Rib cage
The rib cage is the arrangement of ribs attached to the vertebral column and sternum in the thorax of most vertebrates, that encloses and protects the heart and lungs. In humans, the rib cage, also known as the thoracic cage, is a bony and cartilaginous structure which surrounds the thoracic cavity and supports the shoulder girdle to form the core part of the human skeleton. A typical human rib cage consists of 24 ribs in 12 pairs, the sternum and xiphoid process, the costal cartilages, and the 12 thoracic vertebrae.
Hominid dental morphology evolution
Today, humans possess 32 permanent teeth with a dental formula of . This breaks down to two pairs of incisors, one pair of canines, two pairs of premolars, and three pairs of molars on each jaw. In modern day humans, incisors are generally spatulate with a single root while canines are also single rooted but are single cusped and conical. Premolars are bicuspid while molars are multi-cuspid. The upper molars have three roots while the lower molars have two roots.