Assessment: Fossils

Subject: Science | Year: 6

Name: _________________________ Class/Set: ____________ Date: ____________

Section A: Knowledge Check (Multiple Choice)

Mark the correct answer.

⇨ The data provided in the table below shows the depth at which various fossilised remains were discovered during a recent palaeontological dig in Dorset.

Fossil Type	Depth Found (Metres)	Estimated Age (Millions of Years)
Mammal Jaw	2m	10
Ammonite	15m	150
Belemnite	12m	135
Trilobite	45m	500

Q1: Based on the table and the Law of Superposition, which of these fossils is the oldest? a) ☐ Mammal Jaw b) ☐ Ammonite c) ☐ Belemnite d) ☐ Trilobite

Q2: In which type of rock are these fossils most likely to have been discovered? a) ☐ Igneous rock formed from cooled lava. b) ☐ Sedimentary rock formed from layers of silt and sand. c) ☐ Metamorphic rock formed by intense heat and pressure. d) ☐ Volcanic glass formed by rapid cooling.

Q3: What is the specific term for the process where minerals from groundwater seep into the remains of an organism and turn it into stone? a) ☐ Evaporation b) ☐ Solidification c) ☐ Permineralisation d) ☐ Condensation

Q4: If a scientist finds a fossilised footprint rather than a bone, what type of fossil have they discovered? a) ☐ A cast fossil. b) ☐ A mould fossil. c) ☐ A trace fossil. d) ☐ A resin fossil.

Q5: Why is the fossil record considered "incomplete" by scientists? a) ☐ All animals that have ever lived turned into fossils. b) ☐ Soft-bodied organisms rarely fossilise and many rocks are destroyed by the rock cycle. c) ☐ Fossils only form in the ocean, never on land. d) ☐ Humans have already found every fossil that exists.

Section B: Application (Written Answers)

Answer in the spaces provided.

⇨ The following extract describes the discovery of a prehistoric fish fossil found in a mountainous region of the Himalayas.

Scientists recently discovered the fossilised remains of a saltwater 'Bluefin' fish high up in the Himalayan mountains. The fossil is exceptionally well-preserved, showing the intricate structure of the scales and fins. However, no evidence of the fish's internal organs or muscles remains. The surrounding rock is limestone, which usually forms at the bottom of warm, shallow seas.

Q6: Explain why the scales and fins of the fish were preserved as fossils, but the internal organs and muscles were not. [3 marks]

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Q7: Based on the evidence in the extract, explain how it is possible for a saltwater fish fossil to be found at the top of a mountain range. [5 marks]

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Total Marks: _______ / 13

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⚠ TEACHER’S GUIDANCE

💡 Pedagogical Pulse

• Identify: Students often struggle with the concept of deep time. Use the table in Section A to reinforce that deeper layers generally equate to older time periods (Superposition).
• Clarify: Ensure students understand that fossils are not the original bone, but a mineral replacement (rock).
• Model: For Section B, encourage students to use 'PEEL' (Point, Evidence, Explanation, Link) or 'Because, But, So' to structure their scientific reasoning.
• Misconception Alert: Watch for students who believe fossils are found in volcanic rock; explain that the heat would destroy the organic matter.

Section A Answers

Q1: d

Explanation: The Trilobite is found at the greatest depth (45m), which, according to the Law of Superposition, indicates it is the oldest layer.

Q2: b

Explanation: Sedimentary rock is formed by the gradual accumulation of particles, which allows for the burial and preservation of organic remains without the destructive heat of igneous or metamorphic processes.

Q3: c

Explanation: Permineralisation is the specific scientific term for mineral-rich water filling the pores of organic tissues.

Q4: c

Explanation: Trace fossils provide evidence of the activities of organisms (footprints, burrows, coprolites) rather than the organism itself.

Q5: b

Explanation: Most organisms decompose completely. Soft tissues rarely survive the fossilisation process, and geological activity often destroys sedimentary layers.

Section B Guidance

Q6 Guidance

• 1 Mark: Identification that hard parts (scales/fins/bones) are more durable.
• 1 Mark: Explanation that soft tissues (organs/muscles) decay or are eaten by scavengers before fossilisation can occur.
• 1 Mark: Mention of the time required for minerals to replace the tissue.

Model Answer: "The scales and fins were preserved because they are the 'hard parts' of the fish, which are more resistant to decay. In contrast, the internal organs and muscles are soft tissues that usually rot away or are consumed by scavengers very quickly after death, before they have the chance to be buried by sediment and fossilised."

Q7 Guidance

• 1 Mark: Recognition that the environment has changed over millions of years.
• 1 Mark: Identifying that the area was once under a shallow sea (as evidenced by the limestone).
• 1 Mark: Explaining tectonic plate movement.
• 1 Mark: Explaining the process of 'uplift' (plates colliding).
• 1 Mark: Linking the fish's presence to the sea floor being pushed upwards to form mountains.

Model Answer: "The discovery of a saltwater fish in the Himalayas provides evidence that the land was once at the bottom of a shallow sea millions of years ago. Over vast periods of time, the Earth’s tectonic plates collided. This caused the sea floor to be pushed upwards in a process called uplift, eventually forming the mountain range. The fish was trapped in the seafloor sediment (limestone) and was carried upwards as the mountains grew."