Notarium

Last updated
Skeleton of a mounted Pteranodon, showing the notarium between the shoulder blades UCMP Pteranodon dorsal body.JPG
Skeleton of a mounted Pteranodon , showing the notarium between the shoulder blades

Notarium or os dorsale is a bone consisting of the fused vertebra of the shoulder in birds and some pterosaurs. The structure helps brace the chest against the forces generated by the wings. In birds, the vertebrae are only in contact with adjacent vertebrae and ribs, while in some pterosaurs 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 and vertebral column (though in species with clavicles, 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, Columbidae, Tinamidae, Podicipedidae, Phalacrocoracidae, Threskiornithidae, Phoenicopteridae, Falconidae, Gruidae, Aramidae, Psophiidae, Rhinochetidae, Eurypygidae, Mesitornithidae, Pteroclididae, Opisthocomidae and Steatornithidae. It contains 2-6 vertebrae. It probably evolved at least 10 times independently in birds. [1]

Related Research Articles

<span class="mw-page-title-main">Pterosaur</span> Flying reptiles of the extinct clade or order Pterosauria

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. Pterosaurs are the earliest vertebrates known to have evolved powered flight. Their wings were formed by a membrane of skin, muscle, and other tissues stretching from the ankles to a dramatically lengthened fourth finger.

<span class="mw-page-title-main">Rib</span> Long bone in vertebrates that protects vital respiratory and cardiovascular organs

In vertebrate anatomy, ribs are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the chest cavity. They serve to protect the lungs, heart, and other internal organs of the thorax. In some animals, especially snakes, ribs may provide support and protection for the entire body.

<span class="mw-page-title-main">Clavicle</span> Long bone that serves as a strut between the scapula and the sternum

The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the right. The clavicle is the only long bone in the body that lies horizontally. Together with the shoulder blade, it makes up the shoulder girdle. It is a palpable bone and, in people who have less fat in this region, the location of the bone is clearly visible. It receives its name from Latin clavicula 'little key' because the bone rotates along its axis like a key when the shoulder is abducted. The clavicle is the most commonly fractured bone. It can easily be fractured by impacts to the shoulder from the force of falling on outstretched arms or by a direct hit.

<i>Ornithodesmus</i> Extinct genus of dinosaurs

Ornithodesmus is a genus of small, dromaeosaurid dinosaur from the Isle of Wight in England, dating to about 125 million years ago. The name was originally assigned to a bird-like sacrum, initially believed to come from a bird and subsequently identified as a pterosaur. More complete pterosaur remains were later assigned to Ornithodesmus, until recently a detailed analysis determined that the original specimen in fact came from a small theropod, specifically a dromaeosaur, making it one of the first dromaeosaurs known to science. All pterosaurian material previously assigned to this genus has been renamed Istiodactylus.

Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight. Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capable of very high metabolic rates and oxygen supply, permit the bird to fly. The development of a beak has led to evolution of a specially adapted digestive system.

<i>Zhejiangopterus</i> Genus of azhdarchid pterosaur from the Late Cretaceous

Zhejiangopterus is a genus of azhdarchid pterosaur known from one species, which lived in China during the late Cretaceous Period. The genus was named in 1994 by Chinese paleontologists Cai Zhengquan and Wei Feng. The type species is Zhejiangopterus linhaiensis. The genus name refers to Zhejiang Province and a Latinized Greek pteron, "wing". The specific name refers to the city of Linhai.

<i>Istiodactylus</i> Genus of istiodactylid pterosaur from the Early Cretaceous

Istiodactylus is a genus of pterosaur that lived during the Early Cretaceous period, about 120 million years ago. The first fossil was discovered on the English Isle of Wight in 1887, and in 1901 became the holotype specimen of a new species, O. latidens, in the genus Ornithodesmus. This species was moved to its own genus, Istiodactylus, in 2001; this name is Greek for "sail finger". More specimens were described in 1913, and Istiodactylus was the only pterosaur known from three-dimensionally preserved fossils for much of the 20th century. In 2006, a species from China, I. sinensis, was assigned to Istiodactylus, but it has also been suggested to belong to a different genus.

<i>Phosphatodraco</i> Late Cretaceous genus of pterosaur

Phosphatodraco is a genus of azhdarchid pterosaur that lived during the Late Cretaceous of what is now Morocco. In 2000, a pterosaur specimen consisting of five cervical (neck) vertebrae was discovered in the Ouled Abdoun Phosphatic Basin. The specimen was made the holotype of the new genus and species Phosphatodraco mauritanicus in 2003; the genus name means "dragon from the phosphates", and the specific name refers to the region of Mauretania. Phosphatodraco was the first Late Cretaceous pterosaur known from North Africa, and the second pterosaur genus described from Morocco. It is one of the only known azhdarchids preserving a relatively complete neck, and was one of the last known pterosaurs. Additional cervical vertebrae have since been assigned to the genus, and it has been suggested that fossils of the pterosaur Tethydraco represent wing elements of Phosphatodraco.

<i>Huanhepterus</i> Genus of ctenochasmatid pterosaur from the Early Cretaceous

Huanhepterus is an extinct genus of ctenochasmatid pterodactyloid pterosaur from the Early Cretaceous period of what is now Qingyang, Gansu, China.

<i>Santanadactylus</i> Genus of pteranodontoid pterosaur from the Early Cretaceous

Santanadactylus was a genus of pterodactyloid pterosaur from the Albian-age Romualdo Member of the Upper Cretaceous Santana Formation, of Barra do Jardim, Araripe Plateau, Ceará State, Brazil. Four species have been named, but today are no considered congeneric with each other. It was a rather large pterosaur.

<span class="mw-page-title-main">Gastralia</span>

Gastralia are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In these reptiles, gastralia provide support for the abdomen and attachment sites for abdominal muscles.

<i>Zhenyuanopterus</i> Genus of boreopterid pterosaur from the Early Cretaceous

Zhenyuanopterus is a genus of boreopterid pterosaur which is known from Lower Cretaceous Yixian Formation of Liaoning, China. It contains one species, Zhenyuanopterus longirostris, which was first described and named by Lü Junchang.

<span class="mw-page-title-main">Poposauroidea</span> Extinct clade of reptiles

Poposauroidea is a clade of advanced pseudosuchians. It includes poposaurids, shuvosaurids, ctenosauriscids, and other unusual pseudosuchians such as Qianosuchus and Lotosaurus. It excludes most large predatory quadrupedal "rauisuchians" such as rauisuchids and "prestosuchids". Those reptiles are now allied with crocodylomorphs in a clade known as Loricata, which is the sister taxon to the poposauroids in the clade Paracrocodylomorpha. Although it was first formally defined in 2007, the name "Poposauroidea" has been used for many years. The group has been referred to as Poposauridae by some authors, although this name is often used more narrowly to refer to the family that includes Poposaurus and its close relatives.

<i>Cosesaurus</i> Extinct genus of reptiles

Cosesaurus is a genus of archosauromorph reptiles likely belonging to the family Tanystropheidae. It is known from fossil imprints of a single small skeleton, MGB V1, which was found in Muschelkalk outcrops near the municipalities of Mont-ral and Alcover in Spain. These outcrops are dated to the Ladinian age of the middle Triassic about 242 to 237 million years ago. The specimen is stored at the Museu Martorell, which is now part of the Museu de Ciències Naturals de Barcelona. The poor preservation and likely juvenile nature of the specimen has led to the anatomy of Cosesaurus being misidentified by several different sources. For example, Paul Ellenberger claimed that it was an ancestor to birds in the 1970s, while David Peters claimed that it was a pterosaur ancestor in 2000. Both of these claims contrast with mainstream scientific theories on the origins of either group, and other paleontologists who study the specimen are unable to find the features which Ellenberger or Peters reported to be present. The Ellenberger and Peters hypotheses are thus considered fringe theories with questionable scientific soundness due to their low reproducibility. Mainstream hypotheses for the relations of Cosesaurus generally agree that it is a "protorosaur", specifically a tanystropheid closely related to long-necked reptiles such as Macrocnemus, Tanytrachelos, Tanystropheus, or Langobardisaurus.

<span class="mw-page-title-main">Vertebral column</span> Bony structure found in vertebrates

The vertebral column, also known as the backbone or spine, is the core part of the axial skeleton in vertebrate animals. The vertebral column is the defining characteristic of vertebrate endoskeleton in which the notochord found in all chordates has been replaced by a segmented series of mineralized irregular bones called vertebrae, separated by fibrocartilaginous intervertebral discs. The dorsal portion of the vertebral column houses the spinal canal, a cavity formed by alignment of the neural arches that encloses and protects the spinal cord.

This glossary explains technical terms commonly employed in the description of dinosaur body fossils. Besides dinosaur-specific terms, it covers terms with wider usage, when these are of central importance in the study of dinosaurs or when their discussion in the context of dinosaurs is beneficial. The glossary does not cover ichnological and bone histological terms, nor does it cover measurements.

<span class="mw-page-title-main">Vertebra</span> Bone in the vertebral column

Each vertebra 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 spinal segment and the particular species.

Aphanosauria is an extinct group of reptiles distantly related to dinosaurs. They are at the base of a group known as Avemetatarsalia, one of two main branches of archosaurs. The other main branch, Pseudosuchia, includes modern crocodilians. Aphanosaurs possessed features from both groups, indicating that they are the oldest and most primitive known clade of avemetatarsalians, at least in terms of their position on the archosaur family tree. Other avemetatarsalians include the flying pterosaurs, small bipedal lagerpetids, herbivorous silesaurids, and the incredibly diverse dinosaurs, which survive to the present day in the form of birds. Aphanosauria is formally defined as the most inclusive clade containing Teleocrater rhadinus and Yarasuchus deccanensis but not Passer domesticus or Crocodylus niloticus. This group was first recognized during the description of Teleocrater. Although only known by a few genera, Aphanosaurs had a widespread distribution across Pangaea in the Middle Triassic. They were fairly slow quadrupedal long-necked carnivores, a biology more similar to basal archosaurs than to advanced avemetatarsalians such as pterosaurs, lagerpetids, and early dinosaurs. In addition, they seemingly possess 'crocodile-normal' ankles, showing that 'advanced mesotarsal' ankles were not basal to the whole clade of Avemetatarsalia. Nevertheless, they possessed elevated growth rates compared to their contemporaries, indicating that they grew quickly, more like birds than other modern reptiles. Despite superficially resembling lizards, the closest modern relatives of aphanosaurs are birds.

<i>Thalassodraco</i> Extinct genus of ophthalmosaurid ichthyosaur

Thalassodraco is an extinct genus of ophthalmosaurid ichthyosaur from the Late Jurassic (Tithonian) Kimmeridge Clay Formation of England. The type species, T. etchesi, was named in 2020, with the epithet in honour of the discoverer of the holotype, Steve Etches.

References

  1. Storer R. W. (1982). "Fused Thoracic Vertebrae in Birds: Their Occurrence and Possible Significance". Journal of the Yamashina Institute for Ornithology. 14: 86–95. doi: 10.3312/jyio1952.14.86 . Archived from the original on 2018-11-03.