South America



South America was covered in the densest rainforest of all the continents during the early Triassic. It was very warm, 29 degrees. Not much is known of the fauna, although some cynodonts and dicynodonts are known. †Lystrosaurus are the best known dicynodonts. Although gorgonopsids were initially absent in South America, African species migrated into South America, and became the continents top predator. There is a section at the edge of Argentina which is clear of rainforest, instead being a desert. There is a large lagoon, which beautifully preserved many Triassic species. Many acanthodians have been found (one of the species being an eel like form, †Moramimus), as well as large lungfish, coelacanths, and palaeonisciformes. There have also been many fossils of mesosaurs, showing that the lagoon was possibly used as a breeding site. As the Triassic went on, the rainforests began to shrink. Then, during the Norian Hothouse Event, the rainforests shrunk by 65%, being replaced by desert. The hottest desert in the world at the time was the Amataca Desert in Argentina. Previously jungle dwelling animals now adapted for a dry environment. †Cucumipellis, a desert dwelling gorgonopsid, became slightly large and evolved wrinkly and bumpy skin, like a cucumber. The southern cape was so badly damaged by the NHE, that it was devoid of all life for a few kilometers. Even the offshore communities were destroyed, and absent of life. While most of the world managed to recover their rainforests after the NHE, South America remained the same right through the Triassic.

During the early Jurassic, life slowly began to return back to the southern cape. However, Pangea began to split apart. The remaining rainforests began to disappear as well, being replaced by horsetail prairies. As South America was torn away from Africa, the southern cape suffered major faunal loss again. Because the Atlantic was formed, it brought new life to Brazil, which was rich in tree ferns and ferns. Dicynodonts were the dominant herbivores of the landscape, specifically †Novacodon. The flora-heavy areas provided cover for the large gorgonopsids to hide and hunt. The forest also had a great diversity of herbivorous, insectivorous, and carnivorous Weigeltisauriformes. Tritylodont cynodonts became bigger, and were also gorgonopsid prey. This habitat as lush and warm. As South America moved further away, this created a mountain range in the middle of Argentina, and it is believed that a flood basalt was also made in Uruguay. During the mid Jurassic, a massive eruption devastated all of eastern South America, destroying the unique tree fern habitats, and wiping out most life forms in the area. During the late Jurassic, woodland habitats stretched from northern South America, and scattered into southeastern Brazil. This had a relatively warm climate, over 28 degrees, and anapsid millerosaurs are found in great diversity, some evolving armour to defend themselves against woodland gorgonopsids.

During the Cretaceous things got colder, but the Amataca Desert got only hotter. This drove gorgonopsids out completely, being replaced by archosaurs. The gorgonopsids retreated up into the mountains of mid Argentina. As the climate got colder, snow fell, so gorgonopsids clung on where there was little competition. However, it soon got too cold for the South American gorgonopsids, who, with nowhere to go, died out, making it the earliest mass extinction of Cretaceous gorgonopsids. Gorgonopsids wouldn't start to go extinct for another twenty million years elsewhere. At the same time, lagoonal environments started to disappear, and South American mesosaurs went extinct. Nevertheless many animals were still extant. During each cooling cycle, the Amataca Desert got hotter and the woodlands spread, while in every warming cycle, the Amataca cooled down slightly and the woodlands were replaced by fern prairies. However, when ice caps formed in the Campanian, the Amataca's temperature wildly increased and the climate became more unstable, and the woodlands spread out into Argentina. At the end of the Campanian glaciation, the Amataca cooled down and the woodlands retreated back to their original spots.

However the biggest change was in the Maastrichtian. The Amataca didn't heat up as much, and the woodlands became temperate forests that spread out into Argentina. The ice sheet that covered Antarctica at the time reached into Argentina's tip. Several islands became locked in ice, and everyday the glaciers moved further into Argentina. This ice age had a profound effect on the oceans. Currents that used to run past Antarctica and South America were slowed down, which caused the oceans to heat up briefly. In southern Argentina, animals had to leave. The weigeltisaurs left as it got too cold. Soon the Chiropteramimids from the mountains migrated to southern Argentina and took over the same niche that weigeiltosaurs used to fill. Dicynodonts were also forced to move out. Not many fossils are known, so it remains a mystery as to what exactly lived there, apart from the Chiropteramimids. The weigeltisaurs moved into the Amataca Desert. The temperate forest in southern Argentina became an polar forest, and it snowed everyday. This faunal and geographical arrangement lasted into the early Cenozoic. More to be added soon...