Tuesday, 25 May 2021

The tertiary period started 63 million years ago

 The tertiary period started 63 million years ago 



 Gymnosperms predominant during : Coenozoic Era and Quarternary period.(1) Tertiary Period : This is the first period of coenozoic era. The tertiary period started 63 million years ago and ended just one million years back. The climate was warm earlier and later it was cooler. The tertiary period is divided into five epochs : 

(i) Palaeocene: It lasted for 17 million years. Angiosperms were modernised during this time. (ii) Eocene : It lasted for 22 million years. Woody ángiosperms developed during this epoch. (iii) Oligocene : It started 36 million years ago and ended 11 million years back. The woody angiosperms dispersed in broad areas.

 (iv) Miocene : It started 25 million years ago and. ended 13 million years back. The fossils of monocot plants were discovered from deposits of this age. Pliocene : This epoch started 13 million years (v) ago and ended one million years back. The monocots and herbaceous plants spreaded to large areas. 

(2) Quarternary Period: This is the latest period of coenozoic era. The quarternary period started just one million years ago and lasted till today. The climate has been varying so much. The quarternary period has an epoch, Pleistocene.

 The species development of herbaceous plants have been taking place during this period. On the basis of comparative morphology of living and fossil forms, two different views have been put forward regarding the origin of pteridophytes. Scott (1900), Bohin (1901), Church (1919), Fritsch (1916, 1945), Eames (1936), and Arnold (1947) believe 'in algal origin df pteridophytes.

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