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| The Mesozoic Era (248 - 65 million years ago) Ages of the Mesozoic Era | ||||||||
| Triassic Period 248 - 206 mya First dinosaurs and mammals |
Jurassic Period 206-144 mya Many dinosaurs and the first birds |
Cretaceous Period 144-65 mya First flowering plants, the height of the dinosaurs. Ends in huge extinction. |
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| Early - Middle 248-227 mya |
Late 227-206 mya |
Early (Lias) 206-180 mya |
Middle (Dogger) 180-154 mya |
Late (Malm) 154-144 mya |
Early (Neocomian) 144-127 mya |
Middle (Gallic) 127-89 mya |
Late (Senonian) 89-65 mya |
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. This catastrophic extinction and continental rearrangement opened the way for the rise of the dinosaurs and mammals.
 Glossopteris, a tree-like plant from the Permian through the Triassic Period. It had tongue-shaped leaves and was about 12 ft (3.7 m) tall. Glossopteris was the dominant plant of Gondwana (the southern continent). |
, like Eozostrodon. Some scientists believe that mammals evolved from a group of extinct mammal-like reptiles, Theriodontia, which were Therapsids. These primitive mammals were tiny and are thought to have been nocturnal. The earliest-known turtle, Proganochelys, appeared during the late Triassic.
, frogs 
, salamanders, lizards (including sphenodonts & snakes), and pterosaurs 
first appeared in the Triassic. Also in the Triassic was Pseudosuchia, possible ancestor of Archaeopteryx. Aetosaurs like Desmatosuchus lived during the late Triassic period. Insects
began to undergo complete metamorphosis from larva through pupa to adult.
, marine reptiles, appeared.
 Leptocycas was a cycad, a primitive seed plant from the late Triassic period. It was a palm-like tree with a long, woody trunk and tough leaves. It lived in warm climates. This tree was about 4.8 ft (1.5 m) tall. |
and early species of gymnosperms (seed plants, such as the evergreens, in which the seeds are not enclosed) dominate the Triassic terrain. Cycads
, with tufts of tough, palm-like leaves and a woody trunk, appeared in the late Carboniferous and were abundant in the Triassic. Laurasia was dominated by conifers, other seed plants and ferns; Gondwanaland was dominated by Dicroidium.
at the beginning of the Triassic, 220 million years ago, decreased the amount of shoreline, formed mountains, and gave the interior of the supercontinent a dry, desert-like terrain. The polar regions were moist and temperate.
The Triassic period ended with a mass extinction accompanied by huge volcanic eruptions about 208-213 million years ago. The supercontinent Pangaea began to break apart. 35% of all animal families die out, including virtually all labyrinthodont amphibians, conodonts, and all
marine reptiles except ichthyosaurs. Most synapsids, which had dominated the Permian and early Triassic, went extinct (except for the mammals). Most of the early, primitive dinosaurs also went extinct, but other, more adaptive dinosaurs evolved in the Jurassic.
No one is certain what caused this late Triassic extinction; possibilities include global cooling or an asteroid impact. A 210 million-year-old meteor cratersurrounding Manicouagan Reservoir, Quebec, Canada, may be the remains of the culprit.
This extinction allowed the dinosaurs to expand into many niches that were now unoccupied. Dinosaurs would become increasingly dominant, abundant and diverse, and remained that way for the next 150 million years.
Triassic Printout:
Triassic animal printouts
| The Mesozoic Era (248 - 65 million years ago) Ages of the Mesozoic Era | ||||||||
| Triassic Period 248 - 206 mya First dinosaurs and mammals |
Jurassic Period 206-144 mya Many dinosaurs and the first birds |
Cretaceous Period 144-65 mya First flowering plants, the height of the dinosaurs. Ends in huge extinction. |
||||||
| Early - Middle 248-227 mya |
Late 227-206 mya |
Early (Lias) 206-180 mya |
Middle (Dogger) 180-154 mya |
Late (Malm) 154-144 mya |
Early (Neocomian) 144-127 mya |
Middle (Gallic) 127-89 mya |
Late (Senonian) 89-65 mya |
|
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