Flora and Fauna of Sahul

Flora and Fauna of Sahul: A Unique Ecosystem

Scientists have discovered something reminiscent of Atlantis near Australia. There was once an entire continent now submerged underwater. Around 70,000 years ago, during the last Ice Age, a massive landmass called Sahul existed in the southwestern Pacific Ocean. This ancient supercontinent connected what we now know as Australia, New Guinea, Tasmania, and the Aru Islands into one vast piece of land.

Imagine lush tropical rainforests surrounded by beautiful mountains, with the tallest peaks in the New Guinea Highlands reaching over 13,000 feet. This stunning place was home to various unique animals, mostly marsupials, but not just koalas and kangaroos. Sahul hosted different types of grazers, burrowers, scavengers, and predators, including the huge Diprotodon, the powerful hunter Thylacoleo, and the terrifying Megalania, much larger than any living lizard today. While the rest of the world was filled with placental animals like wolves, elephants, and humans, Sahul's only typical mammals were bats and rodents.

The regions of Arafura and Carpentaria in Sahul were covered by hot savannah and dry forests, resembling modern Australia’s hot deserts with scrub steppe and temperate forests along the eastern coast. During this time, people were migrating worldwide. From 60,000 to 45,000 years ago, they embarked on an incredible journey from Southeast Asia to Sahul, traveling by foot and using bamboo rafts and simple boats. They came from an ancient landmass called Sunda, including parts of Southeast Asia, traversed a series of islands known as Wallacea, and eventually spread across Sahul. This journey was no small feat—Sahul was about 4.1 million square miles, larger than the USA or Canada, stretching from the equator to the southern part of New Zealand. These travelers became Australia's first people.

Sahul had a population of about half a million. We've discovered cave paintings dating back around 40,000 years, depicting hunting scenes with figures of humans and animals. Researchers are investigating how these early settlers moved across Sahul and where archaeological evidence of their journey might be found. They created a landscape evolution model showing how Sahul changed between 75,000 and 35,000 years ago, revealing potential migration routes and archaeological sites. Humans likely traveled along coastlines and rivers.

But how did Sahul get submerged, similar to the mythical Atlantis? During the last Ice Age, much of the Earth's water was locked in ice sheets and glaciers, lowering sea levels. As global temperatures increased, the ice sheets melted, and sea levels rose, flooding the land bridges that once connected different parts of Sahul. About 8,000 years ago, New Guinea separated from mainland Australia, and around 6,000 years ago, Tasmania did the same.

Today, we can explore the underwater parts of Sahul thanks to new technology. Divers collect samples from the ocean floor, underwater drones explore places too deep or dangerous for humans, and sonar mapping uses sound waves to create maps of the ocean floor. Archaeologists have found stone tools, other artifacts, and fossils of animals like Diprotodon and Thylacoleo. By studying the underwater terrain of Sahul, they've learned about the ancient rivers, lakes, and coastlines that existed during the Ice Age.

Sahul isn't the only underwater continent. Sundaland, made up of Sumatra, Java, Borneo, and other islands, was a massive landmass during the Ice Age, now almost fully submerged. The parts above water are rich in biodiversity, home to nearly a fifth of the world's bird species and a fourth of Earth's fish species. Sundaland waters are a haven for marine life, and its land teems with unique flora and fauna.

Similarly, Zealandia, a long narrow piece of land about half the size of Australia, broke from Antarctica around 100 million years ago. Today, 7% of it remains above sea level, forming New Zealand, Stewart Island, and smaller islands. Zealandia is lush and warm, with volcanoes, mountain ranges, natural geysers, and hot springs.

Another hidden world is Argoland, which broke off from Australia around 155 million years ago. It drifted north, reaching Southeast Asia before disappearing. Scientists recently found its remains in the Sunda Trench and other regions, buried under Indonesia and Myanmar.

Greater Adria, once the size of Greenland, broke away from the supercontinent Gondwana about 240 million years ago, moved north, and crashed into Europe, shattering into pieces. Some fragments became part of mountain ranges like the Alps, scattered across more than 30 countries.

The Seychelles were also once part of Gondwana, sitting on top of the ancient continent. These islands broke off from India and Madagascar, becoming isolated in the Indian Ocean. Mascarene Plateau, another hidden land, broke off from India after the dinosaurs went extinct, stretching into a long ribbon-like shape and now scattered beneath the Indian Ocean.

Scientists continue to discover hidden continents worldwide, hinting at more underwater worlds yet to be found.