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Hallopus
''Hallopus'' was a prehistoric reptile, named in 1877 as a species of ''Nanosaurus'' and classified by Othniel Charles Marsh, O. C. Marsh in 1881 from the Late Jurassic Morrison Formation. Today though the animal is thought to be a pseudosuchian more closely related to crocodilians. It was redescribed as a sphenosuchian Crocodylomorpha, crocodylomorph in 1970, now thought to be a paraphyletic group. It was a quite small animal, reaching a length of 1 m (3.3 ft) with long and slender limbs. ''Macelognathus'', a similarilly slender-proportioned crocodylomorph to ''Hallopus'', may be synonymous with it. History and naming The holotype specimen of ''Hallopus'' was discovered by near Canyon City, Colorado and acquired by a collector named Baldwin for three dollars in a local curiosity shop in Colorado Springs. According to letters later chronicled by Schuchert (1939), he found out about the fossil after hearing about the discovery of a supposed fossil bird, before later trav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hallopus Victor
''Hallopus'' was a prehistoric reptile, named in 1877 as a species of ''Nanosaurus'' and classified by Othniel Charles Marsh, O. C. Marsh in 1881 from the Late Jurassic Morrison Formation. Today though the animal is thought to be a pseudosuchian more closely related to crocodilians. It was redescribed as a sphenosuchian Crocodylomorpha, crocodylomorph in 1970, now thought to be a paraphyletic group. It was a quite small animal, reaching a length of 1 m (3.3 ft) with long and slender limbs. ''Macelognathus'', a similarilly slender-proportioned crocodylomorph to ''Hallopus'', may be synonymous with it. History and naming The holotype specimen of ''Hallopus'' was discovered by near Canyon City, Colorado and acquired by a collector named Baldwin for three dollars in a local curiosity shop in Colorado Springs. According to letters later chronicled by Schuchert (1939), he found out about the fossil after hearing about the discovery of a supposed fossil bird, before later trav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nanosaurus
''Nanosaurus'' ("small or dwarf lizard") is the name given to a genus of neornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic-age. Its fossils are known from the Morrison Formation of the south-western United States. The type and only species, ''Nanosaurus agilis'', was described and named by Othniel Charles Marsh in 1877. The taxon has a complicated taxonomic history, largely the work of Marsh and Peter M. Galton, involving the genera ''Laosaurus'', ''Hallopus'', ''Drinker'', ''Othnielia'', and ''Othnielosaurus'', the latter three now being considered to be synonyms of ''Nanosaurus''. It had historically been classified as a hypsilophodont or fabrosaur, types of generalized small bipedal herbivore, but more recent research has abandoned these groupings as paraphyletic and ''Nanosaurus'' is today considered a basal member of Neornithischia. Description ''Nanosaurus'' is known from material from all parts of the body, including tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macelognathus Vagans
''Macelognathus'' is an extinct genus of sphenosuchian crocodylomorph from the Late Jurassic. Originally it was believed be a turtle and later a dinosaur. It lived in what is now Wyoming, in North America.Moodie, R.L. 1908. The relationship of the turtles and plesiosaurs. Kansas University Scientific Bulletin, 4: 319–327. The type species, ''Macelognathus vagans'', was described by Othniel Charles Marsh in 1884 as a turtle based on a partial jaw from the Late Jurassic Morrison Formation at Como Bluff, Wyoming. After being referred to the Dinosauria by Moodie in 1908, it was later reclassified by Ostrom in 1971 as a crocodilian relative.Ostrom, J.H. (1971). "On the systematic position of ''Macelognathus vagans''". ''Postilla'' 153:1-10. Based on new material from the Morrison Formation at Fruita, Colorado, in 2005 Göhlich ''et al.'' identified it as a basal crocodylomorph ("sphenosuchian"). It is considered an example of convergent evolution, due to the similarities to caenag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macelognathus
''Macelognathus'' is an extinct genus of sphenosuchian crocodylomorph from the Late Jurassic. Originally it was believed be a turtle and later a dinosaur. It lived in what is now Wyoming, in North America.Moodie, R.L. 1908. The relationship of the turtles and plesiosaurs. Kansas University Scientific Bulletin, 4: 319–327. The type species, ''Macelognathus vagans'', was described by Othniel Charles Marsh in 1884 as a turtle based on a partial jaw from the Late Jurassic Morrison Formation at Como Bluff, Wyoming. After being referred to the Dinosauria by Moodie in 1908, it was later reclassified by Ostrom in 1971 as a crocodilian relative.Ostrom, J.H. (1971). "On the systematic position of ''Macelognathus vagans''". ''Postilla'' 153:1-10. Based on new material from the Morrison Formation at Fruita, Colorado, in 2005 Göhlich ''et al.'' identified it as a basal crocodylomorph ("sphenosuchian"). It is considered an example of convergent evolution, due to the similarities to cae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1881 In Paleontology
Molluscs Bivalves Dinosaurs Newly named dinosaurs Pterosaurs New taxa Synapsids Non-mammalian Paleontologists * Death of the Reverend William Fox a significant early collector of dinosaur fossils from the Isle of Wight.{{cite book, last = Farlow, first = James O., author2= M. K. Brett-Surmann, title = The Complete Dinosaur, publisher = Indiana University Press, year = 1999, location = Bloomington, Indiana, pages = 15, isbn = 0-253-21313-4 References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age. In the past, ''Malm'' was also used to indicate the unit of geological time, but this usage is now discouraged to make a clear distinction between lithostratigraphic and geochronologic/chronostratigraphic units. Subdivisions The Late Jurassic is divided into three ages, which correspond with the three (faunal) stages of Upper Jurassic rock: Paleogeography During the Late Jurassic Epoch, Pangaea broke up into two supercontinents, Laurasia to the north, and Gondwana to the south. The result of this break-up was the spawning of the Atlantic Ocean. However, at this time, the Atlantic Ocean was relatively narrow. Life forms of the epoch This epoch is well known for many famous types of dinosau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tridactyl
In biology, dactyly is the arrangement of digits (fingers and toes) on the hands, feet, or sometimes wings of a tetrapod animal. It comes from the Greek word δακτυλος (''dáktylos'') = "finger". Sometimes the ending "-dactylia" is used. The derived adjectives end with "-dactyl" or "-dactylous". As a normal feature Pentadactyly Pentadactyly (from Greek "five") is the condition of having five digits on each limb. It is traditionally believed that all living tetrapods are descended from an ancestor with a pentadactyl limb, although many species have now lost or transformed some or all of their digits by the process of evolution. However, this viewpoint was challenged by Stephen Jay Gould in his 1991 essay "Eight (Or Fewer) Little Piggies", where he pointed out polydactyly in early tetrapods and described the specializations of digit reduction. Despite the individual variations listed below, the relationship is to the original five-digit model. In reptiles, the limbs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coelurosauria
Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyrannosaurs, ornithomimosaurs, and maniraptorans; Maniraptora includes birds, the only known dinosaur group alive today. Most feathered dinosaurs discovered so far have been coelurosaurs. Philip J. Currie had considered it likely and probable that all coelurosaurs were feathered. However, several skin impressions found for some members of this group show pebbly, scaly skin, indicating that feathers did not completely replace scales in all taxa. In the past, Coelurosauria was used to refer to all small theropods, but this classification has since been abolished. Anatomy Bodyplan The studying of anatomical traits in coelurosaurs indicates that the last common ancestor had evolved the ability to eat and digest plant matter, adapting to an omniv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alick Walker
Alick Donald Walker (26 October 1925 – 4 December 1999) was a British palaeontologist, after whom the ''Alwalkeria'' genus of dinosaur is named. He was born in Skirpenbeck, near York and attended Pocklington School from 1936 to 1943. He began a degree course in engineering at Cambridge, but dropped out in 1944. In 1948 he returned to university after national service, reading Geology at the University of Bristol. On graduation, he join the research group of Professor Stanley Westoll at the University of Newcastle upon Tyne, working on the fossil reptiles of the Late Triassic found in Elgin. He was appointed Lecturer in Geology in 1954, while working on his PhD. The bony remains of the Elgin reptile fossils were poor, sometimes just indentations in rocks. Walker devised a new casting method to capture the anatomical information in these fossils, using PVC; many of the resulting casts are now in the National Museum of Scotland and the Natural History Museum. His early work was a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudosuchian
Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to 2011, the clade Pseudosuchia was often called Crurotarsi in reference to the crurotarsal ankle found in almost all members of the group, which traditionally included phytosaurs, ornithosuchids, and suchians. However, a major 2011 study of Triassic archosaur relations proposed that phytosaurs were not closely related to other traditional "crurotarsans", at least compared to "bird-line archosaurs" (Avemetatarsalians) such as pterosaurs and dinosaurs. As a result, the possession of a crurotarsal ankle was considered a plesiomorphic ("primitive") feature retained by pseudosuchians. Crurotarsi now refers to a broader group of reptiles including Pseudosuchia, Phytosauria, and Avemetatarsalia. Despite Pseudosuchia meaning "false crocodiles", the n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sacral Vertebrae
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It forms joints with four other bones. The two projections at the sides of the sacrum are called the alae (wings), and articulate with the ilium at the L-shaped sacroiliac joints. The upper part of the sacrum connects with the last lumbar vertebra (L5), and its lower part with the coccyx (tailbone) via the sacral and coccygeal cornua. The sacrum has three different surfaces which are shaped to accommodate surrounding pelvic structures. Overall it is concave (curved upon itself). The base of the sacrum, the broadest and uppermost part, is tilted forward as the sacral promontory internally. The central part is curved outward toward the posterior, allowing greater room for the pelv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pedeticosaurus
''Pedeticosaurus'' is an extinct genus of crocodylomorph from the Clarens Formation (Early Jurassic) of South Africa. The type species ''Pedeticosaurus leviseuri'' was named by Egbert Cornelis Nicolaas van Hoepen in 1915 on the basis of a mold of a mostly complete skeleton found in a quarry near Rosendal, Free State. The mold preserves most of the right half of the skeleton including the skull, ribs, dorsal vertebrae, forelimbs and hindlimbs, but not the tail. It is currently housed in the National Museum in Bloemfontein and cataloged as NMQR606. Taxonomy Van Hoepen originally established a new family for ''Pedeticosaurus'' called Pedeticosauridae, which he thought was closely related to the family Ornithosuchidae. In later years ''Pedeticosaurus'' was interpreted as either a member of Sphenosuchia or Protosuchia, both of which are groups of small-bodied Jurassic crocodylomorphs. Paleontologist A. D. Walker erected a new group called Pedeticosauria in 1968, which he named after ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
