During the Cenozoic Era the global climate has turned colder, with the ice caps returning to North America, Eurasia, and Antarctica. All continents extensively developed rocks, particularly on lowland plains such as the Gulf and Atlantic coastal plains of North America. This time in Earth's history marks the disappearance of the dinosaurs.
What is true about life on Earth at this time?
Answers
Answer: The origin of life is one of the great mysteries in the Universe. To determine the origin of life, scientists are investigating the problem in several different ways. Some scientists are studying life on our own planet. Some scientists are seeking out life or fossil life on other planets or moons in our solar system. And other scientists are trying to detect life in other solar systems, either by measuring life's effects on the atmospheres of distant planets or by measuring artificial radiation like radio signals that may be produced by advanced life.
Thus far, the most fruitful approach has been to examine life on our own planet. However, even in our own backyard, it is difficult to determine life's origins because it began at least 3.5 billion years ago. We know that life began at least 3.5 billion years ago, because that is the age of the oldest rocks with fossil evidence of life on earth. These rocks are rare because subsequent geologic processes have reshaped the surface of our planet, often destroying older rocks while making new ones. Nonetheless, 3.5 billion year old rocks with fossils can be found in Africa and Australia. They are usually a mix of solidified volcanic lavas and sedimentary cherts. The fossils occur in sedimentary cherts.