Naturally, higher categories such as genera, families, orders, classes and phyla last longer, because they are composed of more species. As far as we know, no phylum has gone completely extinct since the Cambrian, but quite a few classes went extinct in one or other of the 'big five' extinction events. Examples of higher categories of animal now extinct are: placoderm fish, trilobites, ammonites, pelycosaurs, non-avian dinosaurs, pterosaurs, ichthyosaurs and plesiosaurs.
Darwin thought that most extinctions occurred because some organisms became more effective, and replaced their less advanced competitors. No doubt that does occur, but the view now is that environmental change is more important. Organisms become adapted to the environments they live in. The environment certainly does change, and sometimes quite dramatically. When it does, some organisms can adapt to the changes. Others cannot.
The Earth's environment can stay rather stable for long periods of time. Then the rate of extinction is usually quite low. Then changes occur, sometimes quite rapidly. In these times the rate of extinction can be much higher. The rate of extinction is therefore a useful thing to measure.
Minehead
Minehead is a seaside town and civil parish in Somerset, England. It is in the borough of Somerset West and Taunton.
In 2011, the town had a population of 11,981. It is close to the border with Devon.
The town is 21 miles (34 km) north-west of Taunton, Somerset's county town.
It is close to the Exmoor National Park.
Minehead is famous for being the location of Butlin's Minehead, a popular holiday camp owned by Butlin's.
The town is the starting point of the South West Coast Path, the longest countryside walking trail in the United Kingdom.
Minehead has one twin town. It is twinned with:
Hank Azaria
Henry Albert "Hank" Azaria ( ; born April 25, 1964) is an American actor, voice actor, comedian and producer. He voiced many characters in the Fox animated television series "The Simpsons". He also appeared in movies such as "The Birdcage" (1996), and on stage as Sir Lancelot in the Monty Python-inspired musical, "Spamalot". He married Helen Hunt from 1999 to 2000. Azaria makes a relationship with Katie Wright. He starred in Showtime's original series "Huff".
Mexico City
Mexico City () is the capital and largest city of Mexico. It is also one of the most populous and polluted cities in the world. The Aztec people were here before the Spanish came and made Mexico City. It was founded in 1521 by Hernán Cortés. Today, about 8.5 million people live in the city, and about 18 million live in the Greater Mexico City urban area. The city of Mexico City ceased to exist in 1928. Since then, there is only the Federal District.
Mexico City has 18.1 million people. It is the city with the second highest number of people in the world after Tokyo in Japan and just slightly more populated than Mumbai in India.
Mexico City was first built in the 1520s after Hernán Cortés destroyed the Aztec city of Tenochtitlan. The Spaniards then emptied the basin of Lake Texcoco to keep it from flooding. By the late 1700s, Mexico City had over 100,000 people. However, there were many slums, which caused epidemics. There were political problems in the mid 1800s after Mexico became independent. More than 40 people ruled in the 40 years after the country became independent. In the late 1800s and early 1900s, electric light and gas were brought to the city. But there was a big difference between the rich western part of the city and the poor eastern part of the city. By 1930, Mexico City had 1,000,000 people. The city kept growing quickly. In 1968, the Olympic Games were in Mexico City. In 1985, an earthquake hit the capital. In the past few decades, there have been problems with crime and corruption.
Mexico City has a high population density. It is also surrounded by mountains. This causes problems with air pollution.
Sometimes Mexico City gets earthquakes.
Mexico City is in the Valley of Mexico at around 2,300 meters (7,800 feet) above sea level.
Mexico City its divided by 16 boroughs: Álvaro Obregón, Azcapotzalco, Benito Juarez, Coyoacán, Cuajimalpa, Cuauhtémoc, Gustavo A. Madero, Iztacalco, Iztapalapa, Magdalena Contreras, Miguel Hidalgo, Milpa Alta, Tláhuac, Tlalpan, Venustiano Carranza and Xochimilco.
Mexico City was originally built on a lake, Lake Texcoco, which is now mostly drained. The ecology of the area has been much changed by the draining. Many of its native species, such as the Axolotl, are extinct, or endangered.
The mountains Popocatépetl and Iztaccíhuatl are nearby.
Mexico City is in the tropics. But because its elevation is so high, it has a subtropical highland climate ("Cwb" in the Köppen climate classification). This means temperatures are warm or mild year-round. It is a lot wetter in the summer than in the winter. Some parts of the city get frost in the winter.
1821
John Hinckley Jr.
John Warnock Hinckley, Jr. (born May 29, 1955) is the man who attempted to assassinate President Ronald Reagan. On March 30, 1981, shortly after Reagan was elected, Hinckley shot at Reagan in Washington, D.C. Reagan was injured, but recovered quickly. Hinckley was tried, but was found not guilty, due to his insanity. He said the reason he shot the President was to get the attention of actress Jodie Foster, of whom he was a fan.
Hinckley has schizophrenia, dysthymia, narcissistic personality disorder and schizoid personality disorder. He also has borderline and passive-aggressive features. He was born in Ardmore, Oklahoma.
Tampico, Illinois
Tampico is a village in Whiteside County, Illinois. The 2000 census said the village had a total population of 772.
On February 6, 1911, Ronald Reagan, who used to be President of the United States (1981-1989) was born in a two story apartment over the local bank. The building where the apartment is near the main street (Illinois Highway 172). Reagan was born in the front bedroom of the apartment.
Tampico is located at 41°37'50" North, 89°47'8" West (41.630559, -89.785573).
The United States Census Bureau says the village has a total area of 1.0 km² (0.4 mi²). None of it is water-covered.
Tampico is about 50 miles east of the Quad Cities (the cities of Davenport, Bettendorf, Iowa, Moline and Rock Island, Illinois). It's about 130 miles west of Chicago.
The census of 2000 says there are 772 people, 292 households, and 205 families living in the village. The population density is 745.2/km² (1,941.3/mi²). There are 315 houses at an average density of 304.1/km² (792.1/mi²). The village is 99.74% White.
There are 292 households out of which 33.2% have children under the age of 18 living with them, 57.2% are married couples living together, 9.2% is a single women, and 29.5% are not families. 24.7% of all households are made up of individuals and 13.0% have someone living alone who is 65 years of age or older. The average household size is 2.64 and the average family size is 3.1.
In the village the population is spread out with 28.9% under the age of 18, 7.9% from 18 to 24, 26.2% from 25 to 44, 23.6% from 45 to 64, and 13.5% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 102.1 males. For every 100 females age 18 and over, there are 102.6 males.
The average income for a household in the village is $40,221, and the average income for a "family" is $43,646. Males have an average income of $30,667 versus $18,409 for females. The per person income for the village is $14,467. 8.5% of the population and 6.4% of families are below the poverty line. Out of the total population, 10.2% of those under the age of 18 and 4.6% of those 65 and older are living below the poverty line.
The city was also the birthplace of Admiral Joseph M. Reeves.
Surface area