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Merriamosauria
Merriamosauria is an extinct clade of ichthyosaurs. It was named by Ryosuke Motani in his 1999 analysis of the relationships of ichthyopterygian marine reptiles and was defined in phylogenetic terms as a stem-based taxon including "the last common ancestor of ''Shastasaurus pacificus'' and '' Ichthyosaurus communis'', and all of its descendants." The name honours John Campbell Merriam. Based on this definition, Merriamosauria includes most ichthyosaurs except for several Triassic groups such as the clade Mixosauria, the family Cymbospondylidae, and perhaps the family Toretocnemidae. Merriamosaurs are characterized by features in their pectoral girdles and limb bones, including an extensive connection between the scapula and the coracoid bone, the absence of the first metacarpal and the absence of a pisiform bone. In addition to ''Shastasaurus,'' this clade includes ''Shonisaurus, Guizhouichthyosaurus,'' an unnamed Norian The Norian is a division of the Triassic Period. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyosaur
Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, although the term is now used more for the parent clade of the Ichthyosauria). Ichthyosaurs thrived during much of the Mesozoic era; based on fossil evidence, they first appeared around 250 million years ago ( Ma) and at least one species survived until about 90 million years ago, into the Late Cretaceous. During the Early Triassic epoch, ichthyosaurs and other ichthyosauromorphs evolved from a group of unidentified land reptiles that returned to the sea, in a development similar to how the mammalian land-dwelling ancestors of modern-day dolphins and whales returned to the sea millions of years later, which they gradually came to resemble in a case of convergent evolution. Ichthyosaurs were particularly abundant in the Late Triassic a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Besanosauridae
''Besanosaurus'' (meaning "Besano ombardy, N. Italy">Italy.html" ;"title="ombardy, N. Italy">ombardy, N. Italylizard") is a genus of large ichthyosaur (a marine reptile, not a dinosaur) that lived during the middle Triassic period, approximately 235 million years ago. This marine reptile came from its own family Besanosauridae and was named by Dal Sasso and Pinna in 1996. The type of species is ''Besanosaurus leptorhynchus'' meaning "long-beaked reptile from Besano." Discovery The bones of ''Besanosaurus'' were first discovered in "Sasso Caldo" quarry in the spring of 1993 by the volunteers of the paleontological group of Besano, a small town in the Lombardy region of north Italy. The fossil was almost completely embedded in the rock and could be first seen only through x-rays; to detect the content of the 38 slabs of stone enclosing the skeleton, 145 radiographs were necessary. The skeleton of ''Besanosaurus'' came to light in the paleontological laboratory of Museo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Californosauridae
''Californosaurus'' ('California lizard') is an extinct genus of ichthyosaur, an extinct marine reptile, from the Lower Hosselkus Limestone (Carnian, Late Triassic) of California. Taxonomy Merriam (1902) described it as a new species of ''Shastasaurus'', ''S. perrini''. He later recognized the species as generically distinct from the ''Shastasaurus'' type species, erecting '' Delphinosaurus'' for ''S. perrini''. However, ''Delphinosaurus'' had been previously used for an ophthalmosaurid from Albian-Cenomanian deposits in European Russia, and Kuhn (1934) provided the generic replacement name ''Californosaurus''. Merriam (1938) independently erected ''Perrinosaurus'' to replace ''Delphinosaurus'', but this is a junior objective synonym. Description The long-snouted head is small in comparison with the rest of the body, as in basal ichthyosaurs such as ''Mixosaurus'' and ''Cymbospondylus ''Cymbospondylus'' (a Greek word meaning "boat vertebrae") was a basal early ichthyosa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and Ma (million years ago). It is preceded by the Early Triassic Epoch and followed by the Late Triassic Epoch. The Middle Triassic is divided into the Anisian and Ladinian ages or stages. Formerly the middle series in the Triassic was also known as Muschelkalk. This name is now only used for a specific unit of rock strata with approximately Middle Triassic age, found in western Europe. Middle Triassic fauna Following the Permian–Triassic extinction event, the most devastating of all mass-extinctions, life recovered slowly. In the Middle Triassic, many groups of organisms reached higher diversity again, such as the marine reptiles (e.g. ichthyosaurs, sauropterygians, thallatosaurs), ray-finned fish and many invertebrate groups like ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cymbospondylidae
Cymbospondylidae is an extinct family of Hueneosaurian Ichthyosaurs known from the Middle Triassic of Europe, North America, and Asia. Taxonomy Cymbospondylidae is a basal clade of ichthyosaurs. In 2000, Maischand and Matzke recovered cymbospondylids as members of Hueneosauria and more derived than mixosaurids, but Ji and colleagues found cymbospondylids to be outside of Hueneosauria in 2015. These two studies defined the group in two different ways, with the former defining it as the least inclusive clade containing both '' Cymbospondylus petrinus'' and '' Phantomosaurus neubigi'', whereas the latter defined it as the least inclusive clade containing both ''Cymbospondylus piscosus'' and ''Xinminosaurus catactes ''Xinminosaurus'' is an extinct genus of cymbospondylid ichthyosaur known from the Middle Triassic (mid-late Anisian stage) of Guizhou Province, China. Etymology The generic name is derived from ''Xinmin'', the district where the fossil was ...''. References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Last Common Ancestor
In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The term is also used in reference to the ancestry of groups of genes (haplotypes) rather than organisms. The MRCA of a set of individuals can sometimes be determined by referring to an established pedigree. However, in general, it is impossible to identify the exact MRCA of a large set of individuals, but an estimate of the time at which the MRCA lived can often be given. Such ''time to most recent common ancestor'' (''TMRCA'') estimates can be given based on DNA test results and established mutation rates as practiced in genetic genealogy, or by reference to a non-genetic, mathematical model or computer simulation. In organisms using sexual reproduction, the ''matrilineal MRCA'' and ''patrilineal MRCA'' are the MRCAs of a given population c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyosaurus Communis
''Ichthyosaurus'' (derived from Greek ' () meaning 'fish' and ' () meaning 'lizard') is a genus of ichthyosaurs from the Early Jurassic (Hettangian - Pliensbachian), with possible Late Triassic record, from Europe (Belgium, England, Germany, Switzerland, and Portugal). It is among the best known ichthyosaur genera, as it is the type genus of the order Ichthyosauria.Maisch MW, Matzke AT. 2000. The Ichthyosauria. ''Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie)'' 298: 1-159McGowan C, Motani R. 2003. Ichthyopterygia. – In: Sues, H.-D. (ed.): ''Handbook of Paleoherpetology, Part 8, Verlag Dr. Friedrich Pfeil'', 175 pp., 101 figs., 19 plts; MünchenMaisch MW, Reisdorf AG, Schlatter R, Wetzel A. 2008. A large skull of Ichthyosaurus (Reptilia: Ichthyosauria) from the Lower Sinemurian (Lower Jurassic) of Frick (NW Switzerland). ''Swiss Journal of Geosciences'' 101: 617-627. History of discovery ''Ichthyosaurus'' was the first complete fossil to be discovere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Campbell Merriam
John Campbell Merriam (October 20, 1869 – October 30, 1945) was an American paleontologist, educator, and conservationist. The first vertebrate paleontologist on the West Coast of the United States, he is best known for his taxonomy of vertebrate fossils at the La Brea Tar Pits in Los Angeles, particularly with the genus ''Smilodon'', more commonly known as the sabertooth cat. He is also known for his work to extend the reach of the National Park Service. Biography He was born in Hopkinton, Iowa, the eldest child of postmaster, store proprietor, and American Civil War veteran Charles E. Merriam. His middle name Campbell was his mother's middle name, and the maiden name of his maternal grandmother. Both his father Charles E. Merriam and his paternal uncle Henry C. Merriam had served as officers in the 12th Iowa Infantry, Company K; after capture at the Battle of Shiloh, they were sent to Libby Prison for some time before being returned to the battlefields. Eventually, whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mixosauria
The Mixosauria were an early group of ichthyosaurs, living between 247.2 and 235 million years ago, during the Triassic period. Fossils of mixosaurs have been found all over the world: China, Timor, Indonesia, Italy, Germany, Spitsbergen, Switzerland, Svalbard, Canada, Alaska, and Nevada. Cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ... based on Motani (1999), Maisch and Matzke (2000), and Jiang, Schmitz, Hao & Sun (2006), with clade and generic names following Maisch (2010): References Triassic ichthyosaurs Triassic reptiles of Asia Triassic reptiles of Europe Triassic reptiles of North America Fossil taxa described in 1999 {{ichthyosaur-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pectoral Girdle
The shoulder girdle or pectoral girdle is the set of bones in the appendicular skeleton which connects to the arm on each side. In humans it consists of the clavicle and scapula; in those species with three bones in the shoulder, it consists of the clavicle, scapula, and coracoid. Some mammalian species (such as the dog and the horse) have only the scapula. The pectoral girdles are to the upper limbs as the pelvic girdle is to the lower limbs; the girdles are the parts of the appendicular skeleton that anchor the appendages to the axial skeleton. In humans, the only true anatomical joints between the shoulder girdle and the axial skeleton are the sternoclavicular joints on each side. No anatomical joint exists between each scapula and the rib cage; instead the muscular connection or physiological joint between the two permits great mobility of the shoulder girdle compared to the compact pelvic girdle; because the upper limb is not usually involved in weight bearing, its stabilit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toretocnemidae
The Toretocnemidae were a group of ichthyosaurs that lived in the Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ... period. References *Maisch, M.W. and Matzke, A.T., 2000, "The Ichthyosauria", ''Stuttgarter Beiträge zur Naturkunde Series B (Geologie und Paläontologie)'', 298: 1-159 Late Triassic ichthyosaurs Prehistoric reptile families {{triassic-reptile-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by Computational phylogenetics, phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a phylogenetic tree can be living taxa or fossils, and represent the "end" or the present time in an evolutionary lineage. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the tree. An unrooted tree diagram (a network) makes no assumption about the ancestral line, and does ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
