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Formation (stratigraphy)
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness (geology), thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diprionomys
''Diprionomys'' is an extinct genus of Heteromyidae that existed in the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ... during the Late Miocene period. References Heteromyidae Miocene rodents Neogene mammals of North America Fossil taxa described in 1910 {{Heteromyidae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vespertilionidae
Vespertilionidae is a family of microbats, of the order Chiroptera, flying, insect-eating mammals variously described as the common, vesper, or simple nosed bats. The vespertilionid family is the most diverse and widely distributed of bat families, specialised in many forms to occupy a range of habitats and ecological circumstances, and it is frequently observed or the subject of research. The facial features of the species are often simple, as they mainly rely on vocally emitted echolocation. The tails of the species are enclosed by the lower flight membranes between the legs. Over 300 species are distributed all over the world, on every continent except Antarctica. It owes its name to the genus ''Vespertilio'', which takes its name from a word for bat, ', derived from the Latin term ' meaning 'evening'; they are termed "evening bats" and were once referred to as "evening birds". (The term "evening bat" also often refers more specifically to one of the species, '' Nycticeius humer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perognathinae
Perognathinae is a subfamily of rodents consisting of two genera of pocket mice. Most species live in complex burrows within the deserts and grasslands of western North America, They feed mostly on seeds and other plant parts, which they carry in their fur-lined cheek pouches to their burrows. Description There are about twenty-six members of the subfamily Perognathinae divided among two genera. They are all small rodents. Adaptations include partially fused vertebrae in the neck, short fore limbs and much enlarged bullae (bubble-shaped bones in the skull). The dental formula is 1/1, 0/0, 1/1, 3/3 making twenty teeth in total. The molars have two-lobed cusps. The upper incisors are grooved and the enamel on the molars is quickly worn away by chewing leaving the dentine exposed. The check teeth have roots. Fur-lined cheek pouches are a feature across the family Heteromyidae. They have openings near the mouth and extend backwards along the sides of the neck. The fur on the animal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camelidae
Camelids are members of the biological family Camelidae, the only currently living family in the suborder Tylopoda. The seven extant members of this group are: dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas, and guanacos. Camelids are even-toed ungulates classified in the order Cetartiodactyla, along with species like whales, pigs, deer, cattle, and antelopes. Characteristics Camelids are large, strictly herbivorous animals with slender necks and long legs. They differ from ruminants in a number of ways.Fowler, M.E. (2010). ''Medicine and Surgery of Camelids'', Ames, Iowa: Wiley-Blackwell. Chapter 1 "General Biology and Evolution" addresses the fact that camelids (including camels and llamas) are not ruminants, pseudo-ruminants, or modified ruminants. Their dentition show traces of vestigial central incisors in the incisive bone, and the third incisors have developed into canine-like tusks. Camelids also have true canine teeth and tusk-lik ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermophilus
''Spermophilus'' is a genus of ground squirrels in the Sciuridae, squirrel family. As traditionally defined the genus was very species-rich, ranging through Europe, Asia and North America, but this arrangement was found to be paraphyletic to the certainly distinct prairie dogs, marmots, and antelope squirrels. As a consequence, all the former ''Spermophilus'' species of North America have been moved to other genera, leaving the European and Asian species as true ''Spermophilus'' (the only exceptions are two Asian ''Urocitellus''). Some species are sometimes called susliks (or sousliks). This name comes from Russian :ru:Суслики, суслик, ''suslik''. In some languages, a derivative of the name is in common usage, for example ''suseł'' in Polish. The scientific name of this genus means "seed-lovers" (gr. σπέρμα ''sperma'', genitive σπέρματος ''spermatos'' – seed; φίλος ''philos'' – friend, lover). Habitat and behavior As typical ground squirr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scapanus
''Scapanus'' is a genus of moles in the family Talpidae. They live in North America from west of the Rockies south to Baja California del Norte, and north to British Columbia, wherever conditions permit a mole population; that is to say, apart from the most sandy, rocky, or developed places. As they are one genus, they are very closely related, but as species, they rarely if ever interbreed successfully. It contains the following living species: * Mexican mole (''S. anthonyi'') * Northern broad-footed mole (''S. latimanus'') * Southern broad-footed mole (''S. occultus'') * Coast mole (''S. orarius'') * Townsend's mole (''S. townsendii'') In addition, there are several extinct species known from fossils. *''Scapanus hagermanensis'' ( Mid Blancan stage, Idaho) *''Scapanus malatinus'' ( Blancan- Quaternary, California). *''Scapanus proceridens'' (Miocene, Oregon and Idaho) *''Scapanus shultzi'' (Miocene, California and Oregon) Distribution Townsend's mole is primarily a Cal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pliohippus
''Pliohippus'' (Greek (, "more") and (, "horse")) is an extinct genus of Equidae, the "horse family". ''Pliohippus'' arose in the middle Miocene, around 15 million years ago. The long and slim limbs of ''Pliohippus'' reveal a quick-footed steppe animal. While some specimens have one toe per leg, others have three (the main toe and two non-functional side toes). Until recently, because of its many anatomical similarities, ''Pliohippus'' was believed to be the ancestor of the present-day horse and its relatives in '' Equus''. Although ''Pliohippus'' clearly is an equid and thus related to ''Equus'', its skull had deep facial ''fossae'', a feature not found in any member of ''Equus''. Additionally, its teeth were strongly curved, unlike the very straight teeth of modern horses. Consequently, it is unlikely to be the ancestor of the modern horse; instead, it is likely to be the ancestor of ''Astrohippus''.MacFadden, B. J. (1984). "Astrohippus and Dinohippus". ''J. Vert. Paleon''. 4( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peromyscus
''Peromyscus'' is a genus of rodents. They are commonly referred to as deer mice or deermice, not to be confused with the chevrotain or "mouse deer". They are New World mice only distantly related to the common house and laboratory mouse, ''Mus musculus''. From this relative, ''Peromyscus'' species are distinguished by relatively larger eyes, and also often two-tone coloring, with darker colors over the dorsum (back), and white abdominal and limb hair-coloring. In reference to the coloring, the word ''Peromyscus'' comes from Greek words meaning "booted mouse". They are also accomplished jumpers and runners by comparison to house mice, and their common name of "deer mouse" (coined in 1833) is in reference to this agility. The most common species of deer mice in the continental United States are two closely related species, '' P. maniculatus'' and '' P. leucopus''. In the United States, ''Peromyscus'' is the most populous mammalian genus overall, and has become notorious in the w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypolagus
''Hypolagus'' is an extinct genus of lagomorph, first recorded in the Hemingfordian (early to middle Miocene) of North America. It entered Asia during the early Turolian and spread to Europe not much later, where it survived until the Middle Pleistocene. Though unknown in the Iberian Peninsula, fossils of this genus have been found in the Balearic Islands, suggesting an eastern migration during the dry period in the Mediterranean region known as the Messinian Salinity Crisis.Quintana et al. (2010) "Presence of ''Hypolagus'' Dice, 1917 (Mammalia, Lagomorpha) in the Neogene of the Balearic Islands (Western Mediterranean): Description of ''Hypolagus balearicus'' nov. sp.". Geobios 43, 555-567 ''Hypolagus'' generally shows features intermediate between rabbits and hares. ''Hypolagus balearicus'' was the smallest species at and showed several peculiar features, such as short elbow-to-humerus ratio and robustness of the ulna. Species Many species of ''Hypolagus'' have been described, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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