Geologic Periods
How long ago did the Hadean Eon span? 4.6 BYA - 4.0 BYA
When did eukaryotic cells originate? 2.1 BYA
When did the Devonian Period occur? 416 - 359 MYA
When did the Cretaceous Period occur? 145.5-65.5 MYA
What caused atmospheric oxygen levels to rise at the beginning of the Proterozoic Eon? Photosynthesis by bacteria
When did the first evidence of life appear, in the form of stromatolites? 3.5 BYA
When did the Paleozoic Era span? 542-251 MYA
What kind of surface did the Earth have during the Hadean Eon? Hot, molten surface
How long ago did the Archean Eon span? 4.0 BYA - 2.4 BYA
What characterized the Earth's surface during the Hadean Eon? Asteroid impacts and volcanoes
Around when did the actual origin of life likely occur? Around 3.9 BYA
How long ago did the Proterozoic Eon span? 2.5 BYA - 542 MYA
During what period did the rise of multicellular eukaryotes occur? Ediacaran Fauna Period
What types of organisms characterized the Ediacaran Fauna? Jellies, anemones, sponges
What kind of organisms were Ediacaran Fauna organisms? Soft-bodied organisms
When did the Cambrian period occur? 542-488 MYA
Approximately what fraction of Earth's history does the Phanerozoic Eon represent? Around a ninth
How long ago did the Phanerozoic Eon begin? 542 MYA- present
What is notable about the Phanerozoic Eon in terms of life? Most of the history of multicellular organisms
What major event is associated with the Cambrian period? Cambrian explosion
What periods occurred in the Cenozoic Era? Paleogene period
Neogene period
Quaternary period
What happened during the Cambrian explosion? Huge increase in diversity and disparity
What is significant about the animal phyla during the Cambrian period? Every extant phylum was present, plus some extinct
What contributed to the Cambrian explosion? Increased oxygen, bilateral symmetry, hard body structures
What does "diversity" refer to in the context of species? Number of species on Earth
What is the Burgess Shale known for? Cambrian animals
What does "disparity" refer to in the context of species? Variety of body plans
When did the Silurian period occur? 444-416 MYA
When did the Ordovician Period occur? 488-444 MYA
What kind of fishes appeared during the Ordovician Period? Ostracoderms (armored jawless fishes)
What type of animals were abundant during the Ordovician Period? Lots of trilobites
What kind of armored fish appeared during the Devonian Period? Placoderms
What kind of fishes appeared during the Silurian Period? Freshwater jawless fishes
What evidence of life on land is present from the Silurian period? Fungi, arachnids, centipedes
What kind of fishes diversified during the Carboniferous period? Ray finned fishes
What animals first began moving onto land in the Devonian Period? First tetrapods
What kind of plants appeared during the Devonian Period? Ferns
When did the Carboniferous period occur? 359-299 MYA
What kind of forests developed during the Carboniferous period? Swampy forests
When did the Permian period occur? 299-251 MYA
What is the evolutionary significance of the tetrapods during the Carboniferous period? Origin of amniotes
What environmental change occurred during the Carboniferous period? Polar ice lead to sea level drop
What is the geological significance of the swampy forests in the Carboniferous period? Due to lots of fossil fuels
What mass extinction event occurred at the end of the Permian period? Permian/Triassic
What happened to reptiles during the Permian period? Reptiles diversify
What kind of plants became dominant during the Permian period? Gymnosperms
What animals are included in the amniotes that originated during the Carboniferous period? Reptiles, birds, mammals
When was the Cambrian period? 542-488 MYA
Which marine species were affected by the Permian/Triassic extinction? Trilobites, echinoderms, brachiopods, some fishes
What is significant about the Permian/Triassic extinction event? Biggest mass extinction in Earth’s history
When was the Ordovician period? 488-444 MYA
What are the possible causes of the Permian/Triassic extinction? Volcanic activity and methanogenic bacteria
What kind of species were mostly affected by the Permian/Triassic extinction event? Mostly marine species
What percentage of species went extinct during the Permian/Triassic extinction event? 90%
What was the result of the volcanic activity and methanogenic bacteria that caused the Permian/Triassic extinction? Resulting in climate change
What periods occurred in the Paleozoic Era? Cambrian period
Ordovician period
Silurian period
Devonian period
Carboniferous period
Permian period
How long ago did the Triassic period occur? 251-199.6 MYA
What new groups of animals originated during the Triassic period? Dinosaurs and mammals
Which periods are included in the Mesozoic era? Triassic, Jurassic, and Cretaceous
When did the Jurassic Period occur? 199.6-145.5 MYA
What periods occurred in the Mesozoic Era? Triassic period
Jurassic period
Cretaceous period
What percentage of species went extinct during the Cretaceous/Paleogene extinction? 80%
Which famous dinosaurs lived during the Jurassic period? Tyrannosaurus rex, triceratops, velociraptor, gallimimus
Are hominins our species? No
Which group of animals continued to diversify during the Jurassic period? Dinos
What is the name of the second biggest mass extinction? Cretaceous/Paleogene
What is the time frame of the Neogene period in MYA? 23 - 2.6 MYA
Which ancestors of humans appeared during the Neogene period? Hominins
What is the time frame of the Paleogene period in MYA? 65.5 - 23 MYA
How old are the La Brea Tar Pit animals? Less than 40k old
What is the time frame of the Quaternary period? 2.6 MYA to PRESENT
Approximately how long ago did Homo sapiens appear? 200k years ago
What is the possible cause of the cretaceous/paleogene mass extinction? Impacts by objects from space that caused climate change
Which group of animals diversified during the Paleogene period? Mammals, birds, flowering plants, pollinating insects
Which type of dinosaurs went extinct during the Cretaceous/Paleogene extinction? Non-avian dinos
Which animals went extinct during the Cretaceous/Paleogene extinction? non-avian dinos, pterosaurs, mosasaurs, and many other species
What happened in the Triassic period in terms of the remaining life on Earth? Survivors of extinction spread and flourished
Which flying reptiles lived during the Jurassic period? Pterosaurs
What marine reptiles existed in the seas during the Jurassic period? Plesiosaurs and ichthyosaurs
What was the name of the first bird species, that originated during the Jurassic period? Archaeopteryx
What animals diversified during the Jurassic period? Dinosaurs!: Sauropods, brachiosaurs, and stegosaurs