Proximodorsal process

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The proximodorsal process is a feature of the skeleton of archosaurs. It may be a pair of tabs or blade - shaped flanges on the pelvis, and serves as an anchor point for the attachment of leg muscles. This process is of particular importance in the anatomy and comparative morphology of Mesozoic birds and advanced maniraptoran dinosaurs. The pelvis is made up of three paired bones and a sacrum. The three paired bones are called the ilium, the ischium, and the pubis. On the ischium there may be an obturator process and/or a proximodorsal process. The more primitive condition is for there to be no proximodorsal process, but a large obturator process. In primitive birds the ischia are complex, usually with a small or even absent obturator process and a large, rectangular, proximodorsal process extending up toward the ilium. This is the condition in Archaeopteryx , Confuciusornis, and enantiornithines. [1] The South American dromaeosaurs called the unenlagiinae have an intermediate condition [2] between the two, with both a large obturator process and a proximodorsal process. [3]

Process (anatomy) projection or outgrowth of tissue from a larger body

In anatomy, a process is a projection or outgrowth of tissue from a larger body. For instance, in a vertebra, a process may serve for muscle attachment and leverage, or to fit, with another vertebra. The word is used even at the microanatomic level, where cells can have processes such as cilia or pedicels. Depending on the tissue, processes may also be called by other terms, such as apophysis, tubercle, or protuberance.

Archosaur group of reptiles

Archosaurs are a group of diapsid amniotes whose living representatives consist of birds and crocodilians. This group also includes all extinct dinosaurs, extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most recent common ancestor of living birds and crocodilians and all of its descendants. It includes two main clades: Pseudosuchia, which includes crocodilians and their extinct relatives, and Avemetatarsalia, which includes birds and their extinct relatives.

Anatomy The study of the structure of organisms and their parts

Anatomy is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science which deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, and phylogeny, as these are the processes by which anatomy is generated over immediate (embryology) and long (evolution) timescales. Anatomy and physiology, which study (respectively) the structure and function of organisms and their parts, make a natural pair of related disciplines, and they are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine.

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Dinosaur Superorder of reptiles (fossil)

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, 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 million years ago; their dominance continued through the Jurassic and Cretaceous periods. Reverse genetic engineering and the fossil record both demonstrate that birds are modern feathered dinosaurs, having evolved from earlier theropods during the late Jurassic Period. As such, birds were the only dinosaur lineage to survive the Cretaceous–Paleogene extinction event 66 million years ago. Dinosaurs can therefore be divided into avian dinosaurs, or birds; and non-avian dinosaurs, which are all dinosaurs other than birds. This article deals primarily with non-avian dinosaurs.

Ornithischia order of reptiles (fossil)

Ornithischia is an extinct clade of mainly herbivorous dinosaurs characterized by a pelvic structure similar to that of birds. The name Ornithischia, or "bird-hipped", reflects this similarity and is derived from the Greek stem ornith- (ὀρνιθ-), meaning "of a bird", and ischion (ἴσχιον), plural ischia, meaning "hip joint". However, birds are only distantly related to this group as birds are theropod dinosaurs.

<i>Protoavis</i> genus of dinosaurs

Protoavis is a problematic dinosaurian taxon known from fragmentary remains from Late Triassic Norian stage deposits near Post, Texas. Much controversy remains over the animal, and there are many different interpretations of what Protoavis actually is. When it was first described, the fossils were described as being from a primitive bird which, if the identification is valid, would push back avian origins some 60-75 million years.

Oviraptorosauria infraorder of reptiles (fossil)

Oviraptorosaurs are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America, though they have also been reported from the Eumeralla Formation of Australia and Lecho Formation in South America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or without bony crests atop the head. They ranged in size from Caudipteryx, which was the size of a turkey, to the 8-metre-long, 1.4-ton Gigantoraptor. The group is close to the ancestry of birds. Analyses like those of Maryanska et al (2002) and Osmólska et al. (2004) suggest that they may represent primitive flightless birds. The most complete oviraptorosaur specimens have been found in Asia. The North American oviraptorosaur record is sparse.

<i>Avimimus</i> genus of reptiles (fossil)

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Achillobator is a dromaeosaurid theropod dinosaur that lived roughly 93 to 80 million years ago during the Late Cretaceous in what is now Mongolia, in Asia. It was among the largest dromaeosaurs; the holotype and only known individual of Achillobator is estimated at 5 to 6 m long. Achillobator was a moderately-built, ground-dwelling, bipedal carnivore. It would have been an active predator, hunting with the enlarged, sickle-shaped claw on the second toe.

<i>Rahonavis</i> genus of reptiles (fossil)

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<i>Mononykus</i> genus of reptiles (fossil)

Mononykus was a theropod dinosaur from late Cretaceous Mongolia with long, skinny legs. It moved about on two legs, was likely very nimble and could run at high speeds, something that would have been useful in the open flood plains where it lived. It had a small skull, and its teeth were small and pointed, suggesting that it ate insects and small animals, such as lizards and mammals. Its large eyes might have allowed Mononykus to hunt by night, when it was cooler and there would have been fewer predators about. Mononykus was originally named Mononychus in 1993, but later that year, it was renamed because the original name had already been used for a beetle named by Johann Schueppel, a German entomologist.

Ischium lower and back part of the hip bone

The ischium forms the lower and back part of the hip bone.

Pubis (bone) the ventral and anterior of the three principal bones composing either half of the pelvis

In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.

<i>Marasuchus</i> Marasuchus was a small, two-legged reptile that was a close relative of dinosaurs.

Marasuchus is a genus of basal dinosauriform archosaur which lived during the late Triassic in what is now La Rioja Province, Argentina. It possessed some, but not all of the adaptations which traditionally characterized dinosaurs. For example, its proportions indicate that it was likely bipedal as in early dinosaurs, and it shared certain specific characteristics with that group such, most relating to the hip and the head of the femur. Nevertheless, it lacked certain dinosaur-like features such as a perforated acetabulum, and it had several plesiomorphic ("primitive") features of the ankle.

<i>Sinornis</i> species of bird (fossil)

Sinornis is a genus of enantiornithean birds from the Lower Cretaceous Jiufotang Formation of the People's Republic of China.

The obturator process is an anatomical feature on the pelvis of archosaurs.

Andrzej Elżanowski is a Polish paleontologist and vertebrate zoologist specializing in bird phylogeny. Together with Peter Wellnhofer he described a coelurosaur theropod Archaeornithoides in 1992. He works also on Mesozoic birds, especially Archaeopterygiformes – he is author of the chapter "Archaeopterygidae" in book edited by Luis Chiappe and Lawrence Witmer entitled Mesozoic Birds: Above the Heads of Dinosaurs. In 2001 he determined that Solnhofen specimen of Archaeopteryx represents new species and genus and coined new specific name – Wellnhoferia grandis – for it. He works now in the Faculty of „Artes Liberales” at the University of Warsaw.

Hip bone bone of the pelvis

The hip bone is a large irregular bone, constricted in the center and expanded above and below. In some vertebrates it is composed of three parts: the ilium, ischium, and the pubis.

Poposauroidea superfamily of reptiles

Poposauroidea is a clade of advanced pseudosuchians. It includes poposaurids, shuvosaurids, ctenosauriscids, and other unusual pseudosuchians such as Qianosuchus and Lotosaurus. However, it excludes most large predatory quadrupedal "rauisuchians" such as rauisuchids and "prestosuchids". Those reptiles are now allied with crocodylomorphs in a clade known as Loricata, which is the sister taxon to the poposauroids in the clade Paracrocodylomorpha. Although it was first formally defined in 2007, the name "Poposauroidea" has been used for many years. The group has been referred to as Poposauridae by some authors, although this name is often used more narrowly to refer to the family that includes Poposaurus and its close relatives.

This glossary explains technical terms commonly employed in the description of dinosaur body fossils. Besides dinosaur-specific terms, it covers terms with wider usage, when these are of central importance in the study of dinosaurs or when their discussion in the context of dinosaurs is beneficial. The glossary does not cover ichnological and bone histological terms, nor does it cover measurements.

<i>Dracoraptor</i> genus of reptiles (fossil)

Dracoraptor is a genus of carnivorous neotheropod dinosaur from the Hettangian age of the Early Jurassic period of Wales.

<i>Jianianhualong</i> genus of reptiles

Jianianhualong is a genus of troodontid theropod dinosaur from the Early Cretaceous of China. It contains a single species, Jianianhualong tengi, named in 2017 by Xu Xing and colleagues based on an articulated skeleton preserving feathers. The feathers at the middle of the tail of Jianianhualong are asymmetric, being the first record of asymmetrical feathers among the troodontids. Despite aerodynamic differences from the flight feathers of modern birds, the feathers in the tail vane of Jianianhualong could have functioned in drag reduction whilst the animal was moving. The discovery of Jianianhualong supports the notion that asymmetrical feathers appeared early in the evolutionary history of the Paraves.

<i>Caihong</i> genus of dinosaurs

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References

  1. Witmer, Lawrence M. (2002) "The Debate on Avian Ancestry: Phylogeny, Function, and Fossils." pp. 3-30 in "Mesozoic Birds: above the heads of dinosaurs" Chiappe, L.M., and Witmer, L.M. (eds.) University of California Press, Berkeley.
  2. Forster, Catherine, Sampson, Scott D., Chiappe, Luis M., Krause, David W. (1998) "The Theropod Ancestry of Birds:New Evidence from the Late Cretaceous of Madagascar" "Nature" 279:1915-1919. 20 march 1998
  3. Makovicky, Peter J., Apestguia, Sebastian, Agnolin, Frederico L. (2005) "The earliest dromaeosaurid theropod from South America" "Nature" 437:1007-1011 13 October 2005.