relationship loss: part_of postzonal element (AAO:0000938)[AAO]

https://github.com/cmungall, https://github.com/alex-dececchi

http://upload.wikimedia.org/wikipedia/commons/1/12/Illu_thoracic_cage.jpg

While its developmental origins are similar to the ribs (from the myospetum and septum of the trunk region), it is often associated with the pectoral skeleton, due to both function and physical connections (i.e. the coracoid of archosaurs). It may be a single element or a series of smaller structure (sternebrae). Based on Kardong 2012. [PHENOSCAPE:ad].

in EMAPA and EHDAA2 this is part of the skeleton of pectoral girdle; the classic def of pectoral girdle (see WP) excludes the rib cage and sternum

Single element that constitutes the postzonal area of the pectoral girdle.[AAO]

uberon

breastbone

sternal

Fishes lack a sternum. (...) A sternum is absent in the first fossil tetrapods, but it is present in modern amphibians. (...) Thus, a sternum occurs in some modern amphibians, birds, mammals and archosaurs. However, its absence in the common ancestors to these groups means that it has arisen independently several times within the field of the midventral connective tissue.[well established][VHOG]

UBERON:0000975

It probably first evolved in early tetrapods as an extension of the pectoral girdle; it is not found in fish. In amphibians and reptiles it is typically a shield-shaped structure, often composed entirely of cartilage. It is absent in both turtles and snakes. In birds it is a relatively large bone and typically bears an enormous projecting keel to which the flight muscles are attached. Only in mammals does the sternum take on the elongated, segmented form seen in humans. In some mammals, such as opossums, the individual segments never fuse and remain separated by cartilagenous plates throughout life, in birds, either ratite (no keel or carina) or carinate (keel and carina present)

• pectoralis major
• sternooccipital muscle

• sternoclavicular joint

• true rib

• rectus abdominis muscle

• sternebra
• xiphoid process
• sternebral bone pre-cartilage condensation
• cartilage tissue of sternum