Notarium or os dorsale is a bone consisting of the fused

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

of the shoulder in

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

s and some

pterosaur Pterosaurs are an extinct clade of flying reptiles in the order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosaurs are the earli ...

s. The structure helps brace the

chest The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

against the forces generated by the wings. In birds, the vertebrae are only in contact with adjacent vertebrae and ribs, while in some

pterosaurs Pterosaurs are an extinct clade of flying reptiles in the Order (biology), order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosau ...

the notarium articulates with the scapula. This joint is unique among tetrapods, as in no other taxa is there a direct connection between the

pectoral girdle The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans, it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists o ...

and vertebral column (though in species with

clavicle The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...

s, the clavicle articulates with the sternum, which in turn is connected to the vertebrae via the ribs, allowing an indirect connection). Among birds, notarium is found among

Galliformes Galliformes is an order (biology), order of heavy-bodied ground-feeding birds that includes turkey (bird), turkeys, chickens, Old World quail, quail, and other landfowl. Gallinaceous birds, as they are called, are important in their ecosystems ...

Columbidae Columbidae is a bird Family (biology), family consisting of doves and pigeons. It is the only family in the Order (biology), order Columbiformes. These are stout-bodied birds with small heads, relatively short necks and slender bills that in ...

, Tinamidae, Podicipedidae,

Phalacrocoracidae Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the International Ornithologists' Union (IOU) ado ...

Threskiornithidae The family Threskiornithidae includes 36 species of large wading birds. The family has been traditionally classified into two subfamilies, the ibises and the spoonbills; however, recent genetic studies have cast doubt on this arrangement, and ha ...

Phoenicopteridae Flamingos or flamingoes () are a type of wading bird in the family Phoenicopteridae, which is the only extant family in the order Phoenicopteriformes. There are four flamingo species distributed throughout the Americas (including the Caribbe ...

Falconidae The falcons and caracaras are around 65 species of Diurnality, diurnal birds of prey that make up the family Falconidae (representing all extant species in the order (biology), order Falconiformes). The family likely originated in South America d ...

, Gruidae, Aramidae,

Psophiidae ''Psophia'' is a genus of birds restricted to the humid forests of the Amazon and Guiana Shield in South America. It is the only genus in the family Psophiidae. Birds in the genus are commonly known as trumpeters, due to the trumpeting or cackli ...

, Rhinochetidae, Eurypygidae,

Mesitornithidae The mesites (Mesitornithidae) are a family (biology), family of birds that are part of a clade (Columbimorphae) that include Columbiformes and Pterocliformes. They are somewhat small-bodied, Flightless bird, flightless or near flightless birds en ...

, Pteroclididae, Opisthocomidae and Steatornithidae. It contains 2-6 vertebrae. It probably evolved at least 10 times independently in birds.

References

External links

Glossary: N
// palaeos.com * * {{cite web , url=http://archosaurmusings.wordpress.com/2009/06/05/a-pelvis-at-the-front-the-notarium/ , title=A pelvis at the front – the notarium , website=Dave Hone's Archosaur Musings Pterosaur anatomy Bird anatomy