Earth and space sciences Fossils Earth scientists use rocks and fossils to obtain clues about the environment that existed many millions of years ago. Just recently, some scientists made a discovery about a four-winged, feathered dino-bird! This is a print version of an interactive online lesson. To sign up for the real thing or for curriculum details about the lesson go to www.cosmoslessons.com Introduction: Fossils The closest living relation to the dinosaurs could be your budgerigar! We’ve long known that birds evolved from dinosaurs. But a newly discovered fossil of a feathered 횆ying dinosaur in a remote part of China gives us fresh evidence about how dinosaurs and early birds took to the skies. The dinosaur is called Changyuraptor yangi. It was the size of a large eagle, weighing roughly 4 kilograms and measuring about 1.3 metres from snout to tail. And it had not two, but four wings and a long plumed tail. So well preserved were the feathers of the 횆ying dinosaur's tail that scientists could work out how it was used in 횆ight. They believe that it allowed the dinosaurs to adjust their pitch – that is, whether they were 횆ying nose up or nose down – as well as to slow their speed and help them land safely. The discovery adds to the growing body of evidence that the late Jurassic and early Cretaceous periods were important for the evolution of feathered 횆ight. As one scientist says, “There were lots of diꏶerent lineages experimenting with modes of 횆ight at this time. The lineage that became modern birds was just one of them.” Read the full Cosmos Magazine article here. Left: Archaeologists use delicate tools to uncover long-buried fossils. Here, archaeologist Eric Buꏶetaut can be seen excavating the neck of a Sauropoda dinosaur. Right: The skeleton of an Argentinosaurus huinculensis, the world's largest herbivore, is displayed at the Lokschuppen exhibition centre in Rosenheim, Germany. Question 1 Imagine: You are a palaeontologist working at a university and have been contacted by a farmer who has stumbled across a strange looking fossil. Describe how you might feel if you visited the farmer and then spent one month digging up one of the largest dinosaurs ever found: Argentinosaurus, 36 m from tail tip to nose. 1 Gather: Fossils Rock types 0:00 / 3:45 Credit: Rock Types and the Rock Cycle: Igneous, Sedimentary, Metamorphic by Untamed Science (YouTube). 2 Question 1 Notes: Use this space to take notes for the video. Note: This is not a question and is optional, but we recommend taking notes – they will help you remember the main points of the video and also help if you need to come back to answer a question or review the lesson. Question 2 Remember: What are the three main types of rock? Question 3 Classify: Igneous rocks are composed of di‰erent minerals that form as magma (molten rock) cools and solidi㔴es. The slower the magma cools, the larger the crystals formed. Which of the two igneous rocks below is a granite (that cools deep in the Earth very slowly) and which is a basalt (that cools very quickly when the magma reaches the surface of the Earth)? Give a reason for your answer. Two types of igneous rock. 3 Question 4 Question 5 Identify: Where are sediments deposited? Recall: The sediments that form sedimentary rocks can be eroded from other sedimentary rocks, igneous rocks Sea 㘸oors and/or metamorphic rocks. Deep within the crust True Rivers False Lakes I'm not sure In the atmosphere I'm not sure Question 6 Identify: Which class of rock is represented by the photograph on the right and how do you know this? Hint: What has caused the layers in the rock to be deformed? 4 The rock cycle The rock cycle is the set of processes that convert rocks of one type into another type, or convert rock into sediment and back into rock again. As we saw from the video there are three main classes of rock: sedimentary, metamorphic, and igneous, and the di‰erences between them have to do with how they are formed. Rocks are not always as static and solid as they appear. They are constantly changing over timescales from: a few minutes, for example when lava 㘸ows out of a volcano in Hawaii, to many millions of years, for example as the Himalayan mountains are uplifted and folded. To start the rock cycle, hot molten rock from the Earth's mantle, also called magma, reaches the surface of the Earth and erupts from volcanoes as lava. The lava cools and forms igneous rocks. Weathering by wind, ice and rain results in the rocks being eroded, broken up and transported along rivers and streams into the ocean. The particles of sand, shells and pebbles, which are collectively called sediment, slowly build up over hundreds of thousands to millions of years. They are compressed, and sedimentary rocks form. Sedimentary rock is the most common type of rock exposed on the Earth's surface. As more and more sediment accumulates, increased pressure and temperature lead to deep sedimentary rocks slowly transforming into metamorphic rocks. Over millions of years the temperature of the Earth may melt some metamorphic rocks back into magma. And so the process continues... Question 7 Identify: Use Google Earth to locate an area that is local to your school where sediment being deposited may form sedimentary rock in the future. Upload a snapshot of the area. Annotate where the sediment is being eroded from. (Hint: The canvas tool can be used to annotate images.) Describe how the sediment is being transported to the depositional area. 5 Process: Fossils Left: Dinosaur in the Jurassic Museum of Asturias, Spain. Right: Fossil crinoids (Uintacrinus socialis) from the Cretaceous Period (145 – 65.5 million years ago). Fossils Simple cells represent the earliest life forms on Earth. They rst appeared approximately 3.6 billion years ago. More complex life forms evolved only approximately 600 million years ago. When these ancient plants and animals died their remains were sometimes preserved as fossils in sedimentary rock. Fossils are much more common than you may think since so many animals and plants live and die and because sedimentary rocks are so common. Dinosaurs are arguably the most fascinating and well-known fossils. Flying dinosaurs such as Changyuraptor and Archaeopteryx represent transition animals that existed between dinosaurs and birds. Earth scientists and geologists who study fossils and ancient life are known as palaeontologists. 6 0:00 / 2:39 Credit: How Fossils Are Formed by SheppardSoftwareCom (YouTube). Question 1 Notes: Use this space to take notes for the video. Note: This is not a question and is optional. Question 2 Classify: Which type of animal might have left the trace fossil tracks shown below right? On paper, draw a sketch of what the animal may have looked like and upload a photograph or scan of your sketch. Hint: The animal that left these tracks may have been being swooped by an Archaeopteryx, depicted soaring overhead (below left). 7 Question 3 Think: How are resin fossils formed? List three animals that might become resin fossils. Question 4 Paraphrase: On very rare occasions exceptionally well-preserved body fossils have been discovered. Use the information in the video clip above to explain how dinosaur body fossils can be preserved in rock. 8 The geological time scale Earth scientists and geologists use the geological time scale to measure time over Earth's history since its formation about 4.6 billion years ago. As shown on the right, geological time is divided into eons, eras, periods and epochs. The boundaries between these divisions are dened by characteristic rock types and fossils. Geological time is measured in millions of years, abbreviated Ma. Today we are living in the Holocene Epoch of the Quaternary Period. The newly discovered fossil of the feathered dinosaur Changyuraptor yangi, described in the Introduction, is 125 million years old. This places it within the Early Cretaceous Epoch, the Cretaceous Period, the Mesozoic Era and the Phanerozoic Eon. Note: The Pennsylvanian and Mississippian Periods are terms used in the United States to refer to the Carboniferous Period. Question 5 Question 6 Evaluate: Early Cretaceous rocks are older than Late Compare: Which of the following geological time periods Triassic rocks. lasted the longest? True Cenozoic Era False Cretaceous Period I'm not sure Oligocene Epoch Paleozoic Era I'm not sure 9 Question 7 Question 8 Classify: A fossil is dated as being 370 million years old. Interpret: The Mesozoic Era is cometimes called the Age Which epoch does it belong to? of Reptiles because of the dominance of the dinosaurs. This era lasted from: Late Cambrian 65.5 to 2.4 Ma Late Devonian 200 to 65.5 Ma Middle Permian 251 to 65.5 Ma Early Jurassic 542 to 251 Ma I'm not sure I'm not sure Question 9 Apply: Suppose the sedimentary rock containing this insect fossil has been dated to 282 Ma. Using the geological time scale above, identify the epoch, period and era to which it belongs. Question 10 Calculate: The Cosmos Magazine article suggests that ying dinosaurs rst appeared at the beginning of the Late Jurassic, and were extinct by the end of the Early Cretaceous. 1. Calculate how many millions of years the ying dinosaurs dotted the skies of the Earth. 2. Calculate the percentage of time in Earth's history this represents based on the Earth being 4.6 billion years old. Give your answer to one decimal place. 10 Question 11 Imagine: You're an old ying dinosaur from the Late Jurassic and feel that your death is imminent! But you're a smart dinosaur who knows about fossilization and you want to make sure that your body is preserved for future discovery by humans.