LECTURE 4: PALEOZOIC ERA Cambrian/Ordovician Periods

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LECTURE 4 PALEOZOIC ERACambrian/Ordovician
Periods
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STUDY THIS PICTURE!
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What Life existed in the Early Cambrian Period
(543 mya)?

• Late Precambrian Period
• Ediacaran Fauna
• Limited Diversity
• 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 Algae

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Timeline of Cambrian Events (543 mya 500 mya)

• 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?)
• 500 mya First Vertebrate
• First Jawless fish Myllokunmingia
• By the end of the Cambrian
• Trilobites DOMINATE

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Make a cladogram Lab?
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What was the Cambrian Explosion?

• most animals appear in a relatively BRIEF time in
  history (530-520 mya)
• great diversity of marine invertebrates
• All 8 animal phyla first appear in the fossil
  record hard parts flourished
• 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

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What Animals appear in the Cambrian Explosion?

• Porifera (sponges)
• Cnidaria (jellyfish, corals)
• Platyhelminthes (flatworms)
• Arthropods (Jointed appendages, segmented bodies
  )
• Mollusks (bivalves/gastropods)
• Echinoderms (Sea Stars)
• Annelids (worms, leeches)
• Chordates (spinal cord)

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What Trace Fossil marks the Beginning of the
Cambrian Period?

• Trichophycus pedum
• Burrowing animal
• No hard parts

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What is the Burgess Shale?

• Rocky Mountains of British Columbia
• Discovered in 1899
• It is 505 million years old
• Celebrated for its preservation of soft parts
• Showed that Trilobites Dominated!!

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Burgess Shale Fauna
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Canapaptsis
Hallucigenia
Wapatia
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Pikaia (earliest chordate)
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Anomalocaris
Wiwaxia
Opabinia
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Why did the Cambrian Explosion Occur?

• Increased Oxygen in the atmosphere
• At low O2 levels, only simple metabolic tasks can
  occur
• At high O2 levels, more energy can be exerted to
  other tasks
• Skeletonization
• Low 02 levels, only small, soft bodied forms
• Allows larger body size- predator-prey
  relationship
• Predator-Prey Arms Races
• First Predators arose during Cambrian (Flatworms)
• This led to selection of diverse hunting
  adaptations
• Heavily Armored prey
• Shells in guts of large predators

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What was the First Vertebrate? First Jawless
fish Myllokunmingia 500 myaAncestor to Living
Jawless Fish (Lampreys)
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What Significant Event Happened at the end of
Ordovician Period (500 mya- 439mya)?

• MASS EXTINCTION 1 (439 mya)
• At least 70 of all species were wiped out.
• Many species of trilobites, brachiopods,
  echinoderms, graptolites, and corals became
  extinct

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Why did the Mass Extinction Happen?

• Global Cooling
• Gondwana moved over the South Pole, causing
  glaciers to form and global temperatures to cool.
  
• Many species could not survive cooler conditions
• Suffered from habitat loss as water turned to
  ice, lowering sea levels worldwide.

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What did the Continents Look Like?
Continental Drift Animation Continent Animation
600 mya to 50 mya
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PALEOZOIC (543-245 mya)

• 543 billion- Ozone Layer forms
• 543 CAMBRIAN EXPLOSION begins
• 480-250 million-
• Cambrian - 1st vertebrates appear (Jawless
  Fishes)
• Ordovician- 1st Mass Extinction
• Silurian- 1st land plants are ferns and mosses
  (non-vascular)
• 1st land animals are amphibians and reptiles
• 1st insects appear
• 1st flowering land plants (vascular)
• 250 million- PERMIAN EXTINCTION (95 extinct) and
  Pangaea forms (very dry, arid LARGE land mass)