The first life forms on Earth did not require oxygen and included single-celled organisms like cyanobacteria. Around 2.5 billion years ago, cyanobacteria that performed photosynthesis began producing oxygen as a byproduct, leading to its accumulation in the atmosphere. During the Cambrian period, the dominant forms of life were trilobites and brachiopods, while cephalopods were the first large predators. Various plants and animals evolved and diversified over the Paleozoic era, including fish, amphibians, and reptiles. By the late Paleozoic, the continents had collided to form the supercontinent Pangaea surrounded by a global ocean.

1. First Life The first life forms on Earth did not need oxygen. Who or what were these organisms? How about _________ !!!!!!!!!!!!!!!! _________ are not complete organisms. They need other organisms to provide nutrients to live SO!!!!!!!!!!!!!!!!!

2. 2.5 b.y.a. Oxygen build up primarily due to organisms that perform photosynthesis. These photosynthetic organisms are called _________ . Today cyanobacteria live in all green plants and are called? _________

3. Most of the first oxygen reacted with iron forming _________ (rust). Once the available iron finished reacting, oxygen began to accumulate in the atmosphere.

4. _________ began to accumulate in the atmosphere about 2.5 billion years ago. Ocean dwelling organism appeared in the fossil record about 540 million years ago (m.y.a.).

5. Precambrian Fossils _________ – are layered mounts of calcium carbonate, which are the remains of material deposited by algae.

6. Paleozoic Era: Life Explodes The Paleozoic ear is made of several periods including: Permian – youngest period Pennsylvanian Mississippian Devonian Silurian Ordovician Cambrian – oldest period

7. Early Paleozoic History During the Cambrian, Ordovician, and Silurian periods, the vast southern continent of _________ included: South America Africa Australia Antarctica India And perhaps China

8. North America was most likely on or near the equator. had no living things, plant or animal. Later on North America collides with Africa beginning the formation of the Appalachian Mountains and continues for 200 million years.

9. By the Silurian period, shallow seas or epicontinental seas covered much of North America. Many barrier reefs prevented circulation between the shallow marine basins and the open ocean. As the water evaporated salt and gypsum deposits formed.

10. _________ 2.7 b.y.a We now have the basic part to make all forms of life We just need to make things more and more complex _________ must adjust to do different kinds of jobs

11. What is the name of the 1 celled life form in the oceans? _________ represents all animal life to come _________ represents all plant life to come Plankton – 1.8 b.y.a.

12. Colonial organisms _________ critters that are not very specialized _________ _________ - (polyps) _________

13. Early Paleozoic Life Life at this time is restricted to the oceans. All forms of life were invertebrates. 1- _________ – bottom dwelling scavengers. They occurred in more than 600 types. They were the _________ form of life at this time.

14. Paleozoic Era - Cambrian period Dominant form of life is the trilobite Body segments Head shield Tail shield

15. 2 – _________ – these shelled organisms replace trilobites as the dominant form of life. Except for one species, brachiopods are extinct today. Their larvae were free swimming, but like oysters and clams, these shelled animals were attached to the ocean floor.

16. Paleozoic Era - Cambrian period brachiopods are present [ forerunner to the _________ ]

17. 3 – _________ – cousin to the octopus and squid. These highly mobile _________ were the major predator of the time. Cephalopods were the first large animal on Earth. By the end of the Ordovician many organism were able to secret material to form hard parts such as an exoskeleton.

18. Paleozoic Era –Ordovician 505 – 440 m.y.a. cephalopods ( _________ ) oldest one is the _________

19. Late Paleozoic The tectonic reorganization of Earth’s landmasses into one supercontinent called _________ .

20. Late Paleozoic History North America collides with Africa closing the narrow sea that separated them. As this collision continues the rest of the Northern Hemisphere continents join them. This resulted in the formation of the northern continent of _________ . By the Permian, Gondwana has traveled north and collides with Laurasia. By the end of the Paleozoic _________ is formed.

21. Late Paleozoic Life Plants living at the water’s edge move onto the land. These plants were leafless vertical spikes about the size of your index finger. By the end of the Devonian Period (40 million years later) there were forests. The first forests were in _________ …..

22. _________ First primitive fish _________

23. Paleozoic Era – Silurian 440 – 410 m.y.a. Appearance of _________ water fish. 1st land critters appear and were????? _________ Including: _________ _________ _________ _________ _________

24. Paleozoic Era - Devonian Known as the AGE OF FISHES _________ _________ _________ _________ _________ all modern fish

25. Amphibians diversified on land because they had no major competitors. By the Pennsylvanian period large tropical swamps extended across North America, Europe, and Siberia. Coal deposits today resulted from these swamps.

26. Lobe fin became the ancestor of _________