The crocodile is a kind of animal that we are familiar with. It is very large in size and quite fierce in character. They belong to the phylum Chordata, which is vertebrates. Although mammals are also vertebrates, not all vertebrates are mammals. There are many other classes of vertebrates. Crocodiles belong to the class Reptilia, so they are reptiles. Reptiles and mammals are two different animals, and there is no intersection between them, so if one animal belongs to one, it can not belong to the other. The crocodile belongs to a reptile and can't be a mammal. Mammals are more advanced than reptiles, and most of them are evolved from reptiles and have more advanced body structure.
Crocodiles differ from mammals in some key features. For example, from the appearance characteristics, crocodiles have scales on their bodies, while most mammals do not, and some mammals have fur on their bodies. For example, from the point of view of body temperature, crocodiles belong to poikilothermic animals, body temperature is not constant; While mammals are endotherms. Also, from the point of view of reproductive methods, crocodiles use the way of oviparous reproduction; Mammals, on the other hand, are viviparous and have a period of lactation.
Crocodiles live mainly in various freshwater basins, such as rivers and lakes. Most of them are distributed in the freshwater basins of tropical and subtropical latitudes. For example, Nile crocodiles living in Africa live in the Nile River, which is a freshwater river at a relatively low latitude. However, there are also some species living near the beach, sometimes into the ocean activities, such crocodiles are relatively small, but there are some, such as American crocodiles.
