Rikunarita-ORG/Wikinium huggingface dataset:
# House mouse

| House mouse |
| --- |
|  |
| Conservation status |
|  Least Concern  (IUCN 3.1) |
| Scientific classification  |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Family: | Muridae |
| Genus: | *Mus* |
| Subgenus: | *Mus* |
| Species: | M. musculus |
| Binomial name |
| Mus musculus Linnaeus, 1758 |
| Subspecies |
| * *Mus musculus bactrianus*
* *Mus musculus castaneus*
* *Mus musculus domesticus*
* *Mus musculus gentilulus*
* *Mus musculus musculus*
 |
|  |
| House mouse range (note: distribution is incomplete) |
| Synonyms |
| *Mus abbotti* |

Notch in upper front teeth
*Mus musculus*
**House mouse** (*Mus musculus*) is the common mouse. It is one of the species of the genus *Mus*. Often, it is just called a mouse. It is a small rodent.

In most parts of the world, they live close to humans. Laboratory mice are types of house mice and are some of the most important organisms used for research in biology and medicine. They are the most commonly used laboratory mammal for experiments.

## Description

They are quite small, but are not the smallest mammals. House mice have an adult body length (nose to base of tail) of 7.5–10 cm (3.0–3.9 in) and a tail length of 5–10 cm (2.0–3.9 in). The weight is typically 10–25 g (0.4–0.9 oz). Usually, house mice are dark beige. Selected strains of mice can be got in other colours.

It is a small, scaly-tailed mouse with a distinct notch in the cutting surface of upper incisors (seen best in side view). Its hair short; ears moderately large and naked.

## Physiology

The main problem of small mammals is their high surface to weight ratio: they have a big surface area for such a small mass. Since heat is radiated from the surface, they have adaptations to help them keep their temperature up to normal. They need to eat frequently, and live in areas where they are protected from the coldest weather. Easy access to high-quality vegetable food (such as grains) and a protected habitat helps them survive and multiply. That is why they are fond of human settlements.

## Life cycle

Their life-span in the wild averages about a year. They are eaten by a variety of small carnivores, but they reproduce rapidly, so that keeps the numbers up. Females have 3–14 babies in a litter, and can have 5 to 10 litters a year. In good conditions, the mouse population rises quickly.

## Habitat

Infestation of mice
Although not native to North America, the house mouse was introduced accidentally to seaport towns. It is now widespread throughout the United States. It occurs either as a commensal or feral animal in practically all parts of the U.S.

As commensal animals, house mice live in close association with man – in houses, outbuildings, stores, and other structures. Where conditions permit, feral mice may be found in fields, along watercourses, and in other places where vegetation is dense enough to hide them.
# Castorimorpha

| Castorimorpha |
| --- |
|  |
| Kangaroo rat |
| Scientific classification |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Rodentia |
| Suborder: | **Castorimorpha** |
| Families |
|
Superfamily Castoroidea:
* Castoridae

Superfamily Geomyoidea:
* Heteromyidae
* Geomyidae
 |

**Castorimorpha** is the suborder of rodents containing the beavers, the pocket gophers, and the kangaroo rats.
# Myr

In writing about prehistory, years are often grouped together in units of one million. **Million years ago** or **megaannum** may be abbreviated as **mya**, **myr** or **Ma**.
# Cretaceous

White cliffs of Dover, made of Jurassic and Cretaceous chalk limestone
The impressive skull of a mosasaur, a giant marine reptile of the Cretaceous.
The **Cretaceous** period is the ninth and longest period in the Phanerozoic eon, lasting 80 million years from 145 to 65 million years ago (mya). It followed the Jurassic period, and is the third and last period of the Mesozoic era. After it came the Cainozoic era.
The Cretaceous period has just two very long epochs:

* Upper Cretaceous 100.5 million years ago (mya) to 65 mya
* Lower Cretaceous 145.5 mya to 100.5 mya.

The Lower Cretaceous at ~45 million years, is the longest epoch in the Phanerozoic eon.

Though famous for its land fauna, the Cretaceous sea level rose much higher than today. North America was partly covered by an epicontinental inland sea, and half of Britain was under water. One account goes as follows: "During the Late Cretaceous (94–64 mya) sea level was up to 650 metres higher than at the start of the Albian, when it was perhaps about the same as it is today... The peak transgressions (sea levels) can be seen world-wide. There were rises of sea level of about 10–90 metres per m.y."

In the Upper Cretaceous, chalk, a type of limestone, was laid down in warm shallow seas. Chalk is 95% to 99% made up of coccoliths, the calcium carbonate (CaCO3) plates which tiny single-celled algae (coccolithophorids) produce.
At its end came the famous meteorite strike which, with the volcanic flood basalts spewed out in the Deccan Plateau (India), ended so many of the dominant life-forms: see K/T extinction event.
# Palaeocene

K/T extinction event recorded in a Wyoming rock (the white stripe in the middle)
The Laramide orogeny was caused by the subduction of oceanic crust under the North American plate
Restoration of a Patagonian landscape during the Palaeocene
The **Palaeocene** is the first geological epoch in the Palaeogene. It was from 66 to 56 million years ago. It started after the end of the Cretaceous, and it was followed by the Eocene epoch.

The word "Palaeocene" may be spelled "Paleocene" quite correctly. It is just an alternative spelling.

The Palaeocene began and ended with an extinction event, each of quite a different character. The epoch began with the K/T extinction event, caused by a combination of a meteorite strike (Chicxulub crater) and a huge volcanic flood basalt eruption. The eruption produced the Deccan Traps in what is now India. This would have caused the extinction of many groups.

The epoch ended with the *Palaeocene–Eocene Thermal Maximum*, a deep ocean anoxic event (DOAE). This means that the ocean depths were lacking oxygen, so no higher forms of life could survive there. This produced a mass extinction of between 35–50% of deep water forms such as benthic foraminifera. At the same time there was a major change of mammalian types on land.

## Climate

After a cooler start, the climate grew warmer during the epoch, far warmer than today, and the world was heavily forested. There were no ice caps at the poles. Warm seas circulated throughout the world, including the poles. The earliest Paleocene featured a low diversity and abundance of marine life, but this trend reversed later in the epoch. Tropical conditions gave rise to abundant marine life, including coral reefs. With the extinction of marine reptiles at the end of the Cretaceous, sharks became the top predators. At the end of the Cretaceous, the ammonites and many species of foraminifera became extinct.

Marine faunas also came to look like modern faunas. Only the marine mammals and an important family of sharks, the Carcharhinidae, are missing.

Non-avian dinosaurs may have survived to some extent into the early Danian stage of the Paleocene Epoch about 66 mya. The controversial evidence for such is a hadrosaur leg bone found from Paleocene strata in New Mexico; but such stray late forms may be derived fossils. This means they were fossilised, then erosion uncovered them, then they were buried again in a younger layer of rocks.

## Polar forests

The warm Paleocene climate, much like that of the Cretaceous, supported polar forests. Rainfall is a major factor in plant diversity nearer the equator, but polar plants have to adapt to light (polar nights and midnight suns) and temperature. Because of this, plants from both poles evolved some similar characteristics, such as broad leaves. Plant diversity at both poles increased throughout the Paleocene, especially at the end, with the increasing global temperature.

## Stages of the Palaeocene

The Palaeocene is divided into three stages:

| Stage | Time: million years ago |
| --- | --- |
| Thanetian | 59.2 – 56 |
| Selandian | 61.6 – 59.2 |
| Danian | 66 – 61.6 |
# Eocene

The **Eocene** was the second geological epoch in the Palaeogene, and by far the longest. It began 56 million years ago, and ended 33.9 million years ago with a global warming crisis. Before the period was the Palaeocene, and after the time was the Oligocene, the time where paraceratheres, indricotheres, entelodonts, hyaenodonts, archaeotheres, chalicotheres, arsinoitheres and cynodictids were the main animals.

The Eocene, like the Palaeocene before it, had a climate much warmer than today. At the start of the Eocene, the *Palaeocene–Eocene Thermal Maximum* was reached. This lasted for 100,000 years, and caused a large extinction event. The land was heavily forested, with temperate forests into Arctic and Antarctic regions. The many herbivorous mammals were browsers, not grazers. All the members of the new mammal orders were small, under 10 kg. Eocene mammals were only 60% of the size of the primitive Palaeocene mammals that came before them. They were also smaller than the mammals that followed them. The main animals of the time included *Propalaeotherium*, *Leptictidium*, *Ambulocetus*, *Pristichampsus*, *Gastornis* and *Hyracotherium*.

The end of the Eocene was the beginning of the Oligocene (33.9 million years ago). Many plant and animal species went extinct. This was the Eocene–Oligocene extinction event. The extinction event was probably caused by meteorite strikes in Siberia and Chesapeake Bay. The fauna of this timeline included basilosaurs, arsinoitheres, dorudonts, andrewsarchids, paraceratheres, indricotheres, uintatheres, hyaenodonts, embolotheres, brontotheres and moeritheres.

## Swamp forests

Tropical peatlands coexist with swamp forests in the Eocene. This is the most recent period which has left us coal measures. It was so hot in the Eocene that there was a high level of plant growth. Polar forests were quite extensive. Fossils and preserved remains of trees such as swamp cypress and dawn redwood from the Eocene have been found on Ellesmere Island in the Arctic.

The end-Eocene flora and some of its fauna is well seen at Florissant Fossil Beds National Monument, Rocky Mountains, Colorado.
# Oligocene

The North Atlantic was narrow, during the Oligocene
The **Oligocene** is the last geological epoch in the Palaeogene. It lasted for about 11 million years, from 34 million years ago to 23 million years ago. It was preceded by the Eocene and followed by the Miocene. During the Oligocene, the world continued to get cooler from its peak in the mid-Eocene. The world was still largely forested, but grasslands began to spread. Ice formed in Antarctica. The period is seen as one of *transition*, both in climate and in the biota.
# Pliocene

The **Pliocene** (**Pleiocene** in older texts) was a short geological epoch at the end of the Neogene period. It was the fifth and final epoch of the former Tertiary period and the fifth epoch of the Cainozoic era. It began 5.3 million years ago and ended 2.6 million years ago. The Pliocene follows the Miocene epoch and is followed by the Pleistocene epoch.

The world continued to get cooler and drier in the Pliocene. Tropical rain forests and deciduous forests shrank. Grasslands grew, and many herbivorous mammals became grazers instead of browsers. Of this we are certain, because their teeth tell us what kind of food they ate. Browsers eat leaves and small branches, and grazers eat grass. The concept of *mesowear* deals with this. Mesowear is a method based on animals' tooth wear fingerprints. Each animal has special feeding habits, which cause unique tooth wear. Rough feeds cause serious tooth abrasion, while smooth one triggers moderate abrasion. So browsers have teeth with moderate abrasion and grazers have teeth with rough abrasion. Seeing the teeth of browsers next to those of grazers is convincing.

A new land bridge at Panama brought a Great American Interchange. Hominid evolution took a new turn as some apes started to live on the savannah instead of the forests (Australopithecines). Late in the Pliocene the Greenland ice cap grew and became permanent, and the ice sheet of Antarctica grew to cover most of Antarctica.

## Gallery

* The gastropod *Aporrhais* from the Pliocene of Cyprus.
* Aspa marginata
* Carcharodon subauriculatus

## Related pages

* Human timeline
# Pleistocene

*"The Ice Age" redirects here. For other uses, see Ice Age (disambiguation).*
Glyptodon - an old type of an animal related to the armadillo. It lived in South America during the Pleistocene.
A model of a mammoth - a hairy elephant that lived in the frozen north. The last mammoth died about 4,500 years ago.
The **Pleistocene** stage or epoch was a long period of time. It stretched from 2.58 million years ago to 11,700 years ago. It is the first epoch of the Quaternary period and the sixth in the Cainozoic. It came after the Pliocene epoch, and before the modern-day Holocene.

## Ice ages

The Pleistocene was a time of ice ages: cold glacial periods with shorter, warmer, interglacials. During these ice ages, the world became much colder for a long time.

For much of the 20th century, geologists believed there were four "major" ice ages. Nowadays scientists think there were at least five.

During these glaciations, much of the world we know was covered by ice: North America down to and past the Great Lakes; all of northern Russia and Europe; and England down to the Thames.

## Animals

Many animals that lived during the Pleistocene have become extinct because of climate change and hunting by humans.

Many Pleistocene mammals were larger, cold-adapted versions of animals that live now. Mammoths were a species of elephant in the ice age. Their popular name of woolly mammoth suggests the long hair which was an adaptation to the cold.

Glyptodon was something like a giant armadillo.

## Ancient humans

Ancient human species lived during the Pleistocene. In Europe and Asia the large-brained Neanderthal (*Homo neanderthalensis*) lived until about 30,000 years ago. Modern man did not descend from Neanderthals, but originated in Africa from another branch of the genus *Homo*.

## Related pages

* Ice age
* Global warming
* Human evolution
* Human timeline
* Palaeolithic
# Holocene

Temperature variations during the Holocene
Paleogeographic reconstruction of the North Sea appr. 9000 years ago during the young Holocene and after the end of the last ice age.
The **Holocene** is the present geological epoch. It started around 11,000 years ago after the last ice age. We are now in a relatively warm climate in Earth's history.

This is the second epoch of the Quaternary and the seventh of the Cainozoic.

## Origin of name (or etymology)

*Holocene* comes from two Ancient Greek words.

The name was suggested by the French palaeontologist and entomologist Paul Gervais (d. 1879); It is supposed to mean that the present time is part of the 'entirely new' epoch, or the "Holocene [epoch]".

## Holocene climatic optimum

The **Holocene climatic optimum** (HCO) was a warm period from about 9,000 to 5,000 years BP. The interesting thing about this is, despite recent global warming, we are still below this warm period (see diagram).

The warm period was followed by a gradual decline until about two millennia ago.

### More details

The Holocene is also called the **Recent** epoch. It is the second stage in the Quaternary period.

The Holocene marks the end of the previous series of ice ages in the Pleistocene. About 11,700 years ago the temperatures rose quickly from the previous level.

During the early Holocene, there were many extinctions amongst larger mammals. This is because of human hunting and climate change.

At this time the Bering bridge connecting Russia and Alaska melted. Also the land bridge between China and Japan melted (starting the Jomon period), as well as many land bridges between islands in Southeast Asia.
# Superclass (biology)

A **superclass** is a level in the Linnaean taxonomy for biology. Normally the classification of a phylum runs phylum > class > order etc. Sometimes steps are needed between the main terms. A superclass is composed of one or more classes, and ranks below a subphylum. The tetrapods, for example, are part of the subphylum of vertebrates.