![]() Birds have between 5 and 8 free caudal vertebrae. The free vertebrae immediately following the fused sacro-caudal vertebrae of the synsacrum are known as the caudal vertebrae. Similar to the sacrum of mammals, the synsacrum lacks the distinct disc shape of cervical and thoracic vertebrae. When not in flight, this structure provides the main support for the rest of the body. The synsacrum consists of one thoracic, six lumbar, two sacral, and five sacro-caudal vertebrae fused into one ossified structure that then fuse with the ilium. Note that the caudal vertebrae (5–10) are not fused in this diagram but can be in certain species. ĭiagram of a general bird pelvic girdle skeleton including the lower vertebral column sections. Anterior thoracic vertebrae are fused in many birds and articulate with the notarium of the pectoral girdle. The thoracic vertebrae number between 5 and 10, and the first thoracic vertebra is distinguishable due to the fusion of its attached rib to the sternum while the ribs of cervical vertebrae are free. Data from various studies suggest that the main reason for head-bobbing in some birds is for the stabilization of their surroundings, although it is uncertain why some but not all bird orders show head-bob. ![]() Head-bobbing is synchronous with the feet as the head moves in accordance with the rest of the body. Head-bobbing is an optokinetic response which stabilizes a bird's surroundings as it alternates between a thrust phase and a hold phase. The neck plays a role in head-bobbing which is present in at least 8 out of 27 orders of birds, including Columbiformes, Galliformes, and Gruiformes. Most birds have about three times as many neck vertebrae as humans, which allows for increased stability during fast movements such as flying, landing, and taking-off. A flexible neck allows many birds with immobile eyes to move their head more productively and center their sight on objects that are close or far in distance. The neck of a bird is composed of many cervical vertebrae enabling birds to have increased flexibility. This vertebra (C1) is called the atlas which articulates with the occipital condyles of the skull and lacks the foramen typical of most vertebrae. All cervical vertebrae have ribs attached except the first one. The cervical vertebrae provide structural support to the neck and number between 8 and as many as 25 vertebrae in certain swan species ( Cygninae) and other long-necked birds. The vertebral column is divided into five sections of vertebrae: Sections of the vertebral column in anatomical bird diagrams Color The species included are as follows: Top row (left to right) Struthio camelus and Sagittarius serpentarius (formerly Gypogeranus serpentarius) Bottom row (left to right) Megascops choliba decussatus (formerly known as Strix decussata) and Falco rusticolus islandus (formerly Falco islandus). It falls off once the egg has been penetrated.Ĭollage of bird anatomical illustrations with the different vertebral sections color-coded across various species. The beaks of many baby birds have a projection called an egg tooth, which facilitates their exit from the amniotic egg. Birds also lack teeth or even a true jaw and instead have a beak, which is far more lightweight. Because of this, birds usually have a smaller number of bones than other terrestrial vertebrates. One key adaptation is the fusing of bones into single ossifications, such as the pygostyle. ![]() It is extremely lightweight but strong enough to withstand the stresses of taking off, flying, and landing. The bird skeleton is highly adapted for flight. Flightless birds, such as ostriches and emus, have pneumatized femurs and, in the case of the emu, pneumatized cervical vertebrae. Penguins, loons, and puffins are without pneumatized bones entirely. The bones of diving birds are often less hollow than those of non-diving species. ![]() Respiratory air sacs often form air pockets within the semi-hollow bones of the bird's skeleton. The number of hollow bones varies among species, though large gliding and soaring birds tend to have the most. Birds have many bones that are hollow ( pneumatized) with criss-crossing struts or trusses for structural strength.
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