Question

Evolution of flora and fauna through geological timescale

Answer 1

Evolution of flora:---Different kinds of algae were present in Cambrian. Marine algae were abundant in Ordovician. Origin of bryophytes took place before the appearance of vascular plants (pteridophytes, gymnosperms and angiosperms). Origin of vascular plants took place in Silurian. First gymnosperms appeared in Devonian. Origin of first seed plants occurred in Carboniferous. Angiosperms appeared in Cretaceous. Angiosperms diversified in Miocene and their adaptive radiation occurred in Pliocene.Origin of vertebrates took place in Ordovician period in the form of ostracoderms (jawless vertebrates related to cyclostomes). In fact ostracoderms were small, jawless bony fish-like forms. After the origin of ostracoderms acanthodians (the earliest known vertebrates with lower jaws) appeared in Silurian. Placoderms (the ancient gnathostomes- jawed vertebrates) arose in Silurian.

Placoderms were in fact jawed fishes. Origin of amphibians occurred in Devonian. Reptiles appeared in Carboniferous. Origin of dinosaurs and mammals took place in Triassic. Toothed birds (first birds) appeared in Jurassic. Thus origin of fishes took place first, with amphibians next, followed by reptiles, then mammals and birds.
Evolution of fauna:---Origin of vertebrates took place in Ordovician period in the form of ostracoderms (jawless vertebrates related to cyclostomes). In fact ostracoderms were small, jawless bony fish-like forms. After the origin of ostracoderms acanthodians (the earliest known vertebrates with lower jaws) appeared in Silurian. Placoderms (the ancient gnathostomes- jawed vertebrates) arose in Silurian.

Answer 2

Explanation:

Evolution of Plants:

Marine algae were abundant in Ordovician. Origin of bryophytes took place before the appearance of vascular plants (pteridophytes, gymnosperms and angiosperms). ... Angiosperms appeared in Cretaceous. Angiosperms diversified in Miocene and their adaptive radiation occurred in Pliocene