BBC Nature - History of life on Earth The Universe This picture shows the overall structure of our universe. This is just a small piece, but it is enough to see that matter is organized in strands, or strings. Lets start from the beginning. The Earth revolves around the Sun. The Sun in turn revolves or circles the center of the galaxy. Our galaxy is part of a group of galaxies called the Local Group. Now here is where it gets fun. Millions of galaxy clusters around the universe are strung together like a spiderweb. If you could look at the entire universe at once it would look like a giant spiderweb, made up of billions of galaxies, and trillions and trillions of stars.
Fossil of ancient multicellular life sets evolutionary timeline back 60 million years -- ScienceDaily 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.
History of Earth Artistic concept of the primordial Earth when it was much hotter and hostile to life The history of Earth concerns the development of the planet Earth from its formation to the present day.[1][2] Nearly all branches of natural science have contributed to the understanding of the main events of the Earth's past. The age of Earth is approximately one-third of the age of the universe. An immense amount of biological and geological change has occurred in that time span. The first life forms appeared between 3.8 and 3.5 billion years ago. Geological change has been constantly occurring on Earth since the time of its formation and biological change since the first appearance of life. Earth's history with lengths of the eons to scale Geologic time scale[edit] The history of the Earth is organized chronologically in a table known as the geologic time scale, which is split into intervals based on stratigraphic analysis.[2][9] A full-time scale can be found at the main article. Millions of Years
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. Modern genetics allows scientists to measure how different species are from each other at a molecular level, and thus to estimate how much time has passed since a single lineage split into different species. These difficulties mean that the dates in the timeline should be taken as approximate. 3.8 billion years ago? This is our current “best guess” for the beginning of life on Earth. At some point far back in time, a common ancestor gave rise to two main groups of life: bacteria and archaea. How this happened, when, and in what order the different groups split, is still uncertain. 3.5 billion years ago 3.46 billion years ago
How Was The Earth Created? Hello Earth - Origins of Our Planet Where did the Earth come from? This is an important question. A question that helps us understand our own origin as a race of sentient, thinking beings. Did the Earth always exist? These are difficult questions to answer. Commonly found fossils | National Trust 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. Ammonites 'Ammonites look a lot like coiled snail shells, but they were actually sea predators,' says our expert Rod Hebden. The ammonite was a tentacled sea creature that lived between 400 and 66 million years ago, similar to today's nautilus but more closely related to octopuses and squid. Ammonite fossils can be found in Dorset, and you can see two polished ammonites at Arlington Court, in Devon. Devil’s Toenails (Gryphaea) Although these commonly found fossils look like the claw of an ancient animal or, indeed, a devil, they were created from oysters that once lived on shallow sea beds. They are between 200 and 66 million years old, relics of a time when what is now the land in Britain was covered by the sea, and are particularly common on the coast of Yorkshire. Sea sponges and sea urchins
Charles Darwin & Evolution ‘Probably all the organic beings which have ever lived on this earth have descended from some primordial form, into which life was first breathed’ This is all Darwin says in The Origin of Species about the origin of life. When the public is asked about what problems they think face evolutionary theory one subject that comes up quite often is the origin of life. Evolution, they say, does not explain how life began, therefore there must be something wrong with evolution. When people say this they are partly correct: evolution does not explain how life began. Some Warm Little Pond Secretly, Darwin did have his own ideas about how life kicked off; he thought that life probably began spontaneously from the chemical soup that existed as the earth began to calm down a bit following its violent birth. ‘But if (and Oh! Darwin had actually hit the nail on the head, the origin of life is a problem for chemistry and biochemists. In 1953 two people created Darwin’s warm little pond. Get your coat
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. As well as body fossils, which are actual skeletal remains, there are impressions of soft animals, plants and footprints which have been left as mud hardened. Large numbers of fossils indicate that an enormous number of plants and animals have lived on Earth since life evolved more than 3,500 million years ago. Because of its relative isolation over millennia, Australia has a rich, unique fossil record, dating from approximately 3.2 billion years ago, close to when the Earth was stabilising its formation. Fossil sites Riversleigh, north-west Queensland, one of the most important fossil sites in the world. Australia has the world's best example of dinosaur tracks. Palaeontologists
GCSE Bitesize: The origins of the universe 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? Scientific theories are continually being corrected and improved, because theory must always account for known facts and observations. The study of fossils and the rocks that contain them occurs both out of doors and in the laboratory.
Evolution and the Fossil Record by John Pojeta, Jr. and Dale A. Springer Dating the Fossil Record (Previous Page || Next Page) The study of the sequence of occurrence of fossils in rocks, biostratigraphy, reveals the relative time order in which organisms lived. Although this relative time scale indicates that one layer of rock is younger or older than another, it does not pinpoint the age of a fossil or rock in years. Determining the age of a rock involves using minerals that contain naturally-occurring radioactive elements and measuring the amount of change or decay in those elements to calculate approximately how many years ago the rock formed. About 90 chemical elements occur naturally in the Earth. To help in the identification and classification of elements, scientists have assigned an atomic number to each kind of atom. Although all atoms of a given element contain the same number of protons, they do not contain the same number of neutrons. Potassium (atomic number 19) has several isotopes. (Previous Page || Next Page)