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Haemal Arch
A haemal arch also known as a chevron, is a bony arch on the ventral side of a tail vertebra of a vertebrate. The canal formed by the space between the arch and the vertebral body is the haemal canal. A spinous ventral process emerging from the haemal arch is referred to as the haemal spine. Blood vessels to and from the tail run through the arch. In reptiles, the caudofemoralis longus muscle, one of the main muscles involved in locomotion, attaches to the lateral sides of the haemal arches. In 1956, Alfred Sherwood Romer hypothesized that the position of the first haemal arch was sexually dimorphic in crocodilians and dinosaurs. However, subsequent research established that the size and position of the first haemal arch was not sexually dimorphic in crocodilians and found no evidence of significant variation in tyrannosaurid dinosaurs, indicating that haemal arches could not be used to distinguish between sexes after all. Haemal arches play an important role in the taxonomy of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nothronychus Chevrons
''Nothronychus'' (meaning "slothful claw") is a genus of therizinosaurid theropod dinosaurs that lived in North America during the Late Cretaceous period. The type species, ''Nothronychus mckinleyi'', was described by James Kirkland and Douglas G. Wolfe in 2001. It was recovered near New Mexico's border with Arizona, in an area known as the Zuni Basin, from rocks assigned to the Moreno Hill Formation, dating to the late Cretaceous period (mid-Turonian stage), around 91 million years ago. A second specimen, described in 2009 as a second species, ''Nothronychus graffami'', was found in the Tropic Shale of Utah, dating to the early Turonian, between one million and a half million years older than ''N. mckinleyi''. ''Nothronychus'' were bulky herbivorous theropods with wide, sloth-like hip (resembling that of the non-related ornithischians), four-toed feet with all four toes facing forward, elongated necks and prominent arms with sharp claws. Both species were similar in dimensions, ... [...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 ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * jawless fish, which include hagfish and lampreys * jawed vertebrates, which include: ** cartilaginous fish (sharks, rays, and ratfish) ** bony vertebrates, which include: *** ray-fins (the majority of living bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant vertebrates range in size from the frog species ''Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, which do not hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alfred Sherwood Romer
Alfred Sherwood Romer (December 28, 1894 – November 5, 1973) was an American paleontologist and biologist and a specialist in vertebrate evolution. Biography Alfred Romer was born in White Plains, New York, the son of Harry Houston Romer and his wife, Evalyn Sherwood. He was educated at White Plains High School. He studied at Amherst College for his Bachelor of Science Honours degree in biology, then at Columbia University for an M.Sc in Biology and a doctorate in zoology in 1921. Romer joined the department of geology and paleontology at the University of Chicago as an associate professor in 1923. He was an active researcher and teacher. His collecting program added important Paleozoic specimens to Chicago's Walker Museum of Paleontology. In 1934 he was appointed professor of biology at Harvard University. In 1946, he became director of the Harvard Museum of Comparative Zoology (MCZ). In 1954 Romer was awarded the Mary Clark Thompson Medal from the National Academy of Sc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sauropod
Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', ' lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their body), and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include ''Brachiosaurus'', ''Diplodocus'', ''Apatosaurus'' and ''Brontosaurus''. The oldest known unequivocal sauropod dinosaurs are known from the Early Jurassic. '' Isanosaurus'' and '' Antetonitrus'' were originally described as Triassic sauropods, but their age, and in the case of ''Antetonitrus'' also its sauropod status, were subsequently questioned. Sauropod-like sauropodomorph tracks from the Fleming Fjord Formation (Greenland) might, however, indicate the occurrence of the group in the Late Triassic. By the Late Jurassic (150 mill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaurs
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is the subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya; their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomic, morphological and ecological standpoints. Birds, at over 10,700 living species, are am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Othniel 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 Peabod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diplodocus
''Diplodocus'' (, , or ) was a genus of diplodocid sauropod dinosaurs, whose fossils were first discovered in 1877 by S. W. Williston. The generic name, coined by Othniel Charles Marsh in 1878, is a neo-Latin term derived from Greek διπλός (''diplos'') "double" and δοκός (''dokos'') "beam", in reference to the double-beamed chevron bones located in the underside of the tail, which were then considered unique. The genus of dinosaurs lived in what is now mid-western North America, at the end of the Jurassic period. It is one of the more common dinosaur fossils found in the middle to upper Morrison Formation, between about 154 and 152 million years ago, during the late Kimmeridgian Age. The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs, such as ''Apatosaurus'', ''Barosaurus'', '' Brachiosaurus'', '' Brontosaurus'', and '' Camarasaurus''. Its great size may have been a deterrent to the predators '' Allosaurus'' an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wintonotitan
''Wintonotitan'' (meaning " Winton titan") is a genus of titanosauriform dinosaur from late Albian (Early Cretaceous)-age Winton Formation of Australia. It is known from partial postcranial remains. Description and history Fossils that are now known under the name ''Wintonotitan'' were first found in 1974 by Keith Watts. At the time, the specimens were assigned to an '' Austrosaurus'' sp., ''Austrosaurus'' then being the only named Australian Cretaceous sauropod genus. These fossils, catalogued as QMF 7292, consisted of a left shoulder blade, much of the forelimbs, a number of back, hip, and tail vertebrae, part of the right hip, ribs, chevrons, and unidentifiable fragments. QMF 7292 was established as the type specimen of ''Wintonotitan'' in 2009 by Scott Hocknull and colleagues. Hocknull suggested that ''Austrosaurus mckillopi'' differed only slightly from the QMF 7292, the holotype of ''Wintonotitan wattsii'', and should be considered a ''nomen dubium''. The t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ichthyovenator
''Ichthyovenator'' is a genus of spinosaurid dinosaur that lived in what is now Laos, sometime between 125 and 113 million years ago, during the Aptian stage of the Early Cretaceous period. It is known from fossils collected from the Grès supérieurs Formation of the Savannakhet Basin, the first of which were found in 2010, consisting of a partial skeleton without the skull or limbs. This specimen became the holotype of the new genus and species ''Ichthyovenator laosensis'', and was described by palaeontologist Ronan Allain and colleagues in 2012. The generic name, meaning "fish hunter", refers to its assumed piscivorous lifestyle, while the specific name alludes to the country of Laos. In 2014, it was announced that more remains from the dig site had been recovered; these fossils included teeth, more vertebrae (backbones) and a pubic bone from the same individual. The holotype specimen is estimated to have been between long and to have weighed . ''Ichthyovenator''s te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edmontosaurus
''Edmontosaurus'' ( ) (meaning "lizard from Edmonton") is a genus of hadrosaurid (duck-billed) dinosaur. It contains two known species: ''Edmontosaurus regalis'' and '' Edmontosaurus annectens''. Fossils of ''E. regalis'' have been found in rocks of western North America that date from the late Campanian stage of the Cretaceous Period 73 million years ago, while those of ''E. annectens'' were found in the same geographic region but in rocks dated to the end of the Maastrichtian stage of the Cretaceous, 66 million years ago. ''Edmontosaurus'' was one of the last non-avian dinosaurs, and lived alongside dinosaurs like ''Triceratops'', ''Tyrannosaurus'', ''Ankylosaurus'', and '' Pachycephalosaurus'' shortly before the Cretaceous–Paleogene extinction event. ''Edmontosaurus'' included some of the largest hadrosaurid species, with ''E. annectens'' measuring up to in length and weighing around in average asymptotic body mass, although some individuals would have been larger ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oksoko (dinosaur)
''Oksoko'' (''Oak-soak-oh''; from '' Öksökö'', a mythical bird of Yakut folklore) is a genus of oviraptorid dinosaur from the Late Cretaceous of Asia, that lived in what is now the Nemegt Formation in Mongolia. It includes the type species ''Oksoko avarsan''. History of discovery The first specimen of ''Oksoko'', MPC-D 100/33, was discovered in 1974 by the Soviet-Mongolian Palaeontological Expedition at the Bügiin Tsav locality in the Nemegt Formation of Mongolia. It is represented by a partial subadult postcranial skeleton. The holotype specimen is a block of an assemblage of three individuals buried in life positions that has been labelled as MPC-D 102/110. The first individual, subcatalogued as MPC-D 102/110a, is a partial skeleton of a juvenile preserving the skull, cervical vertebrae, pelvis, hindlimbs, and caudal vertebrae. Another specimen in this block is represented by MPC-D 102/110b, a large quadrate and quadratojugal. The third specimen in this assembla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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