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Exapophyses
Exapophyses (singular: Exapophysis) are bony joints present in the cervicals (neck vertebrae) of some pterosaurs. Exapophyses lie on the centrum, the spool-shaped main body of each vertebra, where they are positioned adjacent to the main articulating surfaces between centra. Exapophyses which are next to the cotyle (concave front end of the centrum) are known as preexapophyses while those at the condyle (convex rear end) are called postexapophyses. Exapophyses act as accessory articulations, meaning that they complement the cotyle and condyle, as well as the zygapophyses (plate-like joints which lie on the neural arch above the centrum). The term was coined by Samuel Wendell Williston in 1897 during a description of ''Pteranodon'' (which he called "''Ornithostoma''" at the time). Exapophyses are a defining trait of the pterosaur subgroup Eupterodactyloidea Eupterodactyloidea (meaning "true Pterodactyloidea") is an extinct group of pterodactyloid pterosaurs that existed from the la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pterosaur
Pterosaurs (; from Greek ''pteron'' and ''sauros'', meaning "wing lizard") is 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 (228 to 66 million years ago). 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. There were two major types of pterosaurs. Basal pterosaurs (also called 'non-pterodactyloid pterosaurs' or 'rhamphorhynchoids') were smaller animals with fully toothed jaws and, typically, long tails. Their wide wing membranes probably included and connected the hind legs. On the ground, they would have had an awkward sprawling posture, but the anatomy of their joints and strong claws would have made them effective climbers, and some may have even lived in trees. Basal pterosaurs were insectiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic irregular bone whose complex structure is composed primarily of bone, and secondarily of hyaline cartilage. They show variation in the proportion contributed by these two tissue types; such variations correlate on one hand with the cerebral/caudal rank (i.e., location within the backbone), and on the other with phylogenetic differences among the vertebrate taxa. The basic configuration of a vertebra varies, but the bone is its ''body'', with the central part of the body constituting the ''centrum''. The upper (closer to) and lower (further from), respectively, the cranium and its central nervous system surfaces of the vertebra body support attachment to the intervertebral discs. The posterior part of a vertebra forms a vertebral arch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Articular Processes
The articular processes or zygapophyses (Greek ζυγον = "yoke" (because it links two vertebrae) + απο = "away" + φυσις = "process") of a vertebra are projections of the vertebra that serve the purpose of fitting with an adjacent vertebra. The actual region of contact is called the ''articular facet''.Moore, Keith L. et al. (2010) ''Clinically Oriented Anatomy'', 6th Ed, p.442 fig. 4.2 Articular processes spring from the junctions of the pedicles and laminæ, and there are two right and left, and two superior and inferior. These stick out of an end of a vertebra to lock with a zygapophysis on the next vertebra, to make the backbone more stable. * The superior processes or prezygapophysis project upward from a lower vertebra, and their articular surfaces are directed more or less backward (oblique coronal plane). * The inferior processes or postzygapophysis project downward from a higher vertebra, and their articular surfaces are directed more or less forward and outwa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samuel Wendell Williston
Samuel Wendell Williston (July 10, 1852 – August 30, 1918) was an American educator, entomologist, and paleontologist who was the first to propose that birds developed flight cursorially (by running), rather than arboreally (by leaping from tree to tree). He was a specialist on the flies, Diptera. He is remembered for Williston's law, which states that parts in an organism, such as arthropod limbs, become reduced in number and specialized in function through evolutionary history. Early life Williston was born in Boston, Massachusetts to Samuel Williston and Jane A. Williston née Turner. As a young child, Williston's family travelled to Kansas Territory in 1857 under the auspices of the New England Emigrant Aid Company to help fight the extension of slavery. He was raised in Manhattan, Kansas, attended public high school there, and graduated from Kansas State Agricultural College (now Kansas State University) in 1872, afterwards receiving a Master of Arts from that instituti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pteranodon
''Pteranodon'' (); from Ancient Greek (''pteron'', "wing") and (''anodon'', "toothless") is a genus of pterosaur that included some of the largest known flying reptiles, with ''P. longiceps'' having a wingspan of . They lived during the late Cretaceous geological period of North America in present-day Kansas, Nebraska, Wyoming, South Dakota and Alabama. More fossil specimens of ''Pteranodon'' have been found than any other pterosaur, with about 1,200 specimens known to science, many of them well preserved with nearly complete skulls and articulated skeletons. It was an important part of the animal community in the Western Interior Seaway. ''Pteranodon'' was not a dinosaur. By definition, all dinosaurs belong to the group Dinosauria; ''Pteranodon'' belongs to the group Pterosauria. Nonetheless, ''Pteranodon'' is the most famous pterosaur, frequently featured in dinosaur media and strongly associated with dinosaurs by the general public. While not dinosaurs, pterosaurs such as ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eupterodactyloidea
Eupterodactyloidea (meaning "true Pterodactyloidea") is an extinct group of pterodactyloid pterosaurs that existed from the latest Late Jurassic to the latest Late Cretaceous periods (Tithonian to Maastrichtian stages). Eupterodactyloids lived on all continents except Antarctica. Classification Eupterodactyloidea was named by S. Christopher Bennett in 1994 as an infraorder of the suborder Pterodactyloidea. Bennett defined it as an apomorphy-based clade. However, in 2010, Brian Andres re-defined the group as a stem-based taxon in his dissertation, and then formalized the definition in 2014 as all pterosaurs more closely related to ''Pteranodon longiceps'' than to ''Pterodactylus antiquus''. The slightly more exclusive group Ornithocheiroidea was re-defined in 2003 by Alexander Kellner. He defined it as the least inclusive clade containing ''Anhanguera blittersdorffi'', ''Pteranodon longiceps'', ''Dsungaripterus weii'', and ''Quetzalcoatlus northropi''. Ornithocheiroidea has often b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ctenochasmatidae
Ctenochasmatidae is a group of pterosaurs within the suborder Pterodactyloidea. They are characterized by their distinctive teeth, which are thought to have been used for filter-feeding. Ctenochasmatids lived from the Late Jurassic to the Early Cretaceous periods. The earliest known ctenochasmatid remains date to the Late Jurassic Kimmeridgian age. Previously, a fossil jaw recovered from the Middle Jurassic Stonesfield Slate formation in the United Kingdom, was considered the oldest known. This specimen supposedly represented a member of the family Ctenochasmatidae,Buffetaut, E. and Jeffrey, P. (2012). "A ctenochasmatid pterosaur from the Stonesfield Slate (Bathonian, Middle Jurassic) of Oxfordshire, England." ''Geological Magazine'', (advance online publication) though further examination suggested it actually belonged to a teleosaurid stem-crocodilian instead of a pterosaur. Classification Below is cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhamphorhynchidae
Rhamphorhynchidae is a group of early pterosaurs named after ''Rhamphorhynchus'', that lived in the Late Jurassic. The family Rhamphorhynchidae was named in 1870 by Harry Govier Seeley.Seeley, H.G. (1870). "The Orithosauria: An Elementary Study of the Bones of Pterodactyles." Cambridge, 135 p. Members of the group possess no more than 11 pairs of teeth in the rostrum, a deltopectoral crest that is constricted at the base but expanded at the distal end, and a bent phalange on the fifth toe. Rhamphorhynchidae traditionally contains two subfamilies: the Rhamphorhynchinae and the Scaphognathinae. While not recovered as distinct clades by all analyses, there do appear to be traits uniting members of each group. Rhamphorhynchines are more common, were lightly built, and had jaws ending in pointed tips that contained more teeth, which are often procumbent (pointed forward). Scaphognathines are comparatively quite rare, were more robust skeletally, and had shorter wing proportions. The b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homology (biology)
In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales and the forelegs of four-legged vertebrates like dogs and crocodiles are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, and it was explicitly analysed by Pierre Belon in 1555. In developmental biology, organs that developed in the embryo in the same manner and from similar origins, such as from matching p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
