The First Mammals Evolved From Mammal Like Reptiles At The End Of The Triassic Period

1050 Words Nov 13th, 2015 5 Pages
The first mammals evolved from mammal-like reptiles at the end of the triassic period. Therapsids, or mammal-like reptiles, is an order of reptiles that lived in the Permian and Triassic Periods before going extinct in the mid Jurassic Period. It is difficult for scientist to determine when the divide between therapsids and mammals occurred. Early mammals had small, mouselike forms. Very few were large, because dinosaurs were the unquestioned dominant land animals on earth. The ecological niche they inhabited included eating plants, insects, and small lizards. They lived in trees and hunted at night to avoid dinosaurs, who hunted in the daytime. They walked on four legs like mice. These mammals had the characteristics of all mammals, such as being warm blooded and females producing milk for their young. The first mammals evolved from mammal-like reptiles at the end of the triassic period. Therapsids, or mammal-like reptiles, is an order of reptiles that lived in the Permian and Triassic Periods before going extinct in the mid Jurassic Period. It is difficult for scientist to determine when the divide between therapsids and mammals occurred. Early mammals had small, mouselike forms. Very few were large, because dinosaurs were the unquestioned dominant land animals on earth. The ecological niche they inhabited included eating plants, insects, and small lizards. They lived in trees and hunted at night to avoid dinosaurs, who hunted in the daytime. They walked on four legs…

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