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Eduncle posted an MCQ
October 19, 2019 • 17:36 pm 0 points
  • IIT JAM
  • Geology (GG)

Dicroidium is known from the

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    Eduncle Best Answer

    Dicroidium Flora - Middle to Late Triassic 245-208 Ma 
    cretaceous Rajmahal Formation and underlying Triassic Panchet Formation between 288–423.51 m.
    At the end of the Permian  and the start of the Triassic was a warm, wet time. There was a sudden appearance of new flora characterised by the first forked-frond Seed-ferns, Podocarp Conifers, Cycadophytes, ferns, Ginkgos. During this time the Glossopterids drop out of the fossil record. During the Triassic, the climate was changing to become hotter and drier, this led to the development of drought-resistant adaptations in some plants of the Middle and Late Triassic. The flora of this period is characterised by Dicroidium Flora.
    Dicroidium is a seed fern. It dominated the Gondwanan vegetation following the decline of another seed fern, Glossopteris, which had previously dominated the flora. Among the other plants present in the Dicroidium dominated vegetation were ferns, other seed ferns, ginkgophytes, cycads, conifers and horsetails. This vegetation type had many components that were already showing adaptations to arid conditions that pre-adapted the plants that were to survive and flourish in the later aridification of the Australian continent. Some of these adaptations were thickening of the cuticle and reduction of the surface area of the leaves, some to the point of becoming needles or spikes, phyllodes.

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