People say “the dinosaurs” as though they all lived together. The gap between Stegosaurus and Tyrannosaurus is longer than the gap between Tyrannosaurus and us — and students work that out themselves from the atlas dates rather than being told.
They then scale the whole Mesozoic onto a line, match the periods to the official international colour scheme, and find where human history sits on a one-metre rope. It is thinner than a pencil mark.
Three pages: two student sheets and a teacher page with answers.
People say “the dinosaurs” as though they all lived together. They did not. The gap between Stegosaurus and Tyrannosaurus is longer than the gap between Tyrannosaurus and you.
Find each dinosaur in the atlas and write down when it lived. The dossier gives a range in millions of years ago (Ma).
| Dinosaur | Lived from (Ma) | to (Ma) | Period |
|---|---|---|---|
| Eoraptor | |||
| Stegosaurus | |||
| Tyrannosaurus rex | |||
| My own choice: |
| Stegosaurus died out about | Ma | |
| T. rex first appeared about | Ma | |
| So the gap between them is | million years | |
| T. rex died out about | Ma | |
| So the gap from T. rex to now is | million years |
Write what that tells you about the phrase “the age of the dinosaurs”.
The Mesozoic ran from about 252 to 66 Ma — roughly 186 million years. Squeeze all of it onto the line below, where the whole line is 186 million years and every centimetre is about 10 million.
Mark each of your four dinosaurs on the line with an arrow and its name.
The atlas colours the three periods of the Mesozoic. These are not decorative — they are the standard colours geologists use worldwide. Find them on the atlas timeline and shade the bar below to match.
| Period | When (Ma) | Colour from the atlas |
|---|---|---|
| Triassic | 252–201 | |
| Jurassic | 201–145 | |
| Cretaceous | 145–66 |
Which period was longest? Which of your dinosaurs lived in it?
How far from the “today” end would you tie a knot for T. rex? Show your working.
And where would all of human history go?
Deep time is genuinely difficult. Numbers in the millions stop meaning anything, and children (and adults) collapse the entire Mesozoic into a single crowded era where every dinosaur coexisted. This sheet attacks that directly with one fact that reliably lands: Stegosaurus is further from T. rex than T. rex is from us.
| Dinosaur | Lived (Ma) | Period |
|---|---|---|
| Eoraptor lunensis | about 231–228 | Late Triassic |
| Stegosaurus stenops | about 155–150 | Late Jurassic |
| Tyrannosaurus rex | about 68–66 | Late Cretaceous |
The intended realisation: “the age of the dinosaurs” is not an era, it is a span longer than everything that has happened since, containing animals as distant from each other as they are from us.
One metre for 252 million years gives about 2.52 million years per centimetre. T. rex’s extinction at 66 Ma sits 66 ÷ 2.52 ≈ 26 cm from the “today” end. Accept 25–27 cm.
Human history is the point of the second half. Anatomically modern humans at roughly 300,000 years is about 0.12 mm — thinner than a pencil line. Recorded history, some 5,000 years, is about 2 microns: invisible. Students frequently refuse to believe this and check it twice, which is exactly the desired outcome.
The atlas uses the International Chronostratigraphic Chart palette published by the International Commission on Stratigraphy: Triassic purple, Jurassic blue, Cretaceous green. They are lightened slightly for legibility on a dark screen, but the hues are the international standard. A geological map from any university will use the same scheme, and students can check that for themselves.
The Cretaceous is longest at about 79 million years, then the Jurassic at 56, then the Triassic at 51.
| Curriculum | Strand |
|---|---|
| New Zealand | Planet Earth and Beyond — Earth systems: geological time. Mathematics — Measurement: scale and proportion. |
| England (KS2–KS3) | Rocks and fossils; the geological record; Maths — scale factors, large numbers, converting units. |
| NGSS (USA) | MS-ESS1-4 — construct a scientific explanation based on evidence from rock strata for how the geologic time scale is used to organise Earth’s history. 4-ESS1-1. |
| Australia | Earth and Space Sciences — the geological timescale; Mathematics — scale, ratio and very large numbers. |