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The Triassic period (248 - 206 million years ago) followed the biggest mass extinction in the history of the Earth, the Permian extinction. This left the Earth relatively unpoplated (especially the seas) and ready for new life. During the Triassic period, the first dinosaurs and the first mammals appeared. Many plant families were culled; giant club mosses and horsetails also went extinct during the late Permian, and new forms evolved during the Triassic. The Triassic was the beginning of a boom in conifers and cycadophytes.
Horsetails were an important source of nutrition for plant-eating dinosaurs. These primitive vascular plants were fast-growing and resilient (they could propagate using underground runners which a grazing dinosaur wouldn't eat). This meant that a hungry dinosaur could eat the plant without killing it, since the plant would regrow from the rhizome (the underground stem).
Seed ferns like Glossopteris and early species of gymnosperms (seed plants, such as the evergreens, in which the seeds are not enclosed) dominated the early Triassic terrain. Cycads, cycadeoids (like Pterophyllum, Zamites, and Williamsonia) and bennettitaleans, with tufts of tough, palm-like leaves and a woody trunk, were abundant in the Triassic. Also around were liverworts, mosses, smaller horsetails, club mosses, ferns, tree ferns (like Psaronius and glossopterids), ginkgophytes (like Baierophyllites), Filincophytes (like Macrotaeniopteris), Araucaria (the monkey puzzle tree), Bjuvia, Filincophytes (like Clathopteris), Lycopsids (like Sigillaria) and yews. "Cheiroleps" (conifers from the group Cheirolepidiaceae) dominated the northern latitudes during the Triassic period.
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.
Relatively small dinosaurs evolved during the mid Triassic period. The early plant-eating dinosaurs included Fabrosaurids (like Lesothosaurus), Heterodontosaurids (like Heterodontosaurus) and prosauropods (like Plateosaurus). They were fast-moving plant-eaters that probably ate low-lying plants. Many, like Plateosaurus, may have been able to rear up on two legs to reach taller vegetation.
Late in the Triassic Period:
The supercontinent of Pangaea began to split up towards the end of the Triassic period. Laurasia (the northern continent) was dominated by conifers (like Araucarioxylon), other seed plants and ferns; Gondwanaland (the southern continent) was dominated by the seed fern Dicroidium (a corytosperm). Other late Triassic plants included Peltasperms, Corystosperms, Wielandiella, and Sanmiguelia.
Glossopteris, a tree-like seed fern (Pteriosperm) from the Permian through the Triassic Period. It had tongue-shaped leaves and was about 12 ft (3.7 m) tall. Glossopteris was a dominant plant in Gondwana (the southern supercontinent) early in the Triassic period.
There was a minor extinction toward the end of the Triassic, about 208-213 million years ago. 35% of all animal families died out, including labyrinthodont amphibians, conodonts, and all
marine reptiles except ichthyosaurs. Many plants also went extinct, including the glossopterids (a group of tree ferns). No one knows what caused this late Triassic extinction; possibilities include global cooling or an asteroid impact.
PANGAEA AND WEATHER DURING THE TRIASSIC
The dinosaurs evolved early in the Mesozoic Era, during the Triassic period (about 228 million years ago). At the start of the Mesozoic Era, the continents of the Earth were jammed together into the supercontinent of Pangaea; this land mass had a hot, dry interior with many deserts. The polar regions were moist and temperate.
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