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Gorgonopsia
Gorgonopsia (from the Greek Gorgon, a mythological beast, and 'aspect') is an extinct clade of Saber-toothed predator, sabre-toothed therapsids from the Middle Permian, Middle to the Upper Permian, roughly between 270 and 252 million years ago. They are characterised by a long and narrow skull, as well as elongated upper and sometimes lower canine teeth and incisors which were likely used as slashing and stabbing weapons. Postcanine teeth are generally reduced or absent. For hunting large prey, they possibly used a bite-and-retreat tactic, ambushing and taking a debilitating bite out of the target, and following it at a safe distance before its injuries exhausted it, whereupon the gorgonopsian would grapple the animal and deliver a killing bite. They would have had an exorbitant gape, possibly in excess of 90°, without having to unhinge the jaw. They markedly increased in size as time went on, growing from small skull lengths of in the Middle Permian to bear-like proportions of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inostrancevia
''Inostrancevia'' is an extinction, extinct genus of large carnivorous therapsids which lived during the Late Permian in what is now European Russia and Southern Africa. The first-known fossils of this gorgonopsian were discovered in the context of a long series of excavations carried out from 1899 to 1914 in the Northern Dvina, Russia. Among these are two near-complete skeletons embodying the first described specimens of this genus, being also the first gorgonopsian identified in Russia. Several other fossil materials were discovered there, and the various finds led to confusion as to the exact number of valid species, before only two of them were formally recognized, namely ''I. alexandri'' and ''I. latifrons''. A third species, ''I. uralensis'', was erected in 1974, but the fossil remains of this taxon are very thin and could come from another genus. More recent research carried out in Southern Africa has discovered specimens identified as belonging to this genus, with the spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saber-toothed Predator
A saber-tooth (alternatively spelled sabre-tooth) is any member of various extinct groups of predatory therapsids, predominantly carnivoran mammals, that are characterized by long, curved saber-shaped canine teeth which protruded from the mouth when closed. Among the earliest animals that can be described as "sabertooths" are the gorgonopsids, a group of non-mammalian therapsids that lived during the Middle-Late Permian, around 270-252 million years ago. Saber-toothed mammals have been found almost worldwide from the Eocene epoch to the end of the Pleistocene epoch (42 million years ago – 11,000 years ago). One of the best-known genera is the machairodont or "saber-toothed cat" ''Smilodon'', the species of which, especially ''S. fatalis'', are popularly referred to as "saber-toothed tigers", although they are not closely related to tigers (''Panthera''). Despite some similarities, not all saber-tooths are closely related to saber-toothed cats or felids in-general. Instead, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Therocephalia
Therocephalia is an extinct clade of therapsids (mammals and their close extinct relatives) from the Permian and Triassic periods. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians were once described as "mammal-like reptiles". Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals. Indeed, it had been proposed that therocephalians themselves may have given rise to the cynodonts, and therefore that therocephalians as recognised are paraphyletic in relation to cynodonts and so not a clade. Conventionally, however, Therocephalia is regarded as the sister clade of Cynodontia, together forming the clade Eutheriodontia. The close relationship of Therocephalia to Cynodontia takes evidence in a variety of skeletal features. Most notable is that the skull roof is narrowed between two enlarged ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubidgeinae
Rubidgeinae is an extinct subfamily of gorgonopsid therapsids known only from Africa. They were among the largest gorgonopsians, and their fossils are common in the Cistecephalus and Daptocephalus assemblage zones of the Karoo Basin. They lived during the Late Permian, and became extinct at the end of the Permian. Description Rubidgeines were large, quadrupedal carnivores of the family Gorgonopsidae. Their largest teeth are their upper canines, which were blade-like and had well-developed serrations. Their postcanine teeth were small and conical, but were also frequently serrated. Tooth replacement was rapid relative to basal therocephalians. Rubidgeines can be distinguished from other gorgonopsians by the absence of a blade-like parasphenoid bone and reduced or absent preparietal bone. The jugal bone, while narrow in most gorgonopsians, was often broadly expanded in rubidgeines. The largest rubidgeins were '' Dinogorgon'' and '' Rubidgea''. Paleobiology Rubidgeines were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harry Govier Seeley
Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist. Early life Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his father was declared bankrupt, Seeley was sent to live with a family of piano makers. Between the ages of eleven and fourteen, he went to a day school and then spent the next two years learning to make pianos. He also attended lectures at the Royal School of Mines by Thomas Henry Huxley, Edward Forbes, and other notable scientists. In 1855, with the support of his uncle, Seeley began to study law but shortly gave it up to pursue a career as an actuary. In the late 1850s, he studied English and mathematics at the Working Men's College and served as a secretary for the college's museum. He also worked in the library of the British Museum, where Samuel Pickworth Woodward encouraged him to study geology. In 1859, Seeley began studies at Sidney ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homeothermy
Homeothermy, homothermy, or homoiothermy () is thermoregulation that maintains a stable internal body temperature regardless of external influence. This internal body temperature is often, though not necessarily, higher than the immediate environment. Homeothermy is one of the 3 types of thermoregulation in warm-blooded animal species. Homeothermy's opposite is poikilothermy. A poikilotherm is an organism that does not maintain a fixed internal temperature but rather its internal temperature fluctuates based on its environment and physical behaviour. Homeotherms are not necessarily endothermic. Some homeotherms may maintain constant body temperatures through behavioral mechanisms alone, ''i.e.'', behavioral thermoregulation. Many reptiles use this strategy. For example, desert lizards are remarkable in that they maintain near-constant activity temperatures that are often within a degree or two of their lethal critical temperatures. Evolution Origin of homeothermy The evol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binocular Vision
Binocular vision is seeing with two eyes. The Field_of_view, field of view that can be surveyed with two eyes is greater than with one eye. To the extent that the visual fields of the two eyes overlap, #Depth, binocular depth can be perceived. This allows objects to be recognized more quickly, camouflage to be detected, spatial relationships to be perceived more quickly and accurately (#Stereopsis, stereopsis) and perception to be less susceptible to optical illusions, optical illusions. In secion #Medical, Medical attention is paid to the occurrence, defects and sharpness of binocular vision. In section #Biological, Biological the occurrence of binocular vision in animals is described. Geometric terms When the left eye (LE) and the right eye (RE) observe two objects X and Y, the following concepts are important:Krol J.D.(1982),"Perceptual ghosts in stereopsis, a ghosly problem in binocular vision", PhD thesis ISBN 90-9000382-7.Koenderink J.J.;van Doorn A.J. (1976) "Geometry of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nocturnal
Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatures generally have highly developed senses of hearing (sense), hearing, olfaction, smell, and specially adapted eyesight. Some animals, such as ferrets, have eyes that can adapt to both low-level and bright day levels of illumination (see metaturnal). Others, such as bushbaby, bushbabies and (some) bats, can function only at night. Many nocturnal creatures including tarsier, tarsiers and some owl, owls have large eyes in comparison with their body size to compensate for the lower light levels at night. More specifically, they have been found to have a larger cornea relative to their eye size than diurnal creatures to increase their : in the low-light conditions. Nocturnality helps wasps, such as ''Apoica flavissima'', avoid hunting in intens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crepuscular Animal
In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal (active during dawn), vespertine/vespertinal (active during dusk), or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daytime and of night, respectively. Some crepuscular animals may also be active by moonlight or during an overcast day. Matutinal animals are active only after dawn, and vespertine only before dusk. A number of factors affect the time of day an animal is active. Predators hunt when their prey is available, and prey try to avoid the times when their principal predators are at large. The temperature may be too high at midday or too low at night. Some creatures may adjust their activities depending on local competition. Etymology and usage The word ''crepuscular'' derives from the Latin '' crepusculum'' ("twilight"). Its sense accordingly differs from diurnal and nocturnal behavior, whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diurnality
Diurnality is a form of plant and ethology, animal behavior characterized by activity during daytime, with a period of sleeping or other inactivity at night. The common adjective used for daytime activity is "diurnal". The timing of activity by an animal depends on a variety of environmental factors such as the temperature, the ability to gather food by sight, the risk of predation, and the time of year. Diurnality is a cycle of activity within a 24-hour period; cyclic activities called circadian rhythms are endogenous cycles not dependent on external cues or environmental factors except for a zeitgeber. Animals active during twilight are crepuscular, those active during the night are nocturnal and animals active at sporadic times during both night and day are cathemerality, cathemeral. Plants that open their flowers during the daytime are described as diurnal, while those that bloom during nighttime are nocturnal. The timing of flower opening is often related to the time at whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three Evolution of mammalian auditory ossicles, middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors Genetic divergence, diverged in the Carboniferous Period over 300 million years ago. Around 6,640 Neontology#Extant taxon, extant species of mammals have been described and divided into 27 Order (biology), orders. The study of mammals is called mammalogy. The largest orders of mammals, by number of species, are the rodents, bats, and eulipotyphlans (including hedgehogs, Mole (animal), moles and shrews). The next three are the primates (including humans, monkeys and lemurs), the Artiodactyl, even-toed ungulates (including pigs, camels, and whales), and the Carnivora (including Felidae, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reptile
Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocephalia. About 12,000 living species of reptiles are listed in the Reptile Database. The study of the traditional reptile orders, customarily in combination with the study of modern amphibians, is called herpetology. Reptiles have been subject to several conflicting Taxonomy, taxonomic definitions. In Linnaean taxonomy, reptiles are gathered together under the Class (biology), class Reptilia ( ), which corresponds to common usage. Modern Cladistics, cladistic taxonomy regards that group as Paraphyly, paraphyletic, since Genetics, genetic and Paleontology, paleontological evidence has determined that birds (class Aves), as members of Dinosauria, are more closely related to living crocodilians than to other reptiles, and are thus nested among re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
