one great landmass. Scientists call this super-continent Pangaea, which means “All Earth”. The first dinosaurs lived in the early Triassic. Other reptiles also lived in this period, such as plant-eating rhynchosaurs. Fish and turtles swam in the sea, pterosaurs flapped their leathery wings in the sky, and the first mammals appeared. Pangaea split into northern and southern landmasses in the Jurassic Period, divided by the ocean. In time, the two new continents moved apart. Dinosaurs colonized the land, from huge plant-eating species to smaller meat-eating ones. Pterosaurs ruled the sky, the first birds appeared, and ichthyosaurs and horseshoe crabs swam in the seas. Fierce predatory dinosaurs hunted and scavenged for meat. Plant-eating dinosaurs grew body armour for protection. Crocodiles, turtles, and lizards flourished, and the first snakes appeared. Insects, birds, and pterosaurs flew in the sky, and small mammals ran on the ground. 11. Why is the Cenozoic also known as the Age of Mammals? (2) The Cenozoic is also known as the Age of Mammals , because the largest land animals have been mammals during that time. The extinction of many large diapsid groups such as non-avian dinosaurs, Plesiosauria and Pterosauria allowed the mammals and birds to greatly diversify and be the predominant fauna, even to the present day. 12. How do index fossils provide evidence of a change in climate in a particular area? (2) Fossils are preserved impressions in rock that tell us when, where, and how living organisms lived and behaved millions of years ago. The word fossil means ‘dug out of the ground’. The majority of fossils are found in exposed sedimentary rock. The most common types of fossil rocks are limestone, sandstone and shale. Paleontologists are scientists who study early life forms by interpreting plant and animal fossils. After carefully removing the fossils from the rock they are studied and interpreted. Most fossils are fragments or parts of skeletons, shells or other animal traces. The inferences made suggest that life on Earth has changed a great deal over the past million of years. Fossils found in younger rocks are much like the organisms living today. Older rocks contain fossils of organisms that are extinct (no longer existing). The trilobite, that lived on the ocean floor over 300 million years ago, is an example of an extinct organism, that we have only seen as a fossil. The fossil record in rocks indicates a sequence of different life forms appearing at different times. Single celled life forms appeared before multi-celled life forms, plants before animals, and invertebrates before vertebrates. Older rocks show more diversity than there is today. The ability to reconstruct fossils based on knowledge of current living things is an important part of understanding the history of our planet. With only fragments and pieces, scientists must try to fill in the missing gaps - through inferences and educated guesses.
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