| A | B |
|---|
| Paleozoic Era included what periods (oldest to youngest)? | Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian |
| Mesozoic Era included what periods (oldest to youngest)? | Triassic, Jurassic, Cretaceous |
| Cenozoic Era included what periods (oldest to youngest)? | Tertiary, Quaternary |
| About the Cambrian Period | (550-488) in Paleozoic. Continental masses broken up, shallow seas. First chordates, first vertebrates (Myllokumingia/Haikouichthys). Diversification of invertebrates. |
| About the Ordovician Period | (488-444) in Paleozoic. Global climate equable until sharp glaciation at end of period. First complex plants on land. Radiation of first jawless fishes (ostracoderms), some evidence of jawed fishes. Oldest craniates |
| About the Silurian Period | (444-416) in Paleozoic. Jawless fishes radiated, and jawed fishes now definitely known |
| About the Devonian Period | (416-359) in Paleozoic. The "Age of Fishes," and origins of tetrapods (350 mya), freshwater Chondrichthyes arrive |
| About the Carboniferous Period | (359-299) in Paleozoic. Major glaciation in 2nd half of period. Coal swamps prevalent. Diversification of jawed forms including shark-like and primitive bony fishes, also appearance of many modern jawless fishes. Appearance of amniotes (330 my) |
| About the Permian Period | (299-251), final period in Paleozoic Era. Pangea formed at the end, glaciation ceased. Amniotes radiated: diversification included ancestors of modern reptiles and mammals. Largest mass extinction at end. |
| About the Triassic Period | (251-200) in Mesozoic. No glaciation. First appearances include early dinosaurs and mammals (225 mya). Evolution of extant sharks occurred (210 mya) |
| About the Jurassic Period | (200-141) in Mesozoic. World continent began to break up, form Atlantic Ocean. Modern sharks and rays appear. Dinos diversified, mammals stayed small. First birds, lizards, and salamanders |
| About the Cretaceous Period | (141-65) in Mesozoic. Continents keep separating, breakup of southern continent Godwana. At the end of the period there was a mass extinction that claimed dinosaurs, marine reptiles and many marine inverts. |
| About the Tertiary Period | (65-5) in Cenozoic. Global climate was warm early on but later cooled. Arctic ice cap formed by the end and first grasslands appeared. Rapid diversification of teleost fishes, birds, and mammals |
| About the Quaternary Period | (5-now) in Cenozoic. Modern humans appeared. Extinction of lots of large mammals with human expansion. |
