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Protoavis
''Protoavis'' (meaning "first bird") is a problematic 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. The original describer of ''Protoavis texensis'', Sankar Chatterjee of Texas Tech University, interpreted the type specimen to have come from a single animal, specifically a 35 cm tall bird that lived in what is now Texas, USA, around 210 million years ago. Though it existed far earlier than ''Archaeopteryx'', its skeletal structure is more bird-like. ''Protoavis'' has been reconstructed as a carnivorous bird that had teeth on the tip of its jaws and eyes located at the front of the skull, suggesting a nocturnal or crepuscular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sankar Chatterjee
Sankar Chatterjee (born May 28, 1943) is a paleontologist, and is the Paul W. Horn Professor of Geosciences at Texas Tech University and Curator of Paleontology at the Museum of Texas Tech University. He earned his Ph. D. from the University of Calcutta in 1970 and was a Post-doctoral Fellow at the Smithsonian Institution from 1977-1978. Chatterjee has focused on the origin, evolution, functional anatomy, and systematics of Mesozoic vertebrates, including basal archosaurs, dinosaurs, pterosaurs, and birds. He has researched Late Triassic reptiles in India, such as phytosaurs, rhynchosaurs, and prolacertiformes. He is best known for his work on vertebrates recovered in the 1980s from the Post Quarry in the Late Triassic Cooper Canyon Formation (Dockum Group) of West Texas. The material includes the large rauisuchian '' Postosuchus'', which was named for the nearby town of Post. It also included controversial specimens Chatterjee identified as being avian ('' Protoavis''). The i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bull Canyon Formation
The Cooper Canyon Formation is a geological formation of Norian age in Texas and New Mexico.Weishampel, David B; et al. (2004).Dinosaur distribution (Late Triassic, North America)" In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 518–521. . Type area of the formation is situated in Garza County, Texas. An equivalent formation in eastern New Mexico is named Bull Canyon Formation. Some researchers argue that the latter name should be abandoned. The formation consist of reddish siltstone and mudstone with lenses of sandstone and conglomerate. Thickness of the formation in the type area is 161.5 meters. It increases to the south, and in some places exceeds 200 m. The formation contains diverse fossils, including vertebrate remains. Vertebrate fauna Temnospondyls Allokotosaurs Archosaurs and related Procolophonomorphs Misc. See also * List of dinosaur-bearing rock formatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Triassic
The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. The corresponding series of rock beds is known as the Upper Triassic. The Late Triassic is divided into the Carnian, Norian and Rhaetian Ages. Many of the first dinosaurs evolved during the Late Triassic, including ''Plateosaurus'', ''Coelophysis'', and '' Eoraptor''. The Triassic–Jurassic extinction event began during this epoch and is one of the five major mass extinction events of the Earth. Etymology The Triassic was named in 1834 by Friedrich von Alberti, after a succession of three distinct rock layers (Greek meaning 'triad') that are widespread in southern Germany: the lower Buntsandstein (colourful sandstone'')'', the middle Muschelkalk (shell-bearing limestone) and the upper Keuper (coloured clay). The Late Triassic Ser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lawrence Witmer
Lawrence M. Witmer (born October 10, 1959, at Rochester, New York) is an American paleontologist and paleobiologist. He is a Professor of Anatomy and a Chang Ying-Chien Professor of Paleontology at the Department of Biomedical Sciences at the Heritage College of Osteopathic Medicine in Ohio University. Witmer is considered to be one of the world's foremost experts on soft-tissue anatomy of the skull in extinct animals such as dinosaurs and pterosaurs. One of Witmer's largest contributions to vertebrate paleontology was the creation of the Extant Phylogenetic Bracket approach to ancestral character state reconstruction.Witmer, L.M. 1995.The Extant Phylogenetic Bracket and the Importance of Reconstructing Soft Tissues in Fossils. in Thomason, J.J. (ed). Functional Morphology in Vertebrate Paleontology. New York. Cambridge University Press. pp: 19–33. This methodology incorporates extensive comparative anatomy using physical and digital dissections of extant (not extinct) animals. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megalancosaurus
''Megalancosaurus'' is a genus of extinct reptile from the Late Triassic Dolomia di Forni Formation and Zorzino Limestone of northern Italy, and one of the best known drepanosaurids. The type species is ''M. preonensis''; a translation of the animal's scientific name would be "long armed reptile from the Preone Valley." Anatomy ''Megalancosaurus'' was fairly small, its adult length was only about 25 centimeters (10 inches). It was built like a chameleon and probably lived a similar arboreal lifestyle, feeding on insects and other small animals. Even its feet were chameleon like, with two toes being opposed to the remaining three. The tail is long, prehensile, and bears a strange claw-like organ made of fused vertebrae at its end. Its shoulders formed a withers that would have served as an attachment site for especially strong muscles. Some specimens have an opposable digit on the feet. Because not all members of the species appear to bear this digit, it has been speculate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cervical Vertebra
In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have seven cervical vertebrae, with the only three known exceptions being the manatee with six, the two-toed sloth with five or six, and the three-toed sloth with nine. In humans, cervical vertebrae are the smallest of the true vertebrae and can be readily distinguished from those of the thoracic or lumbar regions by the presence of a foramen (hole) in each transverse process, through which the vertebral artery, vertebral veins, and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parietal Bone
The parietal bones () are two bones in the skull which, when joined at a fibrous joint, form the sides and roof of the cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, and four angles. It is named from the Latin ''paries'' (''-ietis''), wall. Surfaces External The external surface ig. 1is convex, smooth, and marked near the center by an eminence, the parietal eminence (''tuber parietale''), which indicates the point where ossification commenced. Crossing the middle of the bone in an arched direction are two curved lines, the superior and inferior temporal lines; the former gives attachment to the temporal fascia, and the latter indicates the upper limit of the muscular origin of the temporal muscle. Above these lines the bone is covered by a tough layer of fibrous tissue – the epicranial aponeurosis; below them it forms part of the temporal fossa, and affords attachment to the temporal muscle. At the back part and close t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troodon
''Troodon'' ( ; ''Troödon'' in older sources) is a wastebasket taxon and a dubious genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Late Cretaceous period (about 77 mya). It includes at least one species, ''Troodon formosus'', known from Montana. Discovered in October 1855, ''T. formosus'' was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877. Several well-known troodontid specimens from the Dinosaur Park Formation in Alberta were once believed to be members of this genus. However, recent analyses in 2017 have found the genus to be undiagnostic and referred some of these specimens to the genus '' Stenonychosaurus'' (long believed to be synonymous with ''Troodon'') and others to the genus '' Latenivenatrix''. The genus name is Ancient Greek for "wounding tooth", referring to the teeth, which were different from those of most other theropods known at the time of their discovery. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endocast
An endocast is the internal cast of a hollow object, often referring to the cranial vault in the study of brain development in humans and other organisms. Endocasts can be artificially made for examining the properties of a hollow, inaccessible space, or they may occur naturally through fossilization. Cranial endocasts Artificial casts Endocasts of the inside of the neurocranium (braincase) are often made in paleoanthropology to study brain structures and hemispheric specialization in extinct human ancestors. While an endocast can not directly reveal brain structure, it can allow scientists to gauge the size of areas of the brain situated close to the surface, notably Wernicke's and Broca's areas, responsible for interpreting and producing speech. Traditionally, the casting material is some form of rubber or rubber-like material. The openings to the brain cavity, except for the ''foramen magnum'', are closed, and the liquid rubber is slushed around in the empty cranial vault ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rauisuchid
Rauisuchidae is a group of large (up to or more) predatory Triassic archosaurs. There is some disagreement over which genera should be included in Rauisuchidae and which should be in the related Prestosuchidae and Poposauridae, and indeed whether these should even be thought of as separate valid Family (biology), families. Rauisuchids occurred throughout much of the Triassic, and may have first occurred in the Early Triassic if some archosaurian taxa such as ''Scythosuchus'' and ''Tsylmosuchus'' are considered to be within the family. An early cladistic analysis of crocodylotarsan (pseudosuchian) archosaurs included ''Lotosaurus'', ''Fasolasuchus'', ''Rauisuchus'', and "the Kupferzell rauisuchid" (later called ''Batrachotomus'') within Rauisuchidae.Parrish JM. 1993. Phylogeny of the Crocodylotarsi, with reference to archosaurian and crurotarsan monophyly. ''Journal of Vertebrate Paleontology'' 13: 287-308. However, a later study found that ''Batrachotomus'' was a more Basal (phyl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poposaurid
Poposauridae is a family of large carnivorous archosaurs which lived alongside dinosaurs during the Late Triassic. They were around long. Poposaurids are known from fossil remains from North and South America. While originally believed to be theropod dinosaurs (they mirrored the theropods in a number of respects, such as features of the skull and bipedal locomotion), cladistic analysis has shown them to be more closely related to crocodiles. An early cladistic analysis of crocodylotarsan archosaurs included ''Poposaurus'', '' Postosuchus'', '' Teratosaurus'', and '' Bromsgroveia'' within Poposauridae.Parrish JM. 1993. Phylogeny of the Crocodylotarsi, with reference to archosaurian and crurotarsan monophyly. ''Journal of Vertebrate Paleontology'' 13: 287-308. However, later studies found '' Teratosaurus'' to be a rauisuchid.Long RA, Murry PA. 1995. Late Triassic (Carnian and Norian) tetrapods from the Southwestern United States. ''New Mexico Museum of Natural History & Scienc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archosaur
Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avian dinosaurs, pterosaurs, and extinct relatives of crocodilians. Modern paleontologists define Archosauria as a crown group that includes the most recent common ancestor of living birds and crocodilians, and all of its descendants. The base of Archosauria splits into two clades: Pseudosuchia, which includes crocodilians and their extinct relatives, and Avemetatarsalia, which includes birds and their extinct relatives (such as non-avian dinosaurs and pterosaurs). Older definitions of the group Archosauria rely on shared morphological characteristics, such as an antorbital fenestra in the skull, serrated teeth, and an upright stance. Some extinct reptiles, such as proterosuchids and euparkeriids, possessed these features yet originate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
