1. LECTURE 4: PALEOZOIC ERA Cambrian/Ordovician Periods

2. STUDY THIS PICTURE! 2

4. What Life existed in the Early Cambrian Period (543 mya)?
Late Precambrian Period
Ediacaran Fauna
Limited Diversity
Early Cambrian Period ( 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

5. 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

6. Make a cladogram Lab?

8. What was the Cambrian Explosion?
most animals appear in a relatively BRIEF time in history (~ 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

9. 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)

10. What Trace Fossil marks the Beginning of the Cambrian Period?
Trichophycus pedum
Burrowing animal
No hard parts

11. 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!!

12. Burgess Shale Fauna

13. Canapaptsis
Hallucigenia
Wapatia

14. Pikaia (earliest chordate)

15. Anomalocaris
Wiwaxia
Opabinia

19. 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

20. What was the First Vertebrate
What was the First Vertebrate? First Jawless fish: Myllokunmingia 500 mya Ancestor to Living Jawless Fish (Lampreys)

21. 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

22. 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.

23. What did the Continents Look Like?
Continental Drift Animation
Continent Animation 600 mya to 50 mya

24. PALEOZOIC (543-245 mya) 543 billion- Ozone Layer forms
543 CAMBRIAN EXPLOSION begins
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)