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Vertebrates History in Rocks (Interpretation of Fossils (Paleontologists…
Vertebrates History in Rocks
Millions of years ago, in an ancient pond, some fishes died and their bodies were settled into the mud on the bottom and soon heavy rains fell lots of mud washed into the pond covering the fishes. The soft tissues of the fish has decayed, but their bones remained and after many thousands of years, the mud hardened into rock, the bones became the fossils.
What are Fossils
A fossil is the hardened remains or other evidence of a living thing that existed a long time ago and sometimes a fossil is an imprint in a rock like an animal's footprint or the outline of a leaf.
Are there fossils are the remains of skeletons, shells, bones, or other parts of living things and fossils are made when a chemical process takes place over time during which an organism whose tissues are replaced by hard minerals.
Most living tissues decay rapidly and only a very few organisms are preserved as fossils.
Fossils are found most frequently in sedimentary rock and Harden layers of sediments make up sedimentary rock.
Sediment contain particles of clay, mud, silt, or sand.
Sediments build up in layers in many ways and for example wind can blow a thick layer of sand ontom dunes
Sediments can also form when muddy water stands in an area for a long time and muddy sediment in the water eventually settles to the bottom building up.
Over a long long time layers of sediment can be pressed and cemented together to form rock and as sedimentary rock forms are traces of living things that have been trapped in the sediments are sometimes preserved as fossils.
Interpretation of Fossils
Paleontologists the scientists who study extinct organisms examine fossil structures making comparisons to present-day organisms and by studying fossils paleontologists can infer how animals changed over time.
An important piece of information that paleontologists can learn from a faucet is it approximately age.
A Fossils Age
A method for estimating a fossils age takes advantage of the process in which sediments form Instinct about sediment settling out of water, the lowest layers are deposited first, newer sediments settle on top of the older layers.
Fossils in higher layers of rock are often younger than the fossils in lower layers and rock layers can become tilted or even turned upside down by events like earthquakes.
A fossils position in rock is not always a good indication of its cage because scientists usually rely on other methods to help determine a fossils age.
For example, fossils and the rocks in which they are found contain some radioactive chemical elements and radioactive elements Decay, or change into other chemical elements over a known period of time.
The more there is of decayed form of the element the older the fossil is.
Using Fossils
Paleontologist use fossils to determine likely pattern of how vertebrates changed over time.
Patterns of vertebrate Evolution looks something like a branching tree and fossils show that the first vertebrates to live on earth were fishes.
Fishes first appeared on Earth about 530 million years ago and in phibians which appeared on Earth 380 million years ago are descended from fishes. Then about 320 million years ago amphibians gave rise to reptiles and both birds and mammals are descended from reptiles.
According to the information on the age of the oldest mammal fossils mammals first lived on earth about 220 years ago and birds were the latest group of vertebrates to arise. The oldest fossils show that Birds first appeared on Earth 150 million years ago.