LECTURE 4: Paleozoic Era (543mya-245 mya)



LECTURE 3: Paleozoic Era: Cambrian/Ordovician Periods

(543mya-245 mya)

• What Life existed in the Early Cambrian Period (543 mya)?

o Late Precambrian Period

▪ Ediacaran Fauna

▪ Limited Diversity

o Early Cambrian Period (543-530 mya)

▪ The “small, shelly fauna”

▪ First Appearance of skeletalized parts: tiny plates, cones, and tubes, made of various minerals

▪ Plant life is essentially limited to ___________________________

• TIMELINE OF CAMBRIAN EVENTS

o 530 mya – Cambrian Explosion

▪ 8 animal phyla

• Porifera (sponges)

• Cnidaria (jellyfish, corals)

• Platyhelminthes (flatworms)

• Arthropods (Trilobites)

• Mollusks (bivalves/gastropods/nautiloids)

• Echinoderms (Sea Stars)

• Annelids (worms, leeches)

• Chordates (spinal tube/Graptolites?)

o 500 mya – First Vertebrate

▪ First Jawless fish: Myllokunmingia

o By the end of the Cambrian:

▪ Trilobites DOMINATE

• What was the Cambrian Explosion?

o most animals appear in a relatively _____________time in history (~530-520 mya)

o great diversity of _____________________________________

o All 8 animal phyla first appear in the fossil record: _________________ flourished

o all of the eight major animals body plans in existence today, along with 27 minor ones, had emerged and no new body plans have developed since

• What Trace Fossil marks the Beginning of the Cambrian Period?

o Trichophycus pedum

▪ Burrowing animal

▪ No ____________________________________

• What was the Burgess Shale?

o Rocky Mountains of British Columbia

o Discovered in 1899

o It is ________________________________ million years old

o Celebrated for its preservation of ____________________________________

o Showed that ________________________________ Dominated!!

• Why did the Cambrian Explosion Occur?

o Increased _______________________________in the atmosphere

▪ At low ___________________levels, only simple metabolic tasks can occur

▪ At high ________________levels, more energy can be exerted to other tasks

• Skeletonization

• Low 02 levels, only small, _________________________ forms

• Allows larger body size- ________________________ relationship

o Predator-Prey Arms Races

▪ First Predators arose during Cambrian (_________________________)

▪ This led to selection of diverse _______________________adaptations

▪ _______________________________________________ prey

▪ Shells in guts of large predators

• What was the First Vertebrate?

o First Jawless fish (___________________________): Myllokunmingia 500 mya

▪ Ancestor to Living Jawless Fish (_________________________________)

• What Significant Event Happened at the end of Ordovician Period(500 mya- 439mya)?

o _______________________________________ #1 (439 mya)

▪ At least ______________________________ of all species were wiped out.

▪ Many species of trilobites, brachiopods, echinoderms, graptolites, and corals became _____________________________

• Why did this Mass Extinction Occur?

o Global ______________________________________________

▪ Gondwana moved over the South Pole, causing glaciers to form and global temperatures to ______________________________________

▪ Many species could ___________________________ cooler conditions

▪ Suffered from ________________________________ as water turned to ice, lowering sea levels worldwide.

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