The continental configuration when the Ordovician began was like the Cambrian’s, with . The began . The that would impress modern observers were formed in the Ordovician. Different animals built the corals (, , ) than Cambrian reef builders; but there were no schools of fish swimming around them, as the Ordovician predated the rise of fish. Fish existed (, , ), but they were armored, , and lived on the seafloor. The may have appeared in the Ordovician, but because they had cartilaginous skeletons, the fossil record is equivocal. Some fish had scales, and an eel-like fish might have even had . Teeth and claws were early energy technologies; energy applied by muscles could be concentrated to hard points or plates that could crush or penetrate other organisms or manipulate the environment.
The journey of life on Earth has been greatly affected by geophysical and geochemical processes as well as influences from beyond Earth, such as:
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The culture (x. 22 kya to 17 kya) succeeded the Gravettian culture, to in its turn be succeeded by culture (c. 17 kya to 12 kya), and (also called ) appeared. Those cultures were in France and Spain, the Neanderthals’ former range, in the refugia from the ice sheets that blanketed northern Europe, and the Magdalenian culture spread northward as the current interglacial interval began.
First large-scale energy users.
Dinosaurs begin to dominate, and mammals first appear several million years later. first appear. Some argue that this extinction is more significant than the end-Triassic extinction.
First complex ecosystems appear.
Closure of gap between Atlantic and Pacific Oceans between the Americas, and resultant Gulf Stream dynamics which may have initiated current ice age.
Concentrated application of muscle energy.
As will become a familiar theme in this essay, the rise and fall of species and ecosystems is always primarily an energy issue. The Ediacaran extinction is a good example: Ediacaran fauna either an energy source for early Cambrian predators, ran out of food energy, ran out of the oxygen necessary to power their metabolisms, or lacked some other energy-delivered nutrient. After the extinction events, biomes were often cleared for new species to dominate, which were often descended from species that were marginal ecosystem members before the extinction event. They then enjoyed a of relative energy abundance as their competitors were removed via the extinction event.
The most complex aquatic ecosystem appears.
In his , Charles Darwin sketched processes by which species appear and disappear, today called speciation and extinction. is a landmark in scientific history and is still immensely influential. But it was also afflicted by false notions that are still with us. Europe’s emergence from dogma and superstition has been a long, fitful, only partially successful process. In the 1500s, Spanish mercenaries to the unfortunate Indians that they conquered and annihilated that stated that Creation was about five thousand years old, as scholars of the time simply added up the “begats.” The is filled with tales of genocide, miracles, and disasters, with a global flood that the faithful survived. As geology gradually became a science and processes such as erosion and sedimentation were studied, the Judeo-Christian belief of Earth's being five thousand years old and the concept of arose in Europe.