Early Paleozoic (Ordovician) Flashcards
What followed after the Cambrian in the Paleozoic era?
When?
ORDOVICIAN PERIOD
485-444 Million Years Ago
What is the Ordovician period considered regarding sea level?
What happened to Laurentia?
HIGHEST SEA LEVEL IN THE PAST 542 MILLION YEARS
At such high sea levels, Laurentia was mostly submerged
What was not submerged in Laurentia during the Ordovician?
THE TACONIC OROGENY of the ORDOVICIAN
Represents a major mountain-building event
LATER BECAME APPALACIAN MTS. ^^^^^
How did the TACONIC OROGENY (soon to be Appalachian mts.) form?
In the Ordovician, chains of volcanic islands were ACCRETED to the EAST COAST of NA
What does the Taconic Orogeny in New York consist of regarding its features? (hint. usual orogenic features)
REVERSE FAULTS, INTRUSIVE IGNEOUS ROCKS, and METAMORPHIC ROCKS make up the orogen
What did the Taconic Orogeny introduce to Laurentia that it never had before?
Exotic fossils are those not native to Laurentia that were accreted ALONG with the volcanic island chain
Where else have exotic fossils been found besides Laurentia?
Terrane that also collided with NEWFOUNDLAND and BRITAIN
Due to the terrane being disected over time
What did the Ordovician also introduce regarding fauna?
PALEOZOIC FAUNA, QUICKLY REPLACES the Cambrian Fauna
What do we call this new emergence of life in the Ordovician?
What were some organisms introduced?
ORDOVICIAN RADIATION
This new life would define the Paleozoic
Bryozoans
Corals
Snails
Trilobites
Cephalopods
Bivalves
Brachiopods
What had caused the Ordovician Radiation? Why?
Likely due to high sea level rises at the time
Provided plenty of space and environments for organisms to colonize and diversify
What are the major organisms that take over the Paleozoic during the Ordovician?
BRACHIPODS, BRYOZOANS, and CRINOIDS
ONLY time they are dominant
What do most rocks from the Paleozoic have in great abundance?
Fossils of Brachiopods, Bryozoans, Crinoids
What is the trend of inarticulate and articulate brachiopods from the Cambrian to the Ordovician on ward?
Inarticulate brachiopods that dominated the Cambrian are now replaced by the articulate brachiopods during the Ordovician
What group of fossils did not show up in the Cambrian but DID show up in the Ordovician?
BRYOZOANS EMERGED IN THE ORDOVICIAN BUT MOST GROUPS WENT EXTINCT BY THE END OF THE PALEOZOIC
What group shows a similar trend to the Bryozoans regarding its survival throughout the periods?
CRINOIDS EMERGED IN THE ORDOVICIAN BUT DECLINED BY THE END OF THE PALEOZOIC
What was the precursor to the Crinoid?
EOCRINOID THAT DOMINATED IN THE CAMBRIAN
What happens to the two fauna (Paleozoic and Cambrian) when they are competing for survival?
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
What happened to the Ordovician phase of evolution?
The Ordovician phase of evolutionary innovation comes to an end with a MASS EXTINCTION EVENT
What is a mass extinction event?
How many have there been?
A SEVERE DROP IN DIVERSITY
5 throughout time
What happens to Gondwanaland at the end of the Ordovician? What did this do to the environment?
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
What happened to Ordovician life when this short-lived ice age occurred at the end of the Ordovician?
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
