(a) How many million year ago, gigantic reptiles used to dominate on earth ? Give their common name and also mention the period and year in which they were predominanat on earth. (b) Why did these gigantic reptiles disappear from the earth in a short duration ? (c ) Name the most advanced living reptiles. List atleast two characters in which they resemble in mammals.

(a) How many million year ago, gigantic reptiles used to dominate on e

1.	(a) How many million year ago, gigantic reptiles used to dominate on earth ? Give their common name and also mention the period and year in which they were predominanat on earth. (b) Why did these gigantic reptiles disappear from the earth in a short duration ? (c ) Name the most advanced living reptiles. List atleast two characters in which they resemble in mammals.
Answer» (a) About 200 million years ago, gigantic reptiles, commonly called dinosaurs ruled the earth. They were predominant in Jurassic period of Merozoic ear. (b) Refer to article (c ) Crocodiles and alligators are the most advanced living reptiles. The two characters in which they resemble the mammals are `:` (i) Thecodont teeth (ii) Four-chambered heart.