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 de ned 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.
In the rst person, write a narrative of about 200 words to describe the long journey from your last day on Earth to your fossil being discovered by humans millions of years later. Be creative in your writing!
11 Activity: Fossils
Exploring your backyard
Sedimentary rocks can reveal secrets from the past (like the shells above left) and create stunning scenery (like "The Wave" in northern Arizona, above right).
Time to choose! There are two tasks below and you may complete either one (or both!). The rst task is a hands-on activity, while the second you can complete from the comfort of your computer screen. Enjoy exploring the secrets of your backyard!
Experiment: Modelling how fossils form
Aim
To simulate the settling of sediments and the beginning of fossil formation.
Materials
2 L clear, plastic bottle with lid ¼ cup of mud ¼ cup of ne sand ¼ cup of coarse sand 10 small pebbles (less than 1 cm diameter) 10 small shells (less than 1 cm diameter) 1.5 L cold water
Hint: You may 褅nd a lot of these materials by searching in your own backyard!
12 Method
1. Add the mud, ne sand, coarse sand and pebbles to the plastic bottle so that the bottle is about one quarter lled. These components simulate sediment in an environment. 2. Add the shells to the bottle. These shells simulate organisms that may become fossilized. 3. Pour in cold water until the bottle is full. 4. Ensure the lid is tightly closed and then shake the bottle for several seconds. 5. Stop shaking the bottle and place immediately onto a table. 6. Use the project space below to describe what you observe occurring inside the bottle. You may like to include photographs, a short video clip or a labelled sketch in addition to a written description. 7. Repeat your observations, as in step 6, twice more in 10 minute intervals.
Results
Question 1
Record: Use this project space to record your observations in an organized way.
Discussion
Question 2
Sequence: List the components in the bottle into their settling order, beginning with the rst component to settle.
Question 3
Explain: Suggest an explanation for the sequence of settling you noted in Question 2.
13 Question 4
Locate: Identify where in the bottle's layers most of the "fossils" (shells) settled.
Question 5
Generalize: Review the conditions required for preservation of fossils that you have learned about in this lesson and predict whether you would expect the shells in the bottle to be preserved if this were a real world scenario. Give reasons for your response.
Research project: Dinosaurs in your backyard
Question 6
Research: Using the information you've gathered in this lesson, in addition to an internet search, complete the following tasks in the project space below.
1. Plot on a map of your local area, state, or country where dinosaurs have been found. 2. Annotate each map location with when the dinosaur lived (in millions of years ago, or Ma) and whether this was the Triassic, Jurassic or Cretaceous Era. 3. Choose one of the dinosaurs that lived in your area and:
Include a description and image of its appearance. Describe the environment that it lived in.
14 Career: Fossils
Sometimes Erika Canola feels like she works in a shbowl. Her lab at the Museum of Natural History in Los Angeles is surrounded by glass walls on all sides, allowing an audience to watch her every move.
The lab is part of the Dinosaur Institute, where the public gets to watch scientists prepare fossils with pneumatic tools – mini hammers and chisels that use compressed air to separate the ancient sediments that have moulded to the fossils.
At rst, Erika found it strange to be watched while she worked, but now it’s just a part of her everyday job as a paleontological preparator. Sometimes she’ll look up from her work and see kids making funny faces through the glass. Even celebrities come through to watch her work – one day she saw an actor from Jurassic Park staring right back at her!
When not in her “ shbowl”, Erika does eldwork and has travelled to places like Mexico and the Petri ed Forest in Arizona. Her favourite place for eldwork is Utah, with its red sandstone, pillowy clouds and stunning blue skies. At these dig-sites, she uses sledgehammers, jackhammers, and pneumatic tools to cut through the sandstone in the hope of nding new fossils. It’s hard work, she says, but it truly makes her feel like a treasure hunter.
Before her time at the Museum of Natural History Erika worked in professional hair and make-up. She was required to be creative and detail-oriented in that job, and she thinks the work has given her a unique perspective on working with fossils. But Erika soon found herself wanting more out of her career, and her love for bones, mystery and the outdoors switched her on to a degree in physical anthropology.
When she isn’t hunting for long-lost fossils, Erika enjoys tinkering with electronic gadgets, camping outdoors, and hanging out with her three dogs.
15 Question 1
Discover: There are a number of career opportunities available in the eld of palaeontology and archaeology. Perform an internet search to nd a career in one of these elds that interests you and describe what you would enjoy most about the job.
Hint: You may 밄nd this website to be a good starting point.
Image credits
Introduction: Bu etaut, Patrick Aventurier/Gamma-Rapho via Getty Images; A. huinculensis skeleton, Luka Barth/epa/Corbis; Gather: granite, James Driscoll; basalt, Thomas Weiland; buckled strata, iStock; Process: dinosaur skeleton, Javier Prieto Gallego/Cover/Getty Images; crinoids, iStock; dinosaurs illustration, Corey Ford/Stocktrek Images/Getty Images; dinosaur footprints,Tom Bean/Corbis; geological time scale, US Geological Survey; dragon y fossil, iStock; Activity: fossil shell and The Wave, iStock; Test: dinosaur print, Adobe Stock; geologic time scale, US Geological Survey; stegosaurus skeleton, Susannah Maidment et al. & Natural History Museum, London.
16 Test: Fossils
Note: There may be more than one correct answer to the multiple-choice questions below.
Question 1 (1 mark) Question 2 (1 mark)
What are the three main types of rock? Given the right conditions and enough time, rock of one type can turn into rock of another type. Igneous, sedimentary and metamorphic True Soft, hard and chalky False Granite, sandstone and schist I'm not sure I don't know
Question 3 (1 mark) Question 4 (1 mark)
A volcano erupts in Indonesia, producing a magni cent Granite is formed when magma cools very slowly deep lava ow. When the lava cools and solidi es it becomes: below the Earth's surface. It is therefore likely to have:
sediment no crystals
sedimentary rock small crystals
metamorphic rock large crystals
igneous rock I'm not sure
I'm not sure
17 Question 5 (1 mark) Question 6 (1 mark)
Sedimentary rocks are formed: Marble is formed when limestone is subjected to intense heat and pressure deep below the surface. This means from the cemented remains of weathered and that marble is a type of: eroded rocks sedimentary rock deep in the earth's crust from molten rock igneous rock when molten rock erupts at the surface metamorphic rock when older rocks are altered by heat and pressure I'm not sure I'm not sure
Question 7 (1 mark) Question 8 (1 mark)
Earth scientists who study fossils and ancient life are Fossils are: called: the remains of ancient plants and animals speleologists usually found in sedimentary rocks meteorologists always preserved bones palaeontologists any traces left by living things, like the microbiologists pawprints my dog left at the beach yesterday
I'm not sure I'm not sure
Question 9 (1 mark) Question 10 (1 mark)
Fossils are important because they provide evidence of the A sea creature dies and is buried in mud. Its body is diversity of life and how it has changed through Earth's eventually destroyed but the mud surrounding it hardens history. and preserves its shape. The resulting fossil is called a:
True trace fossil
False body fossil
I'm not sure mold fossil
resin fossil
I'm not sure
Question 11 (1 mark) Question 12 (1 mark)
When preserved, which of the following are trace fossils? Which of the following animals is most likely to be preserved as a resin fossil? Bite marks Sabre-toothed tiger Tracks and footprints Tyrannosaurus rex Bones Mosquito Animal droppings Koala I'm not sure I'm not sure
18 Question 13 (1 mark)
The photo on the left shows a well-preserved dinosaur footprint. In which of the following time periods is it most likely to have formed?
Stone Age, 3.4 million – 2000 years ago
Mesozoic Era, Jurassic Period: 200 – 145 million years ago
Early Archean Era, 4000 – 3200 million years ago
I'm not sure
Question 14 (1 mark)
A dinosaur died in China 75 million years ago and was buried by sediment.
During which epoch in Earth's history did this event occur?
Early Devonian
Pliocene
Late Jurassic
Late Cretaceous
I'm not sure
19 Question 15 (1 mark)
The skeleton on the left belongs to a stegosaurus, a large plant-eating dinosaur that lived in North America about 150 to 156 million years (Ma) ago.
According to the geological time scale, the stegosaurus lived in the:
Mesozoic Era, Jurassic Period, Late Jurassic Epoch
Cenozoic Era, Tertiary Period, Paleocene Epoch
Paleozoic Era, Silurian Period, Early Silurian Epoch
Mesozoic Era, Triassic Period, Late Triassic Epoch
I'm not sure
Question 16 (1 mark)
The boundary between the Late Cretaceous and Early Paleocene Epochs (65.5 Ma) is thought to mark a mass extinction event that caused the demise of the dinosaurs along with about three quarters of all land and marine species.
Which piece of fossil evidence would be inconsistent with this conclusion?
About three-quarters of all species preserved as fossils below the boundary are absent in rocks above the boundary
A dinosaur fossil thought to belong to the Eocene Epoch
Diverse dinosaur fossils found in rocks of Cretaceous age
Diverse mammal fossils in Tertiary rocks, in habitats previously dominated by dinosaurs
I'm not sure
Question 17 (1 mark)
Learning goal 1: List the three main types of rock and explain brie y how they are formed.
Question 18 (1 mark)
Learning goal 2: A Tyrannosaurus rex died in a swamp 66 million years ago. Describe the steps that must have followed in order to preserve its skeleton as a fossil.
20 Question 19 (1 mark)
Learning goal 3: Explain why you would expect to nd very di erent fossils in rocks of Pleistocene age compared to those of Jurassic age.
Total available marks: 19
21