North America



This continent is similar looking to what we know, but it's history is very different. During the early Triassic, it was connected to Pangea. Because the world was covered in dense rainforests, it is especially odd that the central United States was mainly an enormous desert. In Mexico, it was slightly wetter, and floodplains of vegetation stretched out for miles. Despite this it was a very humid environment, mostly dominated by ferns, horsetails, and kavilyphyta. Here is were we find dicynodonts of all kinds, along with many cynodonts. There were no great land predators at that time, instead there were large temnospondylids that stalked the rivers and hunted dicynodonts. Average temperature was about 29 degrees.

In most of the United States the land was covered in dense rainforests, and with it were strange animals found nowhere else. The temperature was lower than in Mexico, about 27 degrees, but was much more humid. There are much higher concentrations of animals here than in any other part of the United States. The rainforests were thought to have covered all of the Western and Eastern Seaboard, as well as the borders of Canada and Mexico. From Canada the rainforests extended and covered the lower half of Canada, but the upper half was mostly floodplain. Like the floodplain of Mexico those in Canada had similar fauna, but had different flora and temperature. Overall the average temperature on the Canadian floodplains was 23 degrees but was more humid than Mexico or the United States. The rainforests broke into Alaska, but they also had slightly cooler temperatures, about 24 degrees. A set of islands were off the coast of Alaska, and they were also covered in rainforests. The rainforests are also thought to have covered Greenland. Rivers of various sorts spread out from Mexico and into North America and even Canada. The rivers were the only source of water in the mid desert. The desert was enormous, and had very different climate, fauna, and flora. While it did have the rivers it was incredibly dry. It had very little humidity, but had by far much higher temperatures and almost no seasons. The average temperature was 32 degrees, and rarely dipped below that. The plants were much tougher, and drier than elsewhere to adapt to the dry environment. They had very little nutrients, and grew very, very slowly, relying on the very little rainfall the desert provides. Here dicynodonts did not live, but the environment favoured mostly reptiles. The main herbivores of the desert were pareiasaurs. They were ectothermic, and could survive months without food or water. Arthropods were very common, and some grew to large sizes, for example a scorpion was found there, nearly 12 centimeters long. The only other land animals were cynodonts, which were highly adaptable and could survive the harsh habitat, and in addition there were various lizard like millerosaurs, including one hypercarnivorous millerosaur that had a similar size and visage to the komodo dragon, constituting it as the top predator of the deserts. Archosaurs were also present. The rivers had a some fish, small temnospondyls, and xenacanthia.

The border between North America and Europe was characterized by a long mountain range, which had a strange landscape, somewhere between a rainforest or temperate forest. Lastly the coastlines were very similar to the coastlines of southern California in our world. The sea was very warm, and because warm currents sped up from the southwestern United States and collided with slightly cooler currents from Alaska, storms were common on this side of the Panthalassa, though their severity was likely low.

As the Triassic grew on, the rainforests ended up covering Mexico and some of Canada, and slightly shrunk the desert. However, by 210 million years ago, during the Norian Hothouse Event (NHE), things heated up drastically, due to volcanic activity in Greenland, the temperature rising up to 30 degrees. This caused the deserts to expand, pushing out the rainforests, though remnants hung on in Alaska, the Euro-American Mountain Range, and Mexico. This caused pareiasaurs to diversify. Once the NHE started to die down, the rainforests came back and the North American pareiasaurs became extinct. At the end of the Triassic, the Greenland volcanic areas became active again, causing the rainforests to shrink, though it was less severe than the NHE.

Deserts and rainforests about evenly covered North America during the early Jurassic. Then, during the early Toarcian, Pangea began to split. As it did, the Euro-American Mountain Range became volcanic, and had a profound effect on the life living on both North America and Europe. When it was done splitting, a chain of island lied off the coast of the eastern United States, and Greenland was nearly separated, and a thin slice of the Atlantic lied between North America and the other continents. North America was finally isolated, and so it began to develop some more unique fauna and flora. The rainforests gave way to open plains, floodplains, mixed in with the occasional desert. Temperatures lowered to 26.5 degrees. Dicynodonts diversified some growing gigantic sizes, like †Salixadon, a 4 metre high herbivorous and insectivorous long necked dicynodont that used its long tusks and enormously long sticky tongue to grab a hold of vegetation and insects. By the late Jurassic, temperate forests began to grow, mostly further north. While some of Canada was covered in plains, temperature forests grew. Here temperatures lowered dramatically, and were on average only 8 degrees. For the first time there were seasons, during the warm season temperatures were only 16 degrees, but by the cold season, it was -10 degrees, and snow fell in huge numbers. Here there were more unique fauna. Cynodonts roamed across the temperate lands. Some evolved vole like forms, and some were large hunters and scavengers, reminiscent of wolverines. Some archosaurs were also found up there. Advanced dicynodonts also thrived, with the mustellimimids. Some snow dwelling temnospondyls are also known. This was the first time anywhere that snow had fell enough to force an evolutionary change in the fauna that lived in it. But this all changed when a sudden warming cycle of the Earth destroyed the temperate forests, and with it all of its unique fauna.

The warming cycle lasted into the early Cretaceous. During this time deserts grew slightly and so did the floodplains, and temperatures were consistently 28 degrees. Archosaurs diversified substantially, and so did the dicynodonts. When the climate changed again with a cooling cycle in the Valanginian, temperatures fell again, the temperate snowy forests returned to the north. What processed was two more cooling and warming cycles, each time the ice caps grew larger and larger. By the Campanian the ice caps were stretching into Canada. Now the forests could get to -30 degrees. The surviving mustellimimids, now mostly hydramimids, migrated back north. One particular hydramimid, †Anurocheirus, actually migrated from the Arctic of Russia to the Arctic of North America, inhabiting streams. In addition the pinnedonts, descendants of aquatic dicynodonts, went into large arctic rivers and lakes in the Arctic of Canada, Asia, and Europe, another similar group of wolverine like cynodonts to the one off genus in the Jurassic evolved. Because the ice caps formed, sea levels dropped, and so Beringia was formed. This allowed Asian and North American species to exchange. In the rest of North America, the land was a mix of conifer forests and open prairies. The archosaurs primarily dominated Mexico and the United States. Following the end of the Campanian glaciation, the continent was nearly split in half by an inland sea. The sea started up in the North Pole, went down through Alberta, and into Montana, and ended in Texas, just before it could merge with the Gulf of Mexico. The sea was pretty deep, up to 2 kilometers deep, and filled with various chondrichthyes, osteichthyes, as well has some ichthyosaurs and other marine reptiles.

The warming cycle was short lived, as when the Maastrichtian started a second, even more severe ice age began. This locked up more water, and so ended up destroying the inland sea. The North American landscape reverted back to it's state during the Campanian, and persisted into the early Cenozoic. More to be added soon...