|
Empeirodytes
''Empeirodytes'' is an extinct genus of Plotopteridae, a family of large flightless bird known from the Late Eocene to the Early Miocene of the West Coast of the United States, British Columbia and Japan. Remains associated with ''Empeirodytes'' have been found in Oligocene rocks of the Ashiya Group, on the islands of Ainoshima and Kaijima, near Kitakyushu, Japan. History and Etymology In 2020, Ohashi Tomoyuki and Hasegawa Yoshikazu first described the remains of ''Empeirodytes okazakii'', assigning as holotype KMNH VP 600011, a partial left coracoid found in Oligocene-aged rocks of the Ashiya Group on the island of Ainoshima, Japan. They referred as paratype a right coracoid from the same horizon, discovered on the nearby Kaijima. Etymology The genus name, ''Empeirodytes'', is formed from the Greek prefix "''Empeiros''", meaning "proficient", and the suffix "-''dytes''", meaning "diver", referencing the adaptation towards wing-propelled diving exhibited by plotopterids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stenornis
''Stenornis'' is an extinct genus of Plotopteridae, a family of large-sized, flightless seabirds native from the North Pacific during the Paleogene and the earliest Neogene. The remains of ''Stenornis'' have been found in Oligocene rocks of the Jinnobaru Formation on Hikoshima and the Ashiya Group on Ainoshima, Japan. History and Etymology The first remain associated with ''Stenornis'', an isolated left coracoid, was collected in 1976 by Ota Masamichi on the Japanese island of Hikoshima, and described in 1979 as an indeterminate new species of plotopterid by Ota and Hasegawa Yoshikazu. In 1986, while describing the new genus ''Copepteryx'', Hasegawa and Storrs L. Olson tentatively referred that coracoid to the North American genus ''Tonsala'', of which the coracoid was then badly known, based on similarities found in then undescribed Japanese plotopterids. In 2020, a new analysis of the coracoid (KMNH VP 200003) from Hikoshima by Ohashi Tomoyuki and Hasegawa Yoshikazu led ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plotopteridae
Plotopteridae is an extinct family of flightless seabirds with uncertain placement, generally considered as member of order Suliformes. They exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant penguins. That they lived in the North Pacific, the other side of the world from the penguins, has led to them being described at times as the Northern Hemisphere's penguins, though they were not closely related. More recent studies have shown, however, that the shoulder-girdle, forelimb and sternum of plotopterids differ significantly from those of penguins, so comparisons in terms of function may not be entirely accurate. Plotopterids are regarded as closely related to Anhingidae (darters) and Phalacrocoracidae (cormorants). On the other hand, there is a theory that this group may have a common ancestor with penguins due to the similarity of forelimb and brain morphology. However, the endocast morphology of stem group Sphenisciformes differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligocene
The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from Ancient Greek (''olígos'') 'few' and (''kainós'') 'new', and refers to the sparsity of Neontology, extant forms of Mollusca, molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major chang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coracoid
A coracoid is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is not homologous with the coracoid bone of most other vertebrates. In other tetrapods, it joins the scapula to the front end of the sternum and has a notch on the dorsal surface which, along with a similar notch on the ventral surface of the scapula, forms the socket in which the proximal end of the humerus (upper arm bone) is located. The acrocoracoid process is an expansion adjacent to this contact surface, to which the shoulderward end of the biceps brachii muscle attaches in these animals. In birds (and generally theropods and related animals), the entire unit is rigid and called scapulocoracoid. This plays a major role in bird flight. In other dinosaurs, the main bones of the pectoral girdle were the scapula (shoulder blade) an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yamaga Formation
The Yamaga Formation is a palaeontological formation located in Japan. It dates to the Upper Oligocene period. See also * List of fossil sites This list of fossil sites is a worldwide list of localities known well for the presence of fossils. Some entries in this list are notable for a single, unique find, while others are notable for the large number of fossils found there. Many of ... Further reading * (1993); ''Wildlife of Gondwana''. Reed. Geologic formations of Japan Paleogene System of Asia Paleogene Japan Oligocene Series Oligocene paleontological sites Paleontology in Japan {{Japan-geologic-formation-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supracoracoideus Muscle
Bird anatomy, or the physiology, physiological structure of birds' bodies, shows many unique adaptations, mostly aiding bird flight, 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 Digestion, digestive system. Skeletal system Birds have many bones that are hollow (skeletal pneumaticity, pneumatized) with criss-crossing struts or trusses for structural Strength of materials, strength. The number of hollow bones varies among species, though large Gliding flight, gliding and soaring birds tend to have the most. Respiratory air sacs often form air pockets within the semi-hollow bones of the bird's skeleton. The bones of diving birds are often less hollow than those of non-diving species. Penguins, loons, puffins, and kiwi (bird), kiwis are without pneumati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
