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The first mammals were small and furred, and resembled rats or shrews. Megazostrodon was one of the earliest mammals. Though mammals appeared on Earth about 200 million years ago, they became common only after the extinction of dinosaurs. |
Early mammals were inauspicious creatures. The first mammal-like forms appear in the fossil record during the late Triassic period, about 225 million years ago. They were small, superficially shrew-like forms, some no longer than a few centimeters. In the shadow of the dinosaurs — a group that coincidentally also made its first appearance in the late Triassic — the early mammals were certainly less than imposing. Throughout the Mesozoic period — for over 160 million years — the largest mammal was no bigger than a ground hog. Moreover, the many wondrous and sometimes bizarre mammals we know today — such as the whales, bats, elephants, and scaly pangolins — were not part of the Mesozoic and early Cenozoic scene.
Credit: Science Direct
Picture Credit : Google
