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Mosasauria
Mosasauria is a clade of aquatic and semiaquatic squamates that lived during the Cretaceous period. Fossils belonging to the group have been found in all continents around the world. Early mosasaurians like dolichosaurs were small long-bodied lizards that inhabited nearshore coastal and freshwater environments; the Late Cretaceous saw the rise of large marine forms, the mosasaurids, which are the clade's best-known members. The clade is defined as all descendants of the last common ancestor of the mosasaur ''Mosasaurus hoffmannii'' and dolichosaurs ''Dolichosaurus'', ''Coniasaurus'', and '' Adriosaurus suessi''. Its placement within the squamate tree is highly controversial. Two prominent hypotheses include the varanoid hypothesis, which holds that mosasaurians are most closely related to monitor lizards, and the pythonomorph hypothesis, which argues for a sister relationship with snakes. A third ophidiomorph hypothesis argues that snakes are members of the Mosasauria as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mosasaur
Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Ancient Greek, Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. They belong to the order Squamata, which includes lizards and snakes. Mosasaurs probably evolved from an extinct group of aquatic lizards known as Aigialosauridae, aigialosaurs in the Late Cretaceous, Earliest Late Cretaceous with 42 described genera. During the last 20 million years of the Cretaceous period (Turonian–Maastrichtian ages), with the extinction of the ichthyosaurs and Pliosauridae, pliosaurs, mosasaurs became the dominant marine predators. They themselves became extinct as a result of the Cretaceous–Paleogene extinction event, K-Pg event at the end of the Cretaceous period, about 66 million years ago. Description Mosasaurs breathed air, were powerful swimmers, and were well-adapted to livi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Othniel Charles Marsh
Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among his legacies are the discovery or description of dozens of new species and theories on the origins of birds. Born into a modest family, Marsh was able to afford higher education thanks to the generosity of his wealthy uncle George Peabody. After graduating from Yale College in 1860 he travelled the world, studying anatomy, mineralogy and geology. He obtained a teaching position at Yale upon his return. From the 1870s to 1890s, he competed with rival paleontologist Edward Drinker Cope in a period of frenzied Western American expeditions known as the Bone Wars. Marsh's greatest legacy is the collection of Mesozoic reptiles, Cretaceous birds, and Mesozoic and Tertiary mammals that now constitute the backbone of the collections of Yale's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyosauria
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scleroglossa
Scleroglossa is a group of lizards that includes geckos, autarchoglossans (scincomorphs, anguimorphs, and varanoids), and amphisbaenians. Scleroglossa is supported by phylogenetic analyses that use morphological features (visible anatomical features). According to most morphological analyses, Scleroglossa is the sister group of the clade Iguania, which includes iguanas, chameleons, agamids, and New World lizards. Together, Scleroglossa and Iguania make up the crown group Squamata, the smallest evolutionary grouping to include all living lizards and snakes. The name Scleroglossa is derived from the Greek, ''skleros'', meaning "hard" and ''glossa'', meaning "tongue". The split between Scleroglossa and Iguania can be based on features of the tongue; iguanians have a muscular tongue and use lingual prehension to capture food, whereas scleroglossans have hard tongues and use teeth-and-jaw prehension to capture food, freeing the tongue for chemosensory activity. Recent phylogeneti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophidiomorpha
Ophidiomorpha is a clade composed of snakes and their primitive and early relatives proposed by Palci and Caldwell (2007)Palci, A., & Caldwell, M. W. (2007). Vestigial forelimbs and axial elongation in a 95 million-year-old non-snake squamate. Journal of Vertebrate Paleontology, 27(1), 1-7. The clade was defined as a node-based clade containing the most recent common ancestor of dolichosaurs, adriosaurs, '' Aphanizocnemus'', and fossil and extant Ophidia and all of its descendants. The existence of Ophidiomorpha as a clade may become problematic as it is placed within the Pythonomorpha, a clade that itself is not universally agreed upon containing mosasaurs and snakes, their most recent common ancestor and all of its descendants. Indeed, most 20th-century herpetologists and paleontologists rejected this idea and sought instead to demonstrate a close relationship between mosasaurs and varanid lizards. Pythonomorpha was later resurrected by a number of paleontologists (Lee, 1997; C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snake
Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more joints than their lizard ancestors, enabling them to swallow prey much larger than their heads ( cranial kinesis). To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most have only one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have evolved elongate bodies without limbs or with greatly reduced limbs about twenty-five times independently via convergent evolution, leading to many lineages of legless lizards. These resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, although this rule is not universal (see Amphisbae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sister Group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and taxon B are sister groups to each other. Taxa A and B, together with any other extant or extinct descendants of their most recent common ancestor (MRCA), form a monophyletic group, the clade AB. Clade AB and taxon C are also sister groups. Taxa A, B, and C, together with all other descendants of their MRCA form the clade ABC. The whole clade ABC is itself a subtree of a larger tree which offers yet more sister group relationships, both among the leaves and among larger, more deeply rooted clades. The tree structure shown connects through its root to the rest of the universal tree of life. In cladistic standards, taxa A, B, and C may represent specimens, species, genera, or any other taxonomic units. If A and B are at the same ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monitor Lizards
Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recognized. Monitor lizards have long necks, powerful tails and claws, and well-developed limbs. The adult length of extant species ranges from in some species, to over in the case of the Komodo dragon, though the extinct varanid known as megalania (''Varanus priscus'') may have been capable of reaching lengths more than . Most monitor species are terrestrial, but arboreal and semiaquatic monitors are also known. While most monitor lizards are carnivorous, eating eggs, smaller reptiles, fish, birds, insects, and small mammals, some also eat fruit and vegetation, depending on where they live. Distribution The various species cover a vast area, occurring through Africa, the Indian subcontinent, to China, the Ryukyu Islands in southern Japan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Varanoidea
Varanoidea is a superfamily of lizards, including the well-known family Varanidae (the monitors and goannas). Also included in the Varanoidea are the Lanthanotidae ( earless monitor lizards), and the extinct Palaeovaranidae. Throughout their long evolutionary history, varanoids have exhibited great diversity, both in habitat and form. This superfamily includes the largest-known terrestrial lizard, Megalania (5–6 meters), and the largest extant lizard, the Komodo dragon (''Varanus komodoensis'', 3+ meters). Evolution Either synonymous with, or a subgroup of, the group Platynota, the varanoids first appear in the fossil record in the latter part of Early Cretaceous, but possible varanoid ancestors have been traced back as far as Early Jurassic times. Among the earliest known varanoids are the monitor-like necrosaurids '' Palaeosaniwa canadensis'' from the Campanian (roughly 71-82 mya) of North America and '' Estesia mongoliensis'' and '' Telmasaurus grangeri'', both from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adriosaurus
''Adriosaurus'' is an extinct genus of squamate which lived in what is now Slovenia and other parts of Europe during the Late Cretaceous. It was snake-like and grew up to in length. This is the first fossil record of vestigial limbs in lizards. It lost its manus Manus may refer to: * Manus (anatomy), the zoological term for the distal portion of the forelimb of an animal (including the human hand) * ''Manus'' marriage, a type of marriage during Roman times Relating to locations around New Guinea * Man ... and forearm completely in order to elongate its axial skeleton. These unique anatomical features led to discussions of the evolutionary patterns of limb reduction in Squamata.Alessandro Palci and Michael W. Caldwell. 2007. Vestigial Forelimbs and Axial Elongation in a 95 Million-Year-Old Non-Snake Squamate. Journal of Vertebrate Paleontology Vol. 27, No. 1. pp. 1-7 ''Adriosaurus'' includes three species: ''A. microbrachis'' (“micro”, meaning small, and “brachis� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coniasaurus
''Coniasaurus'' is an extinct genus of Late Cretaceous marine Squamata, squamates that range in age from Cenomanian to Santonian. It was first described by Richard Owen in 1850 from lower Cenomanian Chalk Group, chalk deposits in southeast England (Sussex). Two species have been described from this genus: ''C. crassidens'' (Owen, 1850), known from Cenomanian to Santonian deposits from southeast England, Germany and North America, and ''C. gracilodens'' (Caldwell, 1999) from the Cenomanian of southeast England. ''Coniasaurus'' has only been described from incomplete specimens, but it is known to have had a relatively elongate skull with specialised teeth. By comparison with ''Dolichosaurus'', it may have had four short limbs and an elongate neck and body. A maximum length between has been proposed. Phylogenetics, Phylogenetic analysis suggests that ''Coniasaurus'' is a sister group to the Mosasauroidea within the clade Pythonomorpha. References {{Taxonbar, from=Q3686975 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dolichosaur
''Dolichosaurus'' (meaning "long lizard") is an extinct genus of marine squamate of the Upper Cretaceous Cenomanian chalk deposits of England. Sister-group relationships between coniasaurs, dolichosaurs, Aigialosauridae and Mosasauridae are an unresolved polytomy. The paleobiology of ''Dolichosaurus'' is reconstructed as similar to coniasaurs, nothosaurs, and modern sea snakes Sea snakes, or coral reef snakes, are elapid snakes that inhabit marine environments for most or all of their lives. They belong to two subfamilies, Hydrophiinae and Laticaudinae. Hydrophiinae also includes Australasian terrestrial snakes, whe ....Michael W. CaldwellOn the aquatic squamate ''Dolichosaurus longicollis'' Owen, 1850 (Cenomanian, Upper Cretaceous), and the evolution of elongate necks in squamates ''Journal of Vertebrate Paleontology'' 20(4):720-735. 2000. doi: https://dx.doi.org/10.1671/0272-4634(2000)020 720:OTASDL.0.CO;2 References Cretaceous lizards Late Cretaceous lepidos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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