What are the characteristics of the skeleton of mammals?

Despite the large difference in size and appearance of mammals, their skeletons have a similar structure, which explains their origin from the same ancestor. So, in all terrestrial species of this class, the limbs are located vertically in relation to the vertebral organ, and not like in reptiles or amphibians, in which they move to the side. In mammals, only the lower jaw moves. The spine is divided into 5 sections with different vertebrae, the number of which in the cervical spine is always seven.