25 Most Important Events in the History of Earth’s Formation (Part 2)

The first “intimate encounter” likely took place around 1.2 billion years ago. While our blue planet, home to over 7 billion people, once resembled a snowball, similar to some of Jupiter’s moons. In this second part, we will continue to follow the evolutionary history from 375 million years ago.

13. The First Amphibians | 375 million years ago

Some vertebrate species were “enticed” by food sources like insects.

After plants established themselves on land, animals were quick to seek new “homes.” First, insects crawled onto land around 400 million years ago. However, vertebrates soon followed, such as Tiktaalik, a fish resembling a salamander but with fins adapted as limbs.

Fish like Tiktaalik eventually evolved into fully four-legged creatures, serving as ancestors for amphibians, reptiles, and later mammals. Their departure from water is seen as fortuitous, as it coincided with the end of the Devonian extinction event, which eliminated many aquatic species, including enormous fish with armoured bodies.

14. The Dawn of Reptiles | 320 million years ago

They may look similar, but the first reptiles were not dinosaurs.

When the first reptiles appeared, Earth was experiencing a prolonged cold period known as the Late Paleozoic Ice Age. Reptiles evolved from amphibians that had a salamander-like appearance. However, unlike their ancestors, reptiles had thick, scaly skin and laid eggs with hard shells, distinct from their aquatic origins.

Thanks to these advantages, reptiles quickly became the dominant land animals. Even though some species were incredibly large, like Dimetrodon, measuring up to 4.5 meters long, they were still reptiles and not dinosaurs. The age of dinosaurs was still far off.

15. The Supercontinent Pangaea | 300 million years ago

There was a time when the division between land and water was very clear.

For the last time until now, Earth’s continents merged to form a supercontinent known as Pangaea, surrounded by a super-ocean called Panthalassa.

This “superpower” phase lasted for 175 million years. Ten million years later, the continents separated once again, leading to the formation of what we see today.

16. The Largest Mass Extinction | 252 million years ago

Mass volcanic eruptions posed a threat to many life forms.

Although not the first mass extinction, the end-Permian extinction posed the greatest challenge to life on Earth. It is estimated that up to 96% of marine species and an equivalent number of terrestrial species vanished during this period.

The exact cause of this extinction remains uncertain. However, archaeological data suggest that a series of massive volcanic eruptions, known as the Siberian Traps, covered 2 million square kilometers of Earth’s surface in lava, filled the atmosphere with toxic smoke, and raised ocean temperatures to 40 °C, potentially making it the culprit.

The recovery of life following this event ushered in a new era – the Age of Dinosaurs.

17. The First Mammals | 220 million years ago

Mammals emerged alongside dinosaurs but couldn’t compete.

At the same time dinosaurs evolved and flourished worldwide, the first mammals made their appearance. Their ancestors were reptiles called cynodonts, which had dog-like features and some may have been covered in fur.

The first mammals, such as Morganucodon, were relatively small and rodent-like. They likely operated at night when reptiles were dormant. There is a hypothesis that this nocturnal lifestyle encouraged mammals to evolve towards warm-bloodedness, allowing them to maintain a stable body temperature to forage while reptiles were less active at night.

18. The Triassic Extinction | 201 million years ago

Despite a major extinction event, dinosaurs continued to recover and dominate.

The Triassic period was when dinosaurs roamed the Earth, while massive reptiles like Ichthyosaurs dominated the oceans as top predators. However, another extinction event occurred.

The cause of this extinction has not been determined, but its consequences were dire, with 80% of species wiped out. Yet shortly after, dinosaurs recovered and continued to dominate the land, even reaching enormous sizes. The largest ever recorded, Dreadnoughtus schrani, weighed nearly 60 tons.

19. The First Birds | 160 million years ago

Feathered animals are the descendants of dinosaurs today.

Life conquered all realms: first the water, then the land, and finally the sky. Birds did not evolve from mammals but are descendants of dinosaurs. Feathered dinosaurs, such as Velociraptors, are the ancestors of modern birds, possessing snouts instead of hard beaks and limbs for grasping trees instead of wings.

One of the most famous early birds, Archaeopteryx, lived 150 million years ago. However, recent archaeological findings in China suggest that species like Xiaotingia and Aurornis appeared even earlier.

20. Flowering Plants | 130 million years ago

It took a long time after reaching land for forests to bloom with flowers.

It may sound strange, but flowers are the latest “invention” of the plant kingdom. Although plants began to sprout on land 465 million years ago, no flowers were recorded for over two-thirds of that time.

Flowering plants seem to have emerged during the age of dinosaurs. Meanwhile, grass-like species only appeared much later. The oldest fossils of grass are just 70 million years old. Of course, grasses could have existed before that for some time.

21. The Death of the Dinosaurs | 65 million years ago

The meteorite impact is considered the cause of dinosaur extinction.

BOOM… and you go extinct. 65 million years ago, a massive rock from outer space struck Earth in what is now Mexico. The collision was catastrophic, but the long-term consequences were even worse.

The dust was blasted into the upper atmosphere, blocking sunlight and ushering in a cold and dark period across the entire planet. Dinosaurs, being the most populous, naturally suffered the most. Other large reptiles and predatory species were also wiped out. However, smaller species managed to survive due to their lower food requirements.

This was the fifth mass extinction recorded in history and the last one to date.

22. The First Primates Emerge | 60 – 55 Million Years Ago

Human ancestors began as tree dwellers.

The disappearance of most dinosaur species allowed mammals to thrive and diversify. They quickly evolved to have wombs and give birth to live young, thanks to placentas. However, there was still a considerable period before the emergence of humans.

Some mammals began evolving to climb and live in trees as a means of avoiding other predators. This led to the emergence of monkeys, apes, and ultimately humans. However, the first primates were quite small. The oldest primate fossil belongs to a species called Archicebus achilles, weighing less than 30 grams. They primarily lived in the humid tropical forests of Asia.

23. Super Photosynthetic Plants | 32 – 25 Million Years Ago

C4 plants are primarily monocots, with grasses being the most prevalent.

Plants began harnessing solar energy to synthesize sugars over billions of years through a process known as photosynthesis. However, it wasn’t until recently that some species “discovered” a more efficient form of photosynthesis called C4.

C4 photosynthesis is more effective than the common C3 photosynthesis. As a result, C4 plants can better adapt to harsh environmental conditions. Today, botanists are working on genetically modifying rice plants to use C4 photosynthesis, aiming for higher yields to support an ever-growing population.

24. The First Hominids | 13 – 7 Million Years Ago

Human ancestors began their cries of life in Africa.

The first apes appeared in Africa around 25 million years ago. At some point, they began to diverge into the ancestors of modern apes and modern humans.

It’s difficult to pinpoint the exact timing of this event, but through archaeology and genetic biology, we can estimate it relatively well. The oldest known hominid is Sahelanthropus tchadensis, which lived on land 7 million years ago.

25. Modern Humans | 200,000 Years Ago

Despite a brief existence, humans have dramatically changed the Earth.

We, Homo sapiens, are relatively young compared to all preceding species, having only existed for one-fifth of a million years compared to the 7 million years of Sahelanthropus tchadensis. Yet, in this “short” time, we have left our birthplace in Africa and traveled to every continent on the planet. We have even ventured into outer space, something no previous species had achieved.

However, with our accomplishments, we have also caused significant damage to this planet. In just the last 40 years, 50% of wild animals have vanished from Earth, faster than any recorded extinction event (or mass extinction) in history.

Will the sixth mass extinction occur during this human era? Is the 4 billion-year history of life on this planet destined to end at the hands of humanity?

• 25 Most Important Events in Earth’s Formation History (Part 1)
• The History of Earth Through Images (Part I)
• The History of Earth Through Images (Part II)