Early Paleozoic (Ordovician)

Question 1

What followed after the Cambrian in the Paleozoic era?

When?

Answer 1

ORDOVICIAN PERIOD

485-444 Million Years Ago

Question 2

What is the Ordovician period considered regarding sea level?

What happened to Laurentia?

Answer 2

HIGHEST SEA LEVEL IN THE PAST 542 MILLION YEARS

At such high sea levels, Laurentia was mostly submerged

Question 3

What was not submerged in Laurentia during the Ordovician?

Answer 3

THE TACONIC OROGENY of the ORDOVICIAN

Represents a major mountain-building event

LATER BECAME APPALACIAN MTS. ^^^^^

Question 4

How did the TACONIC OROGENY (soon to be Appalachian mts.) form?

Answer 4

In the Ordovician, chains of volcanic islands were ACCRETED to the EAST COAST of NA

Question 5

What does the Taconic Orogeny in New York consist of regarding its features? (hint. usual orogenic features)

Answer 5

REVERSE FAULTS, INTRUSIVE IGNEOUS ROCKS, and METAMORPHIC ROCKS make up the orogen

Question 6

What did the Taconic Orogeny introduce to Laurentia that it never had before?

Answer 6

Exotic fossils are those not native to Laurentia that were accreted ALONG with the volcanic island chain

Question 7

Where else have exotic fossils been found besides Laurentia?

Answer 7

Terrane that also collided with NEWFOUNDLAND and BRITAIN

Due to the terrane being disected over time

Question 8

What did the Ordovician also introduce regarding fauna?

Answer 8

PALEOZOIC FAUNA, QUICKLY REPLACES the Cambrian Fauna

Question 9

What do we call this new emergence of life in the Ordovician?

What were some organisms introduced?

Answer 9

ORDOVICIAN RADIATION

This new life would define the Paleozoic

Bryozoans

Corals

Snails

Trilobites

Cephalopods

Bivalves

Brachiopods

Question 10

What had caused the Ordovician Radiation? Why?

Answer 10

Likely due to high sea level rises at the time

Provided plenty of space and environments for organisms to colonize and diversify

Question 11

What are the major organisms that take over the Paleozoic during the Ordovician?

Answer 11

BRACHIPODS, BRYOZOANS, and CRINOIDS

ONLY time they are dominant

Question 12

What do most rocks from the Paleozoic have in great abundance?

Answer 12

Fossils of Brachiopods, Bryozoans, Crinoids

Question 13

What is the trend of inarticulate and articulate brachiopods from the Cambrian to the Ordovician on ward?

Answer 13

Inarticulate brachiopods that dominated the Cambrian are now replaced by the articulate brachiopods during the Ordovician

Question 14

What group of fossils did not show up in the Cambrian but DID show up in the Ordovician?

Answer 14

BRYOZOANS EMERGED IN THE ORDOVICIAN BUT MOST GROUPS WENT EXTINCT BY THE END OF THE PALEOZOIC

Question 15

What group shows a similar trend to the Bryozoans regarding its survival throughout the periods?

Answer 15

CRINOIDS EMERGED IN THE ORDOVICIAN BUT DECLINED BY THE END OF THE PALEOZOIC

Question 16

What was the precursor to the Crinoid?

Answer 16

EOCRINOID THAT DOMINATED IN THE CAMBRIAN

Question 17

What happens to the two fauna (Paleozoic and Cambrian) when they are competing for survival?

Answer 17

The Cambrian fauna slowly moved offshore into deeper waters as the Paleozoic fauna emerges

New evolutionary faunas show up NEARSHORE and slowly push older evolutionary faunas OFFSHORE

Question 18

What happened to the Ordovician phase of evolution?

Answer 18

The Ordovician phase of evolutionary innovation comes to an end with a MASS EXTINCTION EVENT

Question 19

What is a mass extinction event?

How many have there been?

Answer 19

A SEVERE DROP IN DIVERSITY

5 throughout time

Question 20

What happens to Gondwanaland at the end of the Ordovician? What did this do to the environment?

Answer 20

Gondwanaland moves down to the South Pole

This landmass allowed for the ESTABLISHMENT of massive glaciers and A SHORT-LIVED ICE AGE

End of Ordovician = short-lived ice age through Gondwanaland moving down to the South Pole

Question 21

What happened to Ordovician life when this short-lived ice age occurred at the end of the Ordovician?

Answer 21

Most animals would go extinct, Ordovician life was adapted to a warm climate and could not tolerate Earth’s rapid cooling

ALL 3 faunas were hit by the mass extinction event