What was Gondwana?
Gondwana was a huge megacontinent that formed as smaller landmasses squeezed together, long before life inhabited the lands of Earth. If you were to visit the once megacontinent you could walk from South America across Antarctica and Africa to the east coast of Australia, without encountering an ocean. None of our familiar continents existed in their current forms when the first dinosaurs walked on Earth, first Pangaea then Gondwana had to tear into pieces to form the continents of our human world. Gondwana means Land of the Gonds, the name of a tribe in India, and a region in India named after this tribe. To avoid confusion, the official name of the ancient megacontinent is Gondwanaland, but the nickname Gondwana is more commonly used to refer to the ancient megacontinent that hosted some of the first plants and animals, and recorded the evolution of the first dinosaurs and the first marsupials. It existed for approximately 250 million years, before and after Pangaea Supercontinent, and included all of modern day Australia, India, Antarctica, Zealandia, Africa, Madagascar, and South America. It was huge!
While few people are aware of Gondwana’s role in Earth history, many people are familiar with Pangaea, the last supercontinent. Many assume Pangaea was the first supercontinent, but it was only the most recent in a 3 billion year lineage of supercontinents that form when the majority of the Earth's continental crust converge into a single landmass. Before Pangaea formed, two megacontinents existed, Gondwana and Laurussia/Laurasia/Euramerica. Euramerica was the accumulation of most of the northern hemisphere continents, while Gondwana was the only major southern hemisphere landmass. The names of these past megacontinents are not always agreed upon (I like the name Euramerica the most), nor are the exact definitions of the words supercontinent or megacontinent. Supercontinent is often defined as “a landmass made up of most or all of Earth’s land” (Encyclopedia Britannica), while megacontinents are relatively smaller. One study suggests that megacontinents are precursors to the formation of supercontinents, and the only current megacontinent is Eurasia (Europe + Asia). In my humble opinion, the greatest of all megacontinents was Gondwana because it existed for so long and provided a refuge for land life to survive and adapt in a tumultuous world.
Starting approximately 800 million years ago India, Madagascar, & East Africa collided, and by 530 million years ago South America, Australia, Antarctica, and Africa had joined the Gondwana megacontinent. It formed in the southern hemisphere and hosted the Ediacaran lifeforms fossilized in the Ediacaran Hills of Australia. Fossils of these Gondwanan ancient lifeforms were the predecessors of animals and plants, and have also been discovered in Africa & South America.
Gondwana hosted and recorded the Cambrian explosion of marine life, the evolution of animals with skeletal features. In the shallow waters atop the continental shelves of Gondwana evolved the predecessors of modern Cephalopods (squids and octopi), Cnidaria (jellyfish & corals), Arthropods (insects & shrimp), and Chordata (fish ancestors). The oceans surrounding Gondwana later hosted the earliest fish, the predecessors of all vertebrates, including you and I. In the following millions of years, the first fungi inhabited the land, followed by the first tropical land plants, land insects, trees, seeds, amphibians, and reptiles. The first widespread forests created soil and hosted animal life on Gondwana, even though much of Gondwana was buried under an ice cap during the Carboniferous Ice Age. Life was flourishing on land and in the seas. Gondwana then joined with Euramerica, becoming southern Pangaea. As Pangaea Supercontinent formed a cascade of events brought life to the brink of complete annihilation. Giant mountain ranges formed as Pangaea came together, the remnants of these eroded mountains are in Eastern North America (the Appalachians), Scotland, Scandinavia, & Africa. The length of global coastlines decreased, and widespread deserts formed as the forests perished. In northern Pangaea the largest recorded volcanic eruptions occurred for about a hundred thousand years. It heralded the largest extinction of the last half billion years, The Great Dying. The survival rate was 5-10%, only the greatest survivors adapted to the Pangaean world of extremes.
Conifers, cycads & seed ferns made it through The Great Dying because they could conserve water, and when conditions became unsurvivable their seeds could wait in the soil until conditions were adequate for them to germinate. The reptiles had scales to prevent dehydration and their eggs could be laid on land, traits that allowed them to survive the desertification of Pangaea. So the reptilian survivors went on to evolve into dinosaurs, crocodiles, pterosaurs, mammals, and birds. The organisms that inherited the Earth could spread far and wide, limited only by sufficient food sources, deserts, and mountains, as no oceans barred their passage across the sprawling landmass.
Fossil evidence suggests that the first Dinosaurs evolved on the Gondwana side of Pangaea & spread across southern Pangaea and then into northern Pangaea. The oldest fossil remains of Dinosaurs are found in South America, Madagascar, Africa, and India, including Nyasasaurus and Eoraptor. These predecessors to the long neck herbivorous Sauropods like Gondwanatitan, and carnivorous Theropods like Cryolophosaurus and Australovenator evolved on Gondwana. In time the Dinosaurs took over the terrestrial world during the Age of the Reptiles. As the first Dinosaurs walked on southern Pangaea, their cousins the Pterosaurs evolved in the north and took flight eventually arriving in Gondwana while Pangaea was still whole. The oceans surrounding Pangaea were dominated by marine reptiles like Mosasaurs & Plesiosaurs. Pangaea Supercontinent began and ended as a reptile world.
Approximately 180 million years ago Pangaea broke up into the megacontinents Laurasia and Gondwana, and once again Gondwana was on its own in the southern hemisphere, remaining intact for another 30 million years. Gondwana began to break-up during the Cretaceous Period, the last period of the Age of Reptiles, but the dismantling of Gondwana was a slow process. First Africa and South America pulled apart from Madagascar, India, Antarctica & Australia, creating 2 smaller continents. Soon after, South America and Africa parted ways, and India left Madagascar behind as it swiftly moved northward to crash into Asia. Dinosaurs continued to evolve on the separating landmasses, becoming endemic (native and restricted to a certain place) to the regions they could no longer leave as new oceans and seas formed between the remnants of Pangaea. On the remnants of Gondwana carnivorous dinosaurs like Spinosaurus (Africa), Rapator (Australia), Carnotaurus (South America), and Giganotosaurus (South America) were preying on the herbivorous Titanosaurus (South America), Argentinosaurus (South America), and Antarctopelta (Antarctica & South America). In South America, the oldest known marsupial Patagorhynchus evolved alongside the largest frog ever, Beelzebufo “Devil Toad”. The demise of Gondwana allowed animals to increase in diversity, each landmass evolving predators and prey adapted to the climatic conditions they had to survive.
The last stage of the break-up of Gondwana occurred when Antarctica, Zealandia, & Australia parted ways, and at last South America pulled away from Antarctica, leaving Antarctica on the South Pole to host the third and current ice cap of the last half billion years. The ice ages that allow ice caps to exist are rare, only occurring when ice house climate conditions occur, and ice ages are rare because ice house conditions are fragile. Gondwana preserved evidence of the end of 2 ice ages before Pangaea existed, and both ended with extinctions that occurred when climate change happened faster than life could adapt. Today’s Quaternary Ice Age, which we live in and the entirety of human evolution occurred during, is rapidly moving towards its end. We can learn from Gondwana and recognize that rapid climate change is never good for apex predators, and humans are the apex predators of the present. But we have the power to change the climate, as we have already demonstrated. We could choose to use that power, that knowledge, to manage climate conditions to support our existence, the stability of the ecosystem we rely on, and create a climate that allows human civilization to prosper equitably and sustainably. The animals of past mass extinctions did not have the choices that we humans have created for ourselves, they could only adapt to climate change rather than change the climate to support the ecosystems they relied on to survive.
If you want to dive into Earth history, I highly recommend the following documentaries:
PBS NOVA Ancient Earth: Season 50 Episodes 11-15 (Birth of the Sky, Frozen, Life Rising, Inferno, & Humans...note: some of these episodes will be expiring on 12/01/23) https://www.pbs.org/show/nova/episodes/season/50/
Netflix Ancient Life on Our Planet narrated by Morgan Freeman (8 episodes): https://www.netflix.com/title/80213846
Blog Images & Videos:
Edicaran Biota https://en.wikipedia.org/wiki/Ediacaran_biota
Cretaceous continental map https://blogs.egu.eu/divisions/cl/2022/11/30/was-antarctica-glaciated-during-the-mesozoic/
Phanerozoic Global Temperature graph https://cyclesresearchinstitute.org/climate-cycles-long-term/20-phanerozoic-temperature-25-164cf099f7-2/