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Ahdeskatanka
''Ahdeskatanka'' is an extinct genus of Alligatorinae, alligator from the Early Eocene Golden Valley Formation of North Dakota, USA. ''Ahdeskatanka'' had a short, rounded snout with globular teeth that are well-suited for crushing hard-shelled prey, though its exact ecology is not known. ''Ahdeskatanka'' inhabited the vast wetlands that covered much of western North Dakota during the Early Eocene Climatic Optimum, an environment it shared with at least three other crocodilians. These include the large caiman ''Chrysochampsa'' and at least two unnamed forms, one a large Crocodyloidea, crocodyloid and one more similar to ''Ahdeskatanka''. Phylogenetic analysis suggests that it was an early diverging member of the Alligatorinae, possibly related to ''Allognathosuchus'', though its position is not very stable. Only a single species, ''Ahdeskatanka russlanddeutsche'', is placed in this genus. History and naming ''Ahdeskatanka'' was named in 2024 by Adam Cossette and David Tarailo base ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ahdeskatanka Size
''Ahdeskatanka'' is an extinct genus of alligator from the Early Eocene Golden Valley Formation of North Dakota, USA. ''Ahdeskatanka'' had a short, rounded snout with globular teeth that are well-suited for crushing hard-shelled prey, though its exact ecology is not known. ''Ahdeskatanka'' inhabited the vast wetlands that covered much of western North Dakota during the Early Eocene Climatic Optimum, an environment it shared with at least three other crocodilians. These include the large caiman ''Chrysochampsa'' and at least two unnamed forms, one a large crocodyloid and one more similar to ''Ahdeskatanka''. Phylogenetic analysis suggests that it was an early diverging member of the Alligatorinae, possibly related to ''Allognathosuchus'', though its position is not very stable. Only a single species, ''Ahdeskatanka russlanddeutsche'', is placed in this genus. History and naming ''Ahdeskatanka'' was named in 2024 by Adam Cossette and David Tarailo based on a nearly complete skull r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrysochampsa
''Chrysochampsa'' is an extinct monospecific genus of Caimaninae, caiman of the clade Brachychampsini. Fossils have been found from the Golden Valley Formation of North Dakota and date back to the Wasatchian regional North American faunal stage of the early Eocene. During this time North Dakota experienced the Early Eocene Climatic Optimum, creating lush forests, swamps and meandering rivers that were the home to at least four distinct crocodilians. Unlike the contemporary ''Ahdeskatanka'', which was a small animal with crushing teeth, ''Chrysochampsa'' would have been a generalist. Due to its size and lack of significant mammalian carnivores, it would have been the apex predator of the region. The genus had been proposed to be Synonym (taxonomy), synonymous with ''Allognathosuchus'' in 2004, but this claim has since then been repeatedly refuted. A 2024 study has recovered it as an early branching member of the Caimaninae, forming a clade with Cretaceous forms such as ''Brachychamp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alligatorinae
Alligatorinae is a subfamily within the family Alligatoridae that contains the alligators and their closest extinct relatives, and is the sister taxon to Caimaninae (the caimans). Many genera in Alligatorinae are described, but only the genus ''Alligator'' is extant, with the remaining being extinct. Evolution Alligators and caimans split in North America during the early Tertiary or late Cretaceous (about 53 million to about 65 million years ago). The Chinese alligator split from the American alligator about 33 million years ago and likely descended from a lineage that crossed the Bering land bridge during the Neogene. The modern American alligator is well represented in the fossil record of the Pleistocene. The alligator's full mitochondrial genome was sequenced in the 1990s. The full genome, published in 2014, suggests that the alligator evolved much more slowly than mammals and birds. Phylogeny Alligatorinae is cladistically defined as ''Alligator missis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eocene
The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes from the Ancient Greek (''Ēṓs'', 'Eos, Dawn') and (''kainós'', "new") and refers to the "dawn" of modern ('new') fauna that appeared during the epoch.See: *Letter from William Whewell to Charles Lyell dated 31 January 1831 in: * From p. 55: "The period next antecedent we shall call Eocene, from ήως, aurora, and χαινος, recens, because the extremely small proportion of living species contained in these strata, indicates what may be considered the first commencement, or ''dawn'', of the existing state of the animate creation." The Eocene spans the time from the end of the Paleocene Epoch to the beginning of the Oligocene Epoch. The start of the Eocene is marked by a brief period in which the concentration of the carbon isoto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Russian Empire
The Russian Empire was an empire that spanned most of northern Eurasia from its establishment in November 1721 until the proclamation of the Russian Republic in September 1917. At its height in the late 19th century, it covered about , roughly one-sixth of the world's landmass, making it the list of largest empires, third-largest empire in history, behind only the British Empire, British and Mongol Empire, Mongol empires. It also Russian colonization of North America, colonized Alaska between 1799 and 1867. The empire's 1897 census, the only one it conducted, found a population of 125.6 million with considerable ethnic, linguistic, religious, and socioeconomic diversity. From the 10th to 17th centuries, the Russians had been ruled by a noble class known as the boyars, above whom was the tsar, an absolute monarch. The groundwork of the Russian Empire was laid by Ivan III (), who greatly expanded his domain, established a centralized Russian national state, and secured inde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skull Table
The skull roof or the roofing bones of the skull are a set of bones covering the brain, eyes and nostrils in bony fishes, including land-living vertebrates. The bones are derived from dermal bone and are part of the dermatocranium. In comparative anatomy, the term is applied to the whole dermatocranium. Romer, A.S. & T.S. Parsons. 1977. ''The Vertebrate Body.'' 5th ed. Saunders, Philadelphia. (6th ed. 1985) In general anatomy, the roofing bones may refer specifically to the bones that form above and alongside the brain and neurocranium (i.e., excluding the marginal upper jaw bones such as the maxilla and premaxilla). In human anatomy, the skull roof often refers specifically to the skullcap. Origin Early armoured fish (such as jawless ostracoderms and jawed placoderms) did not have a skull in the common understanding of the word, but instead had a cartilaginous endocranium that was partially open from above. The loose cartilage was topped by dermal bones forming armour. The d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prefrontal Bone
The prefrontal bone is a bone separating the lacrimal and frontal bones in many tetrapod skulls. It first evolved in the sarcopterygian clade Rhipidistia, which includes lungfish and the Tetrapodomorpha. The prefrontal is found in most modern and extinct lungfish, amphibians and reptiles. The prefrontal is lost in early mammaliaforms and so is not present in modern mammals either. In dinosaurs The prefrontal bone is a very small bone near the top of the skull, which is lost in many groups of coelurosaurian theropod dinosaurs and is completely absent in their modern descendants, the 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. Conversely, a well developed prefrontal is considered to be a primitive feature in dinosaurs. The prefrontal makes contact with several other ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allognathosuchus Wartheni
''Allognathosuchus'' (meaning "other jaw crocodile") is an extinct genus of alligatorine crocodylian with a complicated taxonomic history. It was named in 1921. Description ''Allognathosuchus'' was a medium-sized predator up to 1.5 m in length. This alligatorine is known for its stout jaws and bulbous teeth, found near the rear of the tooth row in upper and lower jaws. These adaptations have historically been interpreted as having been for crushing mollusks. Isolated bulbous teeth are often assigned to this genus, although such teeth are known from other crocodyliform lineages. Taxonomy The type species, ''A. polyodon'', is from the Eocene-age Bridger Formation of Wyoming; it is based on fossils that are difficult to distinguish from other Paleogene alligatorids. ''A. heterodon'' is from the Eocene-age Wasatch Formation of Wyoming, ''A. wartheni'' is from the Eocene-age Wildwood Formation (also known as the "Wildwood alligatorid" and possibly two species), and ''A. wouters ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jugal Bone
The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic bone, zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy The jugal bone is located on either side of the skull in the Ocular scales, circumorbital region. It is the origin of several masticatory muscles in the skull. The jugal and Lacrimal bone, lacrimal bones are the only two remaining from the ancestral circumorbital series: the prefrontal, postfrontal, postorbital, jugal, and lacrimal bones. During development, the jugal bone originates from dermal bone. In dinosaurs This bone is considered key in the determination of general traits in cases in which the entire skull has not been found intact (for instance, as with dinosaurs in paleontology). In some dinosaur genera the jugal also forms part of the lower margin of either the antorbital fenestra or the infratemporal fenestr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Bone
The lacrimal bones are two small and fragile bones of the facial skeleton; they are roughly the size of the little fingernail and situated at the front part of the medial wall of the orbit. They each have two surfaces and four borders. Several bony landmarks of the lacrimal bones function in the process of lacrimation. Specifically, the lacrimal bones help form the nasolacrimal canal necessary for tear translocation. A depression on the anterior inferior portion of one bone, the lacrimal fossa, houses the membranous lacrimal sac. Tears, from the lacrimal glands, collect in this sac during excessive lacrimation. The fluid then flows through the nasolacrimal duct and into the nasopharynx. This drainage results in what is commonly referred to a runny nose during excessive crying or tear production. Injury or fracture of the lacrimal bone can result in posttraumatic obstruction of the lacrimal pathways. Structure Lateral or orbital surface The lateral or orbital surface is divided b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maxillae
In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxillary bones are fused at the intermaxillary suture, forming the anterior nasal spine. This is similar to the mandible (lower jaw), which is also a fusion of two mandibular bones at the mandibular symphysis. The mandible is the movable part of the jaw. Anatomy Structure The maxilla is a paired bone - the two maxillae unite with each other at the intermaxillary suture. The maxilla consists of: * The body of the maxilla: pyramid-shaped; has an orbital, a nasal, an infratemporal, and a facial surface; contains the maxillary sinus. * Four processes: ** the zygomatic process ** the frontal process ** the alveolar process ** the palatine process It has three surfaces: * the anterior, posterior, medial Features of the maxilla include: * the infr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
