Mammal

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One example is the relationship between early reptiles and later mammals, the so-called mammalian reptiles. 350 million years ago the world was full of reptiles, but no mammals. Mammals appeared by 250 million years ago. (Fossil reptiles are easily distinguished from fossil mammals by the complexity of the skeleton features including the characteristics of the teeth and the skull.) About 275 million years ago, its form is a skeleton between reptiles and mammals It seems to be between features. In some cases, intermediate animals are not clearly classified as reptiles or mammals. Reptiles such as these mammals will become fewer reptiles and more mammals over time. And they no longer lose association between the two forms. And they happen to be on the right side of the time

Before discussing how the first mammal evolved it was useful to define the differences between mammals and other animals, especially reptiles. A female mammal has a mammary gland that gives birth to a child. All mammals have hair or fur at at least some stages of their life cycle and all mammals have warm blood (endothermic) metabolism. For fossil records, paleontologists can distinguish between ancestral mammals and ancestral reptiles by the shape of the skull and neck bone, and the presence of two small bones in the inner ear of the mammal. )

Mammalian skeletal system has many unique features. Mammalian jaw consists of only one bone, tibia only. The vertebrae of other vertebrates consist of bones. In mammals, the skull is connected to the skull with a skull, but in other vertebrates, the rectangular bone of the jaw is connected to the bone of the skull joint. These bones are found in mammals, but they have been modified to act audibly and form bones in the middle ear. Other vertebrates have only one middle ear bone and tibia. There are three types of mammals, hammerbone, anvil, and tibia. The hammer bone begins with the joint bone and the anvil bone starts from the square bone. This arrangement of jaw and ear bones will help distinguish fossilized mammals from other synapse fossils