Evolution education resource
From land to sea
Whales are mammals, like you, and their ancestors once lived on land. So how did they come to be in the sea?
This astounding transition came shortly after the rise of modern mammal groups, around fifty-five million years ago, during a hot period in the Earth's history. Dinosaurs and large marine reptiles had disappeared some millions of years previously.
One group of hoofed mammals spent more and more time in the water, living on the abundant food there. Eventually they left the land altogether - to become whales.
Find out more about whale evolution.
At the exhibition
Introduce students to this section about the evolution of whales.
Explore the immediate area
Gather the students back to discuss the following questions and topics.
Questions for 5 to 10 year olds
- Introduce the concept of evolution to students.
- Discuss how change can occur over many generations.
- Play “spot the difference.” What are the differences between Pakicetus and Dorudon?
- Why did these changes occur?
Questions for 10 years old and over
Introduce the concept of evolution to students.
- Discuss how change (or mutations) can occur over many generations or simply in one generation.
- What are the differences between Pakicetus and Dorudon?
- Is it possible that future changes will occur in whales? If so what might these changes be?
- How might future climate change affect the lives of whales?
- Discuss adaptation. How have whales adapted to their changing evironments?
Teachers’ notes:
Scientific evidence shows us that whales were once land mammals. They moved into the water in part because of environmental factors – a hot period on Earth. These early whales are known collectively as Archeocetes, or ancient whales. Recent molecular and fossil discoveries shows the relationship of whales to even-toed ungulates (the artiodactyls) , that include cows, sheep, hippopotamus etc.
Features of it’s ear bones, that are unique to the Order cetacea, sugests that Pakicetus is the earliest known ancestor of modern whales.
The Ambulocetus lived in water but would have come ashore to breed..
The Kutchicetus had greatly reduced hind legs, and a large flattened tail that was probably used for swimming. These whales would have swum in much the same way as modern otters.
The basilosaurids were fully aquatic with paddle-like flippers, and only rudimentary hind limbs. The shape of the bones at the tips of their tails show evidence that they possessed tail flukes.
The earliest filter feeding baleen whales (Mysticeti) and the Echolocating toothed whales (Odontoceti), the groups of whales that we see today, appear at about 35million years ago at ime when great cooling happened on earth that saw the development of the oceanic current systems we see today and the formation of polar ice, the creatures that evolved into whales moved into the water during a period when the Earth’s climate was very hot. They took to the sea to feed on the abundant resources there.
Artist’s impression of Pakicetus attocki by Carl Buell, reproduced courtesy of Carl Buell
Artist’s impression of Ambulocetus natans by Carl Buell, reproduced courtesy of Carl Buell
Artist’s impression of Kutchicetus minimus by Carl Buell, reproduced courtesy of Carl Buell
Artist’s impression of Dorudon atrox by Carl Buell, reproduced courtesy of Carl Buell
Artist impression of Waipatia by Anton van Helden
Artist impression of Squalodon by Anton van Helden
Evolution timeline, from 50 million years ago to date