Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels, chipmunks, marmots, flying squirrels, and prairie dogs amongst other rodents. Squirrels are indigenous to the Americas, Eurasia, and Africa, and were introduced by humans to Australia. The earliest known fossilized squirrels date from the Eocene epoch, and among other living rodent families, the squirrels are most closely related to the mountain beaver and to the dormice.
In biology, taxonomy is the science of naming, defining (circumscribing) and classifying groups of biological organisms on the basis of shared characteristics. Organisms are grouped together into taxa and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a super-group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum, class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms.
A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.
Binomial nomenclature, also called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name, a binomen, binominal name or a scientific name; more informally it is also called a Latin name.
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" after a period of apparent absence.
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biological species. It uses a set of criteria to evaluate the extinction risk of thousands of species and subspecies. These criteria are relevant to all species and all regions of the world. With its strong scientific base, the IUCN Red List is recognized as the most authoritative guide to the status of biological diversity. A series of Regional Red Lists are produced by countries or organizations, which assess the risk of extinction to species within a political management unit.
A petasos or petasus is a sun hat of Thessalian origin worn by ancient Greeks, Macedonians, Thracians and Etruscans, often in combination with the chlamys cape. It was usually made of wool felt, leather or straw, with a broad, floppy brim. It was worn primarily by farmers and travellers, and was considered characteristic of rural people. As a winged hat, it became the symbol of Hermes, the Greek mythological messenger god.
Endemism is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the orange-breasted sunbird is exclusively found in the fynbos vegetation zone of southwestern South Africa and the glacier bear is endemic to Southeast Alaska. The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range. An alternative term for a species that is endemic is precinctive, which applies to species that are restricted to a defined geographical area.
The conservation status of a group of organisms indicates whether the group still exists and how likely the group is to become extinct in the near future. Many factors are taken into account when assessing conservation status: not simply the number of individuals remaining, but the overall increase or decrease in the population over time, breeding success rates, and known threats. Various systems of conservation status exist and are in use at international, multi-country, national and local levels as well as for consumer use.
The tomb of the Etruscan king Lars Porsena is a legendary ancient building in what is now central Italy. Allegedly built around 500 BCE at Clusium, and was described as follows by the Roman writer Marcus Varro :
Porsena was buried below the city of Clusium in the place where he had built a square monument of dressed stones. Each side was three hundred feet in length and fifty in height, and beneath the base there was an inextricable labyrinth, into which, if any-body entered without a clue of thread, he could never discover his way out. Above this square building there stand five pyramids, one at each corner and one in the centre, seventy-five feet [c. 22 meters] broad at the base and one hundred and fifty feet [c. 44 meters] high. These pyramids so taper in shape that upon the top of all of them together there is supported a brazen globe, and upon that again a petasus from which bells are suspended by chains. These make a tinkling sound when blown about by the wind, as was done in bygone times at Dodona. Upon this globe there are four more pyramids, each a hundred feet [c. 30 meters] in height, and above them is a platform on which are five more pyramids.
Armsia is a genus of small, air-breathing, land snails, terrestrial pulmonate gastropod mollusks in the family Amastridae.
Sepiolina is a small genus of bobtail squid in the family Sepiolidae and the subfamily Heteroteuthidinae from the western Pacific Ocean.
An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and invasive species. The International Union for Conservation of Nature (IUCN) Red List lists the global conservation status of many species, and various other agencies assess the status of species within particular areas. Many nations have laws that protect conservation-reliant species which, for example, forbid hunting, restrict land development, or create protected areas. Some endangered species are the target of extensive conservation efforts such as captive breeding and habitat restoration.
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined.
Antedon is a genus of free-swimming, stemless crinoids. The genus first appeared in the fossil record in the Cretaceous period.
Antedon petasus is a marine invertebrate, a species of crinoid or feather star in the family Antedonidae. It is found around the coasts of north west Europe.
Discotectonica is a genus of sea snails, marine gastropod mollusks in the family Architectonicidae, the staircase shells or sundials.
The Dinos of the Gorgon Painter is an important example of ancient Greek pottery, produced at Athens around 580 BC. It entered the Louvre's collection in 1861, with the purchase of Giampietro Campana's collection.
