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Aistopods
Aistopoda (Greek for " avingnot-visible feet") is an order of highly specialised snake-like stegocephalians known from the Carboniferous and Early Permian of Europe and North America, ranging from tiny forms only , to nearly in length. They first appear in the fossil record in the Mississippian period and continue through to the Early Permian. The skull is small but very specialised, with large orbits, and large fenestrae. The primitive form ''Ophiderpeton'' has a pattern of dermal bones in the skull similar in respects to the temnospondyls. But in the advanced genus ''Phlegethontia'' the skull is very light and open, reduced to a series of struts supporting the braincase against the lower jaw, just as in snakes, and it is possible that the aistopods filled the same ecological niches in the Paleozoic that snakes do today. They had an extremely elongated body, with up to 230 vertebrae. The vertebrae were holospondylous, having only a single ossification per segment. They lack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nectridea
Nectridea is an extinct order of lepospondyl tetrapods from the Carboniferous and Permian periods, including animals such as '' Diplocaulus''. In appearance, they would have resembled modern newts or aquatic salamanders, although they are not close relatives of modern amphibians. They were characterized by long, flattened tails to aid in swimming, as well as numerous features of the vertebrae. Description Nectrideans are a diverse group of tetrapods, including the aquatic Urocordylidae, the presumably terrestrial Scincosauridae, and the bizarre horned members of Diplocaulidae (also known as Keraterpetonidae), which includes the "boomerang-headed" ''Diplocaulus'', one of the most famous genera of prehistoric amphibians (in the traditional sense of the word). By the time the earliest known nectrideans appeared in the Late Carboniferous fossil record, they had already diversified into these families, indicating that basal nectrideans are unknown. These different families are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oestocephalus
''Oestocephalus'' is an extinct genus of Aïstopoda, aïstopod tetrapodomorphs that lived during the Carboniferous period. Fossils have been found in the Czech Republic, and in Ohio and Illinois in the United States. It is the type genus of the family (biology), family Oestocephalidae, although it used to be assigned to the family Ophiderpetontidae, which is now considered paraphyletic.Anderson, J. S. (2003). Cranial anatomy of ''Coloraderpeton brilli'', postcranial anatomy of ''Oestocephalus amphiuminus'', and reconsideration of Ophiderpentontidae (Tetrapoda: Lepospondyli: Aistopoda). ''Journal of Vertebrate Paleontology'' 23(3):532-543. It was named by Edward Drinker Cope in 1868 and now contains two species, ''O. amphiuminus'' and ''O. nanum''. See also References Aistopoda Pennsylvanian sarcopterygians of North America Pennsylvanian sarcopterygians of Europe Taxa named by Edward Drinker Cope Fossil taxa described in 1868 {{paleo-tetrapodomorph-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orbit (anatomy)
In anatomy Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ..., the orbit is the Body cavity, cavity or socket/hole of the skull in which the eye and Accessory visual structures, its appendages are situated. "Orbit" can refer to the bony socket, or it can also be used to imply the contents. In the adult human, the volume of the orbit is about , of which the eye occupies . The orbital contents comprise the eye, the Orbital fascia, orbital and retrobulbar fascia, extraocular muscles, cranial nerves optic nerve, II, oculomotor nerve, III, trochlear nerve, IV, trigeminal nerve, V, and abducens nerve, VI, blood vessels, fat, the lacrimal gland with its Lacrimal sac, sac and nasolacrimal duct, duct, the eyelids, Medial palpebral ligament, medial and Lateral palpebral raphe, lateral palpebr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body Of Vertebra
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal segment and the particular species. The basic configuration of a vertebra varies; the vertebral body (also ''centrum'') is of bone and bears the load of the vertebral column. The upper and lower surfaces of the vertebra body give attachment to the intervertebral discs. The posterior part of a vertebra forms a vertebral arch, in eleven parts, consisting of two pedicles (pedicle of vertebral arch), two laminae, and seven processes. The laminae give attachment to the ligamenta flava (ligaments of the spine). There are vertebral notches formed from the shape of the pedicles, which form the intervertebral foramina when the vertebrae articulate. These foramina are the entry and exit conduits for the spinal nerves. The body of the vertebra an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebra
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal segment and the particular species. The basic configuration of a vertebra varies; the vertebral body (also ''centrum'') is of bone and bears the load of the vertebral column. The upper and lower surfaces of the vertebra body give attachment to the intervertebral discs. The posterior part of a vertebra forms a vertebral arch, in eleven parts, consisting of two pedicles (pedicle of vertebral arch), two laminae, and seven processes. The laminae give attachment to the ligamenta flava (ligaments of the spine). There are vertebral notches formed from the shape of the pedicles, which form the intervertebral foramina when the vertebrae articulate. These foramina are the entry and exit conduits for the spinal nerves. The body of the vertebr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudophlegethontia Turnbullorum
''Pseudophlegethontia'' is an extinct genus of aïstopod tetrapodomorphs. It is the only member of the family Pseudophlegethontiidae. The only species is the type species ''P. turnbullorum'', named in 2003. Fossils of ''Pseudophlegethontia'' have been found from the Mazon Creek fossil beds in Grundy County, Illinois, a '' conservation lagerstätte'' well known for the exceptional preservation of middle Pennsylvanian taxa. ''Pseudophlegethontia'' has been considered to be morphologically intermediate between derived phlegethontiids and more basal "ophiderpetontids" such as ''Ophiderpeton''. It possesses basal characters such as a relatively short body, "k shaped" ribs, and distinctive skull roof bones while also possessing several more derived features such as a pointed snout, thin gastralia, and a lack of dorsal osteoderms. It is usually, but not unanimously, placed as the sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Niche
In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another [and] the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts". See also Chapter 2: Concepts of niches, pp. 7 ''ff'' A Grinnellian niche is determined by the habitat in which a species lives and its accompanying Behavioral ecology, behavioral adaptations. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophidia
__FORCETOC__ Ophidia (also known as Pan-Serpentes) is a group of squamate reptiles including modern snakes and reptiles more closely related to snakes than to other living groups of lizards. Ophidia was defined as the "most recent common ancestor of ''Pachyrhachis'' and Serpentes (modern snakes), and all its descendants" by Lee and Caldwell (1998: 1551). The clade name Ophidia derives from the Ancient Greek word (), meaning "small snake". Evolution Modern snakes are thought to have evolved from either burrowing or aquatic lizards during the mid-Cretaceous period, and the earliest known fossils date to around 112 Ma ago. However, the relationship between modern snake and more primitive snake ancestors, many of which retained hind limbs, is less clear. While many of these "stem-snakes" are known from Mesozoic fossils, some of them may be descendants of the earliest true snakes rather than more primitive lineages. Below is a cladogram modified from a study by Wilson ''et al.'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
