Dinosaur fossils can found rocks dating

18 Sep

Throughout the history of life, different organisms have appeared, flourished and become extinct.Many of these organisms have left their remains as fossils in sedimentary rocks.Early geologists, in the 1700s and 1800s, noticed how fossils seemed to occur in sequences: certain assemblages of fossils were always found below other assemblages. Since 1859, paleontologists, or fossil experts, have searched the world for fossils.In the past 150 years they have not found any fossils that Darwin would not have expected.Other critics, perhaps more familiar with the data, question certain aspects of the quality of the fossil record and of its dating.These skeptics do not provide scientific evidence for their views.This law of science tells us that dirt, mud, sand and other sediments are almost always deposited in horizontal layers.As these sediments stack up vertically, they often harden, forming rock layers.

But how do we know this evolutionary sequence of layers, one on top of the other, is accurate? Two laws, or principles of geology explain why rock layers are formed in this way.Relative dating does not provide actual numerical dates for the rocks.Fossils are important for working out the relative ages of sedimentary rocks.Unlike people, you can’t really guess the age of a rock from looking at it.Yet, you’ve heard the news: Earth is 4.6 billion years old. That corn cob found in an ancient Native American fire pit is 1,000 years old. Geologic age dating—assigning an age to materials—is an entire discipline of its own.Our understanding of the shape and pattern of the history of life depends on the accuracy of fossils and dating methods.Some critics, particularly religious fundamentalists, argue that neither fossils nor dating can be trusted, and that their interpretations are better.Some fossils, called index fossils, are particularly useful in correlating rocks.For a fossil to be a good index fossil, it needs to have lived during one specific time period, be easy to identify and have been abundant and found in many places. If you find ammonites in a rock in the South Island and also in a rock in the North Island, you can say that both rocks are Mesozoic.Current understanding of the history of life is probably close to the truth because it is based on repeated and careful testing and consideration of data.The rejection of the validity of fossils and of dating by religious fundamentalists creates a problem for them: Fossil sequences were recognized and established in their broad outlines long before Charles Darwin had even thought of evolution.