Search results
Results From The WOW.Com Content Network
In birds, the palatine bones remain separate, long the sides of the rear part of the upper jaw, and typically have a mobile articulation with the cranium. [4] There are numerous variations amongst mammals, amphibians and other species.
As typical for Galloanserae, the palatine bone ("Pa") is not expanded downwards. Skulls of a northern gannet (Morus bassanus, top) and various Charadriiformes (below). Note the expansion of the palatine bone visible inside the eye sockets in these Neoaves. Note also the supraorbital salt gland impressions of the Charadriiformes.
The leg bones of birds are the heaviest, contributing to a low center of gravity, which aids in flight. A bird's skeleton accounts for only about 5% of its total body weight. They have a greatly elongate tetradiate pelvis, similar to some reptiles. The hind limb has an intra-tarsal joint found also in some reptiles.
Other known remains include upper mandibles, a palatine bone, and tarsometatarsi. [2] The species has since been excavated from the Mare aux Songes swamp on Mauritius, from which subfossils of most of the other endemic bird species have been identified as well. [3]
In 2005 a cladistic analysis had found support in placing pseudo-toothed birds as the sister group to waterfowl. [2] Evidence for this comes from shared characteristics in the skull such as lack of a crest on the underside of the palatine bone and two condyles on the mandibular process of the quadrate bone, with the middle condyle beakwards of ...
However, in mammals, the bones have curved inward, creating the palatine process and thereby also forming part of the roof of the mouth. [8] Birds do not have a maxilla in the strict sense; the corresponding part of their beaks (mainly consisting of the premaxilla) is called "upper mandible". Cartilaginous fish, such as sharks, also lack a true ...
Palaeognathae (/ ˌ p æ l i ˈ ɒ ɡ n ə θ i /; from Ancient Greek παλαιός (palaiós) 'old' and γνάθος (gnáthos) 'jaw') is an infraclass [1] of birds, called paleognaths or palaeognaths, within the class Aves of the clade Archosauria.
This arch divides into a maxillary process and a mandibular process, giving rise to structures including the bones of the lower two-thirds of the face and the jaw. The maxillary process becomes the maxilla (or upper jaw, although there are large differences among animals [11]), and palate while the mandibular process becomes the mandible or lower jaw.