background preloader

BBC Nature - History of life on Earth

BBC Nature - History of life on Earth
Pangea supercontinent from space, as it may have looked 300 million years ago. The Earth is a little over 4.5 billion years old, its oldest materials being 4.3 billion-year-old zircon crystals. Its earliest times were geologically violent, and it suffered constant bombardment from meteorites. When this ended, the Earth cooled and its surface solidified to a crust - the first solid rocks. There were no continents as yet, just a global ocean peppered with small islands. Erosion, sedimentation and volcanic activity - possibly assisted by more meteor impacts - eventually created small proto-continents which grew until they reached roughly their current size 2.5 billion years ago. The history of life on Earth began about 3.8 billion years ago, initially with single-celled prokaryotic cells, such as bacteria. View the Tree of Life Jump to: Geological timeline | Geological time periods | Big Five mass extinction events | Mass extinction theories | Ancient Earth habitats Geological timeline

Related:  0021 Understand the fundamental concepts and principles of EarthFossils

Geological History of Earth Home > Earth > Plate Tectonics > Geologic History of Earth How Old is the Earth? In the very beginning of earth's history, this planet was a giant, red hot, roiling, boiling sea of molten rock - a magma ocean. The heat had been generated by the repeated high speed collisions of much smaller bodies of space rocks that continually clumped together as they collided to form this planet. Origins of the Universe, Big Bang Theory Information, Big Bang Facts, News, Photos The most popular theory of our universe's origin centers on a cosmic cataclysm unmatched in all of history—the big bang. This theory was born of the observation that other galaxies are moving away from our own at great speed, in all directions, as if they had all been propelled by an ancient explosive force. Before the big bang, scientists believe, the entire vastness of the observable universe, including all of its matter and radiation, was compressed into a hot, dense mass just a few millimeters across.

Atmosphere, Biosphere, Hydrosphere, Lithosphere The area near the surface of the earth can be divided up into four inter-connected "geo-spheres:" the lithosphere, hydrosphere, biosphere, and atmosphere. Scientists can classify life and material on or near the surface of the earth to be in any of these four spheres. The names of the four spheres are derived from the Greek words for stone (litho), air (atmo), water (hydro), and life (bio). Lithosphere The lithosphere is the solid, rocky crust covering entire planet.

Fossil of ancient multicellular life sets evolutionary timeline back 60 million years A Virginia Tech geobiologist with collaborators from the Chinese Academy of Sciences have found evidence in the fossil record that complex multicellularity appeared in living things about 600 million years ago -- nearly 60 million years before skeletal animals appeared during a huge growth spurt of new life on Earth known as the Cambrian Explosion. The discovery published online Wednesday in the journal Nature contradicts several longstanding interpretations of multicellular fossils from at least 600 million years ago. "This opens up a new door for us to shine some light on the timing and evolutionary steps that were taken by multicellular organisms that would eventually go on to dominate the Earth in a very visible way," said Shuhai Xiao, a professor of geobiology in the Virginia Tech College of Science. The discovery sheds light on how and when solo cells began to cooperate with other cells to make a single, cohesive life form.

Space Sciences: Glossary Terms accretion - Process of growth or enlargement by gradual buildup. In the early solar system, dust and gas were pulled together by gravitational attraction to form planets, moons, and other objects airglow - Light seen in the upper reaches of the Earth’s atmosphere (in the layer called the ionosphere). When high-energy radiation from the Sun collides with molecules in the ionosphere, the molecules release energy in the form of light Timeline: The evolution of life By Michael Marshall There are all sorts of ways to reconstruct the history of life on Earth. Pinning down when specific events occurred is often tricky, though. For this, biologists depend mainly on dating the rocks in which fossils are found, and by looking at the “molecular clocks” in the DNA of living organisms. There are problems with each of these methods.

Earth’s Orbit Around The Sun Diagram of the Earths orbit around the Sun. Credit: NASA/H. Zell Ever since the 16th century when Nicolaus Copernicus demonstrated that the Earth revolved around in the Sun, scientists have worked tirelessly to understand the relationship in mathematical terms. If this bright celestial body – upon which depends the seasons, the diurnal cycle, and all life on Earth – does not revolve around us, then what exactly is the nature of our orbit around it? Commonly found fossils Belemnites 'If you find a bullet-shaped fossil you could well have found the remnants of an ancient squid. These fossils are called belemnites.' says our wildlife and countryside officer Pete Brash. The original creature was a ten-armed squid-like cephalopod related to the modern cuttlefish, and it lived in the seas up until 66 million years ago, dying out at the same time as the dinosaurs.

Moon Facts: Fun Information About the Earth’s Moon The moon is the easiest celestial object to find in the night sky — when it's there. Earth's only natural satellite hovers above us bright and round until it seemingly disappears for a few nights. The rhythm of the moon's phases has guided humanity for millennia — for instance, calendar months are roughly equal to the time it takes to go from one full moon to the next.

Australia's fossil past Australia, the world's oldest visible geology Ediacara fossils from the Flinders Ranges. Photograph courtesy of the Australian Heritage Council. A fossil is the impression of a living organism that has been preserved. Fossils are preserved in substances such as sediments, coal, tar, oil, amber, or frozen in ice. There are three main types of fossils: body, trace and chemical.

Solar System Exploration: : Planets Planets: The planet count in our solar system has gone as high as 15 before new discoveries prompted a fine tuning of the definition of a planet. The most recent change was in 2006 when scientists reclassified Pluto as a new kind of object - a dwarf planet. Fossils, Rocks, and Time: Fossil Succession If we begin at the present and examine older and older layers of rock, we will come to a level where no fossils of humans are present. If we continue backwards in time, we will successively come to levels where no fossils of flowering plants are present, no birds, no mammals, no reptiles, no four-footed vertebrates, no land plants, no fishes, no shells, and no animals. The three concepts are summarized in the general principle called the Law of Fossil Succession: The kinds of animals and plants found as fossils change through time. When we find the same kinds of fossils in rocks from different places, we know that the rocks are the same age. How do scientists explain the changes in life forms, which are obvious in the record of fossils in rocks?

Top 20 Worst Band Names Ever So this week's WQvote turned into quite a massive one, forcing us to expand the list in order to have the voice of UG community properly heard. Therefore, we're bringing you a Top 20. Apart from the bands listed below, you handsome devils condemned the whole "Verb the Noun" trend.