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history of earth

© elasmo holdings pty ltd

© elasmo holdings pty ltd


Why is History important?

Here is what we think.

History provides us with solutions to many of the problems of the present. It allows us to reflect and learn from those before us.

It is a tool that we can draw inspiration from. History teaches us that things can change and from this perhaps we can find courage. When pressed against the present it can become so easy to feel overwhelmed. However, when we delve into history we can draw inspiration from those before us. Those that made decisions, created movements and inventions whose waves are still felt today.

It also gives us a sense of place, and where we have come from. Connecting us to every person and creature, everything living thing that has shared this remarkable planet with us.

Millions of years ago the world was home to lots of different plants and animals. However, some of those plants and animals looked very different to the ones you and I are familiar with.


How do we know they existed if we, as humans, were not around?


A fossil is the preserved remains or traces of a dead organism. The process by which a fossil is formed is called fossilisation.

It’s very rare for living things to become fossilised. Usually after most animals die their bodies just rot away and nothing is left behind. However, under certain special conditions, a fossil can form.

After an animal dies, the soft parts of its body decompose leaving the hard parts, like the skeleton, behind. This becomes buried by small particles of rock called sediment.

As more layers of sediment build up on top, the sediment around the skeleton begins to compact and turn to rock.

The bones then start to be dissolved by water seeping through the rock. Minerals in the water replace the bone, leaving a rock replica of the original bone called a fossil.

© elasmo holdings pty ltd

© elasmo holdings pty ltd


Scientists who search for and study fossils are called Palaeontologists.

Paleo meaning old

Ontology meaning the study of existence

Palaeontologists learn about the ancient world! Fossils provide evidence for how living things and the environment have changed over time.

Fossils have been found in rocks of all ages, stretching back billions of years. However, most of the species found in the fossil record have died out or become extinct.

Fossils don’t just show how living things have changed; they can also help us understand how the Earth has changed.

Over millions of years the Earth’s surface shifts and changes. For example, rocks that once formed the seafloor might be forced up to form a mountain range. This means that you can sometimes find the fossils of sea creatures at the peak of a mountain.

Geological Time Scale

Scientists who study the structure and history of Earth are called geologists. Geologists study rocks and fossils, or remains of living things that have been preserved in the ground. The rocks and fossils tell the story of Earth from when its crust formed 4.5 billion years ago to the present. Geologists have mapped out a time scale that is a “calendar” of Earth’s geologic history. This calendar is called Geological Time Scale.

© elasmo holdings pty ltd

© elasmo holdings pty ltd


Let’s go back in history and take a look at some of the cool creatures that once roamed our ocean.

First let’s take a look at one that looks very similar to a creature that currently calls our ocean home.

Sharks have been swimming and hunting in the worlds oceans for 420 million years! By the time Dinosaurs evolved, around 220 million years ago sharks had already been around for 200 million years.

During the Miocene period one very big Shark patrolled the ocean.

© elasmo holdings pty ltd

© elasmo holdings pty ltd

This 50-foot (15 - 18m) shark (elasmobranch) is known as Megalodon. Megalodon patrolled our ocean for 13 million years during the Miocene period, and, where pro whale eating machines, their prey also included other large sea creatures. Given their vast size and powerful bite force it is suggested that 'The Meg' may have been one of the most powerful predators ever to have existed. 

Before megalodon was correctly identified as a shark, its teeth were thought to be rocks that had fallen from the moon or the petrified tongues of dragons and giant serpents.

Over the years, many fossilized whalebones have been found with signs of bite marks that match megalodon's massive pearly whites. These triangular teeth could be over 7 inches in length! Reconstructions of the megalodon’s jaw suggest it may have been up to 7 feet across (2.1 meters) by  11 feet (3.4 metres) and lined with around 276 of these 7-inch gnashers.

Bite force? I am glad you asked. 
Humans have been measured with a bite force of around 1,317 Newtons (N), while great white sharks have been predicted to be able to bite down with a force of 18,216N. Researchers have estimated that megalodon had a bite of between 108,514 and 182,201N. 

Although the Megalodon no longer exists, Sharks have been every good at Surviving changes in Earth’s climate.

© elasmo holdings pty ltd

© elasmo holdings pty ltd

Meet elasmosaurus (EE-LAZMO-SORE-us) 

A poster lizard which still holds a somewhat mythical status is the ‘Loch Ness Monster” which bares remarkable resemblance to the elasmosaurus. Elasmosaurus lived during the Cretaceous period. At close to 15.2 metres and up to three tonnes, the Elasmosaurus was one of the biggest plesiosaurs of the Mesozoic Era. Elasmosaurus had the longest neck of any plesiosaur yet identified, about half the length of its entire body and supported by a whopping 71 vertebrae!

Elasmosaurs, although beautifully adapted to aquatic life, were still reptiles, and thus had lungs rather than gills, meaning they had to surface to breath. Despite many depictions showing this majestic reptile holding it's neck elegantly out of the water, palaeontologists have concluded that, given the enormous size and weight of its neck, Elasmosaurus was incapable of holding anything more than its tiny head above the water.  

Do you know how many mass extinctions there have been on Earth?


In the history of this planet we know of five mass extinction events, when the majority of life on Earth disappeared.

Sharks have survived all five of these! The scary thing is that now many types of sharks are threatened by hunting and pollution caused by humans. Shark numbers are dropping everyday. In fact 161 sharks are killed a minute!

Extinction is the termination of an organism or of a group of organisms, usually a species. The moment of extinction is generally considered to be the death of the last individual of the species.

During the Five mass extinctions events we saw 70 - 90% of species disappear.


  1. Dovician - Silurian (450 million years ago)

    The second largest of the five major extinction events, saw an estimate of 85% of all Ordovician species disappear. With global cooling and falling sea levels.

  2. Late Devonian (365 million years ago)

    The late Devonian eliminated 70 to 80% of all animal species, caused by several stresses such as; lack of oxygen, rapid global warming or cooling and meteorite or comic impacts.

  3. End Permian (250 million years ago)

    This event wiped out 96% of Earths species. Nicknamed the ‘Great Dying’. Less than 5 percent of the animal species in the seas survived. Possibly caused by an asteroid that hit just below Australia.

  4. Triassic - Jurassic (200 million years ago)

    This event saw the demise of 76% of all marine and terrestrial species. The dinosaurs, pterosaurscrocodilesturtlesmammals, and fishes were little affected by the transition. This event still remains a matter of considerable debate. Many scientists predict that this event was caused by climate change and rising sea levels resulting from the sudden release of large amounts of carbon dioxide.

  5. Cretaceous - Paleogene (66 million years ago)

    Known at the K-T extinction global extinction event responsible for eliminating approximately 80 percent of all species of animals. The extermination of the dinosaurs has been a puzzle to paleontologists, geologists, and biologists for two centuries, however rocks of that age contain traces of an asteroid that struck Earth, generating catastrophic events.

© elasmo holdings pty ltd

© elasmo holdings pty ltd

The most recent of the big five was an Asteroid that saw the extinction of the Dinosaurs. Guess what, we are in the sixth mass extinction and perhaps this time we are the Asteroid,

Even when things are going well on Earth, there is a background rate of extinction. Among mammals we’d except to see one species go extinct every 700 thousands years. Studies of current extinctions rates say that we are 1000 x past that. There are a lot of species we haven’t even discovered or identified yet so these numbers are probably underestimated.

Along the way we have been altering the world around us. No living thing as ever altered life on Earth to the degree we have, which is why the Sixth Mass extinction is known as the Anthropocene Defaunation.

Anthropocene: of, relating to, or resulting from the influence of human beings on nature.

Defaunation: Used to denote the loss of both species and populations of wildlife.

While deforestation is a term that is now readily recognised, and influential in focusing scientific, and general public attention on biodiversity issues, (particularly as remote sensing technology provides rigorous quantitative information and compelling images of the magnitude, rapidity, and extent of patterns of deforestation). Defaunation is a term that remains a largely cryptic phenomenon.

“In less than two generations of humans, the populations of vertebrate animals have dropped by 52% between 1970 and 2010”

how the earth has changed

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© elasmo holdings pty ltd

Over the 4.5 billions years that Earth has existed it has gone through many changes.

Today for example there are five oceans that cover just over 70% of our planet, and they are all connected together:

  • the Atlantic Ocean

  • the Pacific Ocean

  • the Indian Ocean

  • the Southern Ocean

  • the Arctic Ocean

Our planet has always been covered in ocean but the world map hasn’t always looked this way!

Around 240 millions years ago all the continents we see today were joined! Forming a supercontinent known as Pangea.

Over time the continents have slowly drifted further and further apart! But why?

© elasmo holdings pty ltd

© elasmo holdings pty ltd

This shift in Continents is believed to be because of Plate tectonics. Plate tectonics make up the Lithosphere. (Remember we looked at this in the Planet Earth workshop).

Plate tectonics is the theory that Earth's outer shell is divided into several plates that glide over the mantle. According the the World Atlas there are 9 major plates. These constantly shifting plates have formed mountains ranges, created oceans, formed supercontinents and ultimately created Earth as we know it today.

into the ocean

With 70% of our planet covered in water, the ocean is a vital to life on Earth. Take a deep breathe in. Some of oxygen that is filling your lungs has come from the ocean!

The world’s oceans include warm waters and icebergs, shallow reefs and deep dark trenches. Different type of sea life like different kinds of ocean. Scientists have organised the ocean into layers. Each layer is usually distinguished by the amount of sunlight it receives.

These five layers are

  • The Sunlight Zone

  • Twilight Zone

  • Midnight Zone

  • Abyssal Zone

  • Trench Zone

© elasmo holdings pty ltd

© elasmo holdings pty ltd


© elasmo holdings pty ltd

© elasmo holdings pty ltd

Coral reefs are like busy underwater cities, home to thousands of fish and other animals. The biggest coral reef in the world is the Great Barrier Reef which is here in Australia! It is 20,000 years old and is so large it can be seen from space.

Coral reefs only cover 1% of the ocean but amazingly 25% of all sea creatures live on or very near a reef!

Coral is very sensitive to dirty water and changes in temperature. Coral reefs are one of the most endangered habitats in the world.

Threats to our ocean

Some of the threats the ocean is currently facing is;

  • Climate Change

    Increased Carbon emission is causing the temperature and pH balance of the Ocean to shift. Higher temperatures in the Ocean have devastating effects on marine life such as coral bleaching, migration patterns of fish and the loss of habitat for polar species like penguins, polar bears and seals. Melting ice caps increase combined with warmer waters is causing rising sea levels.

  • Ocean Acidification

    Ocean acidification affects whole ecosystems, such as coral reefs, which depend on the formation of calcium carbonate to build reef structure, which in turn provides homes for reef organisms.

  • Chemical Pollution

    Eighty percent of pollution to the marine environment comes from the land. One of the biggest sources is called non-point source pollution, which occurs as a result of runoff. Non-point source pollution includes many small sources, like septic tanks, cars, trucks, and boats, plus larger sources, such as farms, ranches, and forest areas. Millions of motor vehicle engines drop small amounts of oil each day onto roads and parking lots. Much of this, too, makes its way to the sea.

  • Plastic Pollution

    Currently, it is estimated that by 2020 there will be more plastic in the ocean than fish. The very traits that made plastic revolutionary are also the reason it has become one of the greatest threats to life on Earth.

  • Noise Pollution

    Underwater acoustical communication networks, military sonar, seismic airgun surveys, seafloor oil and gas processing, and shipping noise are having a profound effect on Marine life, such as whales and dolphins rely on sound to navigate their world.

  • Over Fishing

    Fishing is one of the most significant drivers of declines in ocean wildlife populations. Catching fish is not inherently bad for the ocean, except for when vessels catch fish faster than stocks can replenish.

  • By-Catch

    Wherever there is fishing, there is by-catch—the incidental capture of non-target species such as dolphins, marine turtles and seabirds. Thousands of miles of nets and lines are set in the world's oceans each day.

  • Habitat destruction


There is 7.7 billion people on Earth, but there is only 1 you.

You DON’T need super powers to save the planet. The little choices that we make every single day really do have such a large impact.

You are the new philosophers, the change drivers, the discoverers, the scientists, researchers, artists, influencers. Humans have this incredible ability to love, to feel compassion and empathy and, never forget the power of imagination!

There is an vast ocean of possibilities and you are a new wave. 

© elasmo holdings pty ltd

© elasmo holdings pty ltd



Let’s spend some time with our imaginations and design our own Dinosaur.


  • The environment he or she might live in, what features will they need to survive this environment? Perhaps they require camouflage or long fur or scales?

  • Their diet - are they a herbivore (plant eater) or carnivore (meat eater). If they are a herbivore they would need teeth perfect for chopping on leaves just like Horses. If they eat meat they will need sharp teeth like a lion.

  • Are they a predator (A living animal that hunts and kills in order to survive) or prey (Living animals that are hunted and killed by other animals) what features will they need to protect them? Do they have a spiky body like a Stegosaurus or sharp claws like a Raptor?

  • Anatomical features - horns, how many legs? how many eyes? big nose?


You can draw inspiration from other animals like

  • Dinosaurs

  • Birds of Paradise


Additional Learning

Seismic Testing

Series and Docos


A plastic Ocean

Our Planet