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This refers to the fact that fossils are the remains of past life preserved in rock, soil or amber. Generally, the remains were once the hard parts of an organism, such as bones and shell although, under exceptional dating dinosaur fossils, soft tissues have also fossilised. There are different types of fossils because remains can be preserved in a variety of ways. Examples of trace fossils that have been found include:. Animal and plant remains can undergo a variety of physical and chemical changes during fossilisation.
When paleontologist Mary Schweitzer found soft tissue in a Tyrannosaurus rex fossilher discovery raised an obvious question -- how the tissue could have survived so long? The bone was 68 million years old, and conventional wisdom about fossilization is that all soft tissue, from blood to brainsdecomposes. Only hard parts, like bones and teeth, can become fossils. But for some people, the discovery raised a different question. How dating dinosaur fossils scientists know the bones are really 68 million years old? Today's knowledge of fossil ages comes primarily from radiometric datingalso known as radioactive dating. Radiometric dating relies on the properties of isotopes. These are chemical elements, like carbon or uranium, that are identical except for one key feature -- the number of neutrons in their nucleus.
Age bias continually colors the interpretation of dinosaur fossils. How do we know secular analyses are flawed? Is there evidence that confirms dinosaurs lived recently? Full-Bible Christian. Why Does Recent Creation Matter?
More about dating dinosaur fossils:
The Age of Dinosaurs was so many millions of years ago that it is very difficult to date exactly. Scientists use two kinds of dating techniques to work out the age of rocks and fossils. The first method is called relative dating. This considers the positions of the different rocks in sequence in relation to each other and the different types of fossil that are found in them. Dating dinosaur fossils second method is called absolute dating and is done by analysing the amount of radioactive decay in the minerals of the rocks. Scientists find out the age of a dinosaur fossil by dating not only the rocks in which it lies, but those below and above it. Sometimes, scientists already know the age of the fossil because fossils of the same species have been found elsewhere and it has been possible to establish accurately from those when the dinosaur lived. Geologists call this the principle of lateral continuity. A fossil will always be younger than fossils in the beds beneath it and this is called the principle of superposition. In an undisturbed sequence of rocks, such as in a cliff face, it is easy to get a rough idea of the ages of the individual strata — the oldest lies at the bottom and the youngest lies at the top.
The most widely known form of radiometric dating is carbon dating. This is what archaeologists use to determine the age of human-made artifacts. But carbon dating won't work on dinosaur bones. The half-life of carbon is only 5, years, so carbon dating is only effective on samples that are less than 50, years old. Dinosaur bones, on the other hand, are millions of years old -- some fossils are billions of years old. To determine the ages of these specimens, scientists need an isotope with a very long half-life. Some of the isotopes used for this purpose are uranium, uranium and potassiumeach of which dating dinosaur fossils a half-life of more than a million years. Unfortunately, these elements don't exist in dinosaur fossils themselves.
This helps us to understand how that species fits into the evolutionary tree of change; when did they first appear and when did the last of their kind walk this Earth? Radiometric dating involves exploiting the radioactive decay of unstable atoms naturally present in the structure of bones and rocks. In old dinosaur bones, the material is buried under layers upon layers of sediment under high pressure. This means that it is almost impossible for isotopes to enter or leave the premises. By comparing the ratio of unstable isotopes vs. When dating a specimen, there are many different isotopes that can be tracked. Now, this technique is pretty cool if you want to calculate the age of a tree, for example, or even an Ancient Egyptian king a few thousand years young.