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 unpopulated (especially the seas) and ready for a 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.
Modern-day cycads are the direct descendants of cycadophytes.
Triassic land plants included a diverse assortment of plants characteristic of the "Mesophyta" ("middle flora" - from Late Permian to Middle Cretaceous). Calamites-like forms were however still important, perhaps fulfilling the ecological role of bamboo today, with Neocalamites reaching fifteen meters in height. Ferns also continued to flourish and dominated Triassic floras.
Ferns flourished during the Triassic period.
The drier climate - especially the arid interior - encouraged the evergreen conifers and other gymnosperms, which reproduced by exposed seeds and wind pollination. These include conifers (including many modern families), pteridosperms, cycads, Bennettiales, and ginkgos. Xeromorphic (dry adapted) characteristics were common, such as scale-leaved conifers and thick-cuticle pteridosperms and cycads. Moister conditions meant plant life was more abundant in the coastal regions. There were also several main biotic provinces, determined perhaps by climatic factors.
The Laurasian Flora is made up of; a mixture of primitive conifers - Voltziaceae and Lebachiaceae - along with cycads, Bennettitales, ginkgos (especially in northern latitudes), ground and tree ferns, and sphenopsids. The conifers and ginkgos seem to have been medium-sized to large trees that formed diffuse canopies. The northern part of Pangea was lusher, with forests of tree-ferns and gingkoaleans, and forest-floors covered in luxuriant fern growth. Araucariaceae conifers were the predominate large trees in Laurasia, with primitive gingkoaleans (e.g. Sphenobaiera and Glossphyllum) and cycads as a lower story and underbrush. The equatorial region was less favourable for much of period and the forests down here were sparse, consisting of conifers especially Araucariaceae) and cycads. The situation improved during the late Triassic, with moist conditions that encouraged cynodont herbivores.
Suggested reconstruction of the various organs of a Triassic Telemachus conifer from present-day Antarctica. For a detailed explanation, see ‘‘Habit Reconstruction.’’ The figure of Thomas N. Taylor (;180 cm) is provided for scale. Excerpt from "Whole-Plant Concept and Environment Reconstruction of a Telemachus Conifer (Voltziales) from the Triassic of Antarctica. Published in 2013"
References :
Benjamin Bomfleur, Anne-Laure Decombeix, Ignacio H. Escapa, Andrew B. Schwendemann and Brian Axsmith.International Journal of Plant Sciences
Vol. 174, No. 3, Special Issue: Conceptual Advances in Fossil Plant Biology Edited by Gar Rothwell and Ruth Stockey (March/April 2013), pp. 425-444
Lexicon :
Conifers
They are cone-bearing seed plants with vascular tissue. All living conifers are woody plants, and most are trees. Typical examples include cedars, cypresses, firs, junipers, kauris, larches, pines, redwoods, spruces, and yews.
Cycadophytes
Cycads are seed plants with a very long fossil history that were formerly more abundant and more diverse than they are today. They typically have a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves.
Calamites
Calamites is a genus of extinct arborescent horsetails to which the modern horsetails are closely related. Unlike their herbaceous modern cousins, these plants were medium-sized trees, growing to heights of more than 30 meters. They were components of the understories of coal swamps of the Carboniferous Period.
Gymnosperm
The gymnosperms, also known as Acrogymnospermae, are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes. The term "gymnosperm" comes from the composite word in Greek: γυμνόσπερμος, literally meaning "naked seeds". The name is based on the unenclosed condition of their seeds.
Pollination
Pollination is the act of transferring pollen grains from the male anther of a flower to the female stigma. The goal of every living organism, including plants, is to create offspring for the next generation. One of the ways that plants can produce offspring is by making seeds.
Bennettitales
Bennettitales is an extinct order of seed plants that first appeared in the Permian period and became extinct in most areas toward the end of the Cretaceous, although some Bennettitales appear to have survived into Oligocene times in Tasmania and eastern Australia.
Pteridosperms
The term Pteridospermatophyta refers to several distinct polyphyletic groups of extinct seed-bearing plants. The earliest fossil evidence for plants of this type is the genus Elkinsia of the late Devonian age. They flourished particularly during the Carboniferous and Permian periods.
Xeromorphic
(of plants or plant parts) having characteristics that serve as protection against excessive loss of water
Voltziales
Voltziales is an extinct order of trees related to modern conifers. In the fossil record, the most common member of the order is Walchia, known originally for its leaf form genus, and the order is commonly called Walchian.
Lebachiaceae
Lebachia, a genus of extinct cone-bearing plants known from fossils of the Late Carboniferous and Early Permian epochs (from about 318 million to 271 million years ago). A tree of uncertain size with pinnately arranged side branches (like the barbs of a feather), Lebachia apparently had a growth habit similar to that of the present-day Norfolk Island pine. It bore both pollen-bearing and seed-bearing cones (the latter, as detached fossils, are called Gomphostrobus) at the ends of the side branches.
Laurasia
Laurasia, a portmanteau for Laurentia and Asia, was the more northern of two minor supercontinents that formed part of the Pangaea supercontinent from c. 425 million years ago to 200 Mya.