life ExplodesExplodesChapter 13, Section 2Chapter 13, Section 2

Paleozoic EraPaleozoic Era Following the long Precambrian, the most recent 540 Following the long Precambrian, the most recent 540

million years of Earth’s history are divided into three million years of Earth’s history are divided into three eras: Paleozoic, Mesozoic, and Cenozoiceras: Paleozoic, Mesozoic, and Cenozoic

By the beginning of the Paleozoic era, the fossil By the beginning of the Paleozoic era, the fossil record has abundant ocean-dwelling organisms that record has abundant ocean-dwelling organisms that required oxygen to liverequired oxygen to live

This shows that Earth’s atmospheric composition This shows that Earth’s atmospheric composition changed with its evolving life formschanged with its evolving life forms

Before the Paleozoic, life forms possessed no hard Before the Paleozoic, life forms possessed no hard parts (shells, scales, bones, etc)parts (shells, scales, bones, etc)

The Paleozoic era contains many more diverse The Paleozoic era contains many more diverse fossils due to the emergence of life forms with hard fossils due to the emergence of life forms with hard partsparts

Early Paleozoic HistoryEarly Paleozoic History The early Paleozoic consists of a 123-million-year The early Paleozoic consists of a 123-million-year

span that includes the Cambrian, Ordovician, and span that includes the Cambrian, Ordovician, and Silurian periodsSilurian periods

During the Cambrian, Ordovician, and Silurian During the Cambrian, Ordovician, and Silurian periods, the vast southern continent ofperiods, the vast southern continent of Gondwana Gondwana encompassed five of today’s continents (South encompassed five of today’s continents (South America, Africa, Australia, Antarctica, and parts of America, Africa, Australia, Antarctica, and parts of Asia)Asia)

The exact positions of the northern continents are not The exact positions of the northern continents are not known, but are thought to have been around the known, but are thought to have been around the equatorequator

At the beginning of the Paleozoic, North America was At the beginning of the Paleozoic, North America was a land with no living things, plant or animala land with no living things, plant or animal

A mountain building event occurred and over 200 A mountain building event occurred and over 200 million years later the Appalachian Mountains were million years later the Appalachian Mountains were formedformed

Earth in Early Paleozoic Earth in Early Paleozoic TimeTime

Concept CheckConcept Check

Why are more fossils found from the Why are more fossils found from the Paleozoic era than Precambrian time?Paleozoic era than Precambrian time?

There were more organisms with hard There were more organisms with hard parts, which greatly enhanced a life-parts, which greatly enhanced a life-form’s chance of being preserved in the form’s chance of being preserved in the fossil record.fossil record.

Early Paleozoic LifeEarly Paleozoic Life Life in the early Paleozoic time was restricted to the Life in the early Paleozoic time was restricted to the

seasseas Vertebrates had not yet evolved, so life consisted of Vertebrates had not yet evolved, so life consisted of

several invertebrate groupsseveral invertebrate groups The Cambrian period was the golden age of trilobites; The Cambrian period was the golden age of trilobites;

more than 600 types of these mud-burrowing more than 600 types of these mud-burrowing scavenger flourished around the worldscavenger flourished around the world

By Ordovician times, brachiopods outnumbered By Ordovician times, brachiopods outnumbered trilobites, and are among the most widespread of trilobites, and are among the most widespread of Paleozoic fossilsPaleozoic fossils

The Ordovician also marked the appearance of the The Ordovician also marked the appearance of the first cephalopods—mobile and highly developed first cephalopods—mobile and highly developed mollusks that became the major predators of the time mollusks that became the major predators of the time (squid and octopus are modern day descendents)(squid and octopus are modern day descendents)

The beginning of the Cambrian marks a turning point The beginning of the Cambrian marks a turning point in animal evolution, with the creation of exoskeletons in animal evolution, with the creation of exoskeletons (hard parts)(hard parts)

Early Paleozoic LifeEarly Paleozoic Life

In the image above, trilobites (1) live among many species that are not normally preserved. A typical Cambrian outcrop might produce only trilobites, brachiopods (2), mollusks (3), and crinoids (4). That is a tiny fraction of the full Cambrian biota, better represented by the roster of the Burgess Shale Cambrian Konservat-Lagerstatten. That community includes sponges Vauxia (5), Hazelia (6), and Eifellia (7); brachipods Nisusia (2); priapulid worms Ottoia (8); trilobites Olenoides (1); other arthropods such as Sidneyia (9), Leanchoilia (10), Marella (11), Canadaspis (12), Helmetia (13), Burgessia (14), Tegopelte (15), Naraoia (16), Waptia (17), Sanctacaris (18), and Odaraia (19); lobopods Hallucigenia (20) and Aysheaia (21); mollusks Scenella (3); echinoderms Echmatocrinus (4); and chordates Pikaia (22); among other oddities, including Haplophrentis (23), Opabinia (24), Dinomischus (25), Wiwaxia (26), Amiskwia (27), and Anomalocaris (28).

Concept CheckConcept Check

How did the formation of hard parts How did the formation of hard parts benefit animals?benefit animals?

Hard parts allowed animals to venture Hard parts allowed animals to venture into different environments.into different environments.

Late Paleozoic HistoryLate Paleozoic History The late Paleozoic consists of four periods—the The late Paleozoic consists of four periods—the

Devonian, Mississippian, Pennsylvanian, and PermianDevonian, Mississippian, Pennsylvanian, and Permian—that span about 160 million years—that span about 160 million years

As ancestral North America collided with Africa, it As ancestral North America collided with Africa, it deformed rocks to produce the Appalachian Mountain deformed rocks to produce the Appalachian Mountain of eastern North Americaof eastern North America

During the union of North America and Africa, the During the union of North America and Africa, the other northern continents began to joinother northern continents began to join

By the Permian period the northern continent of By the Permian period the northern continent of LaurasiaLaurasia was created, made up of present-day North was created, made up of present-day North America, Europe, and western AsiaAmerica, Europe, and western Asia

As Laurasia was forming, Gondwana moved As Laurasia was forming, Gondwana moved northward, and by the Pennsylvanian period it was northward, and by the Pennsylvanian period it was colliding with Laurasiacolliding with Laurasia

By the end of the Paleozoic, all the continents had By the end of the Paleozoic, all the continents had fused together into the supercontinent of Pangaeafused together into the supercontinent of Pangaea

View of Earth—Devonian View of Earth—Devonian Period (410 MA)Period (410 MA)

View of Earth—View of Earth—Mississippian Period (330 Mississippian Period (330 MA)MA)

View of Earth—Permian View of Earth—Permian Period (260 MA)Period (260 MA)

Late Paleozoic LifeLate Paleozoic Life Some 400 million years ago, plants that had adapted Some 400 million years ago, plants that had adapted

to survive at the water’s edge began to move inland, to survive at the water’s edge began to move inland, becoming land plantsbecoming land plants

The earliest land plants were leafless vertical spikes The earliest land plants were leafless vertical spikes about the size of your index fingerabout the size of your index finger

By the end of the Devonian, 40 million years later, the By the end of the Devonian, 40 million years later, the fossil record indicates the existence of forests with fossil record indicates the existence of forests with trees tens of meters hightrees tens of meters high

In the oceans, armor-plated fishes that had evolved In the oceans, armor-plated fishes that had evolved during the Ordovician continued to adapt (with the during the Ordovician continued to adapt (with the armor thinning to light-weight scales)armor thinning to light-weight scales)

By the late Devonian, several fish became adapted to By the late Devonian, several fish became adapted to land environments, becoming amphibians with the land environments, becoming amphibians with the ability to breath airability to breath air

The amphibians rapidly diversified because they had The amphibians rapidly diversified because they had minimal competition from other land dwellersminimal competition from other land dwellers

Late Paleozoic LifeLate Paleozoic Life

Concept CheckConcept Check

What allowed amphibians to flourish on What allowed amphibians to flourish on land?land?

Amphibians were able to colonize areas Amphibians were able to colonize areas that other animals were not. The lack of that other animals were not. The lack of competition for resources allowed competition for resources allowed amphibians to be successful.amphibians to be successful.

The Great Paleozoic ExtinctionThe Great Paleozoic Extinction The redistribution of land to form Pangaea, at the end of the The redistribution of land to form Pangaea, at the end of the

Paleozoic, caused drastic changes in Earth’s climatePaleozoic, caused drastic changes in Earth’s climate Broad areas of the northern continents became elevated above Broad areas of the northern continents became elevated above

sea level, and the climate became driersea level, and the climate became drier These climate changes are believed to have triggered These climate changes are believed to have triggered

extinctions of many species on land and seaextinctions of many species on land and sea By the close of the Permian, 75% of amphibian families had By the close of the Permian, 75% of amphibian families had

disappeared, and plants had declined in number and varietydisappeared, and plants had declined in number and variety Although many of the amphibian families would become Although many of the amphibian families would become

extinct, their descendents, the reptiles, would become the extinct, their descendents, the reptiles, would become the dominant life form on Earthdominant life form on Earth

Much of the marine life did not adapt and survive, with Much of the marine life did not adapt and survive, with estimates ranging from 80-95% extinction of marine lifeestimates ranging from 80-95% extinction of marine life

The late Paleozoic extinction was the greatest of at least 5 to The late Paleozoic extinction was the greatest of at least 5 to occur over the last 500 million yearsoccur over the last 500 million years

Mass extinctions actually allowed life to flourish on Earth, as the Mass extinctions actually allowed life to flourish on Earth, as the few survivors eventually filled more niches than the ones left by few survivors eventually filled more niches than the ones left by the victimsthe victims

AssignmentAssignment

Read Chapter 13, Section 2 (pg. 369-376)Read Chapter 13, Section 2 (pg. 369-376) Do Section 13.2 Assessment #1-6 (pg. 376)Do Section 13.2 Assessment #1-6 (pg. 376)