Worksheet

Six Legs Through Time: The Insect Club's Fossil Case

Grade 8 fossil record practice: an insect club reads first and last appearances and a graph of insect orders to find patterns of origin, extinction and recovery.

Grade 8ScienceInteractive · Printable

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1 NGSS standard
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11 questions
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Format: Interactive · Printable
Grade: Grade 8
Subject: Science
Question types: Fill in the blank, Multiple choice, Circle the answer, Short answer

About this worksheet

What students practice

Students use first and last fossil appearances to describe when insect groups appeared and died out.
Students read a graph of insect orders to find a sharp loss and a later rise in diversity.
Students use fossil data to argue that insect life has changed over Earth's history.

How to use

Read the passage together and mark the 252 mya event on a class timeline, then let students use Table 1 and the graph on their own.

Curriculum

NGSS standard covered

MS-LS4-1

Read the fossil record for patterns in the existence, diversity, extinction and change of life over Earth's history.

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Six Legs Through Time: The Insect Club's Fossil Case

Read the insect fossil record for new groups, losses and recovery.

Part 1: When insect groups appear

Read the passage and Table 1, then answer questions 1 to 4.

Building the Fossil Case

1The entomology club at Larchmont Middle School studies insects. Members raise mealworms, keep a beehive with help from a local beekeeper and pin their best finds in glass cases. This spring, the club's adviser, Ms. Celestine Obuya, borrowed a set of insect fossil casts from the state geological survey. Club members Mirela Kovač and Tobin Achterberg are building a hallway case called "Six Legs Through Time" that puts the casts in order from oldest to youngest.

2Insects are hard to fossilize, because most are small and their bodies break down quickly. The best insect fossils formed where a body was buried fast in fine mud at the bottom of a lake, or where an insect was trapped in sticky tree resin that later hardened into amber. The ages of the rocks and amber come from the layers they lie in and from measurements of certain elements in nearby volcanic ash. Scientists give these ages in millions of years ago (mya). Often a single wing is all that is left, but that can be enough, because the pattern of veins in a wing differs from one insect group to another. The oldest insect fossils known are about 400 million years old.

3Table 1 lists the oldest and youngest known fossils of seven insect groups. Griffinflies were relatives of today's dragonflies. Some had wings that spread about 70 cm from tip to tip, more than three times the wingspan of any living dragonfly. The oldest known fossils of flowering plants are about 130 million years old.

4About 252 million years ago, Earth went through the largest mass extinction in its history, often called the Great Dying. Most kinds of sea animals and many kinds of land animals and plants disappear from the fossil record at that time.

5Scientists sort insects into large groups called orders. Beetles are one order, true flies are another, and so are moths and butterflies. Tobin found a chart of how many insect orders are known from fossils at different times, and the club decided to hang it above the case as a graph. Mirela added a note: the counts depend partly on how many rocks of each age have been searched for insect fossils.

Table 1: Seven Insect Groups in the Fossil Record (approximate ages)
Insect group	Oldest fossils (mya)	Youngest fossils
Griffinflies	320	about 252 mya
Mayflies	315	Still living
Beetles	300	Still living
True flies	240	Still living
Moths and butterflies	200	Still living
Ants	100	Still living
Bees	100	Still living

Use Table 1. Compare the oldest beetle fossils with the oldest ant fossils.

Beetles appear in the fossil record about million years before ants.

Which statement best describes the pattern in Table 1?

A. The seven groups first appear within about 10 million years of each other.
B. The groups first appear at different times, and one of them later disappears.
C. The groups first appear in order from the smallest insects to the largest.
D. The groups that first appear after 252 mya later died out.

Use Table 1 and paragraphs 3 and 4. What does the griffinfly record suggest?

A. Griffinflies shrank over time and are still living today as small dragonflies.
B. Griffinflies lived for about 68 million years and likely died out around the Great Dying.
C. Griffinflies lived alongside bees and ants for about 150 million years.
D. Griffinflies first appeared just after the Great Dying, when many other insects were gone.

Use Table 1 and paragraph 3. Many bees today feed on nectar and pollen from flowers. Which inference fits the fossil ages best?

A. Bees first appear before beetles, so they were among the first insects.
B. Bees and flowering plants first appear at the same time, about 200 million years ago.
C. Bees first appear before flowering plants, so flowers likely evolved to feed bees.
D. Flowers were already about 30 million years old when bees first appear.

Part 2: Counting insect orders

Use the graph, Table 1 and the passage to answer questions 5 to 11.

Past counts come from fossils. The count for today includes orders known only from living insects.

Use the graph. Compare the counts at 260 mya and 245 mya.

The number of known insect orders fell by orders.

Use the graph and your answer to question 5. Round to the nearest whole percent.

The drop from 260 mya to 245 mya was about % of the orders known at 260 mya.

Which statement best describes the pattern in the graph from 310 mya to today?

A. The count fell steadily from 310 mya to today.
B. The count peaked at 100 mya and has fallen since then.
C. It rose, dropped sharply once, then rose again.
D. The count stayed near 20 orders the whole time.

Use the graph, Table 1 and paragraphs 4 and 5. Which statement about the drop between 260 mya and 245 mya is best supported?

A. The drop fits many insect groups dying out at the time of the Great Dying.
B. The drop shows that insects grew larger after 252 mya than before it.
C. Insect orders fell from 28 to 20 because each insect changed its order.
D. The 8 missing orders moved into the sea, where their fossils formed instead.

Circle the two results that are evidence that insect diversity recovered after the Great Dying.

The count of orders today, 30, is higher than the 28 at 260 mya.The youngest griffinfly fossils are about 252 million years old.The count of orders rose from 20 at 245 mya to 26 at 100 mya.The oldest insect fossils are about 400 million years old.Some griffinflies had wings about 70 cm across.

10.

Tobin gets a new cast from a lake rock that is about 150 million years old. Based on Table 1, which insects could the club expect to find in rocks of that age?

A. Beetles, true flies and moths, but no ants or bees
B. Ants, bees and moths, but no beetles or flies
C. Beetles, true flies and griffinflies, but no ants
D. Mayflies, griffinflies and bees, but no moths

11.

A visitor to the hallway case says, "Insects are the same today as when the first ones appeared 400 million years ago." Write a claim that answers the visitor. Give at least two pieces of evidence from Table 1 and the graph, and explain your reasoning.