The Triassic Period

The Triassic Period- First Dinosaurs

In the last article, we introduced the Mesozoic era. Now it is time to fully examine the Triassic period when the ecological situation changed completely. Life recovered from the mass extinction, bringing new adapted species to a new era.

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Marine Life of the Triassic period

The first major change in the Triassic marine life happened on a micro-level. Before the Great Dying the red algae dominated in the sea, however many of them suffered from extinction. In the Triassic, the algae containing more complex structures from secondary endosymbiosis took over. Due to that change, the rest of the marine life also recovered a bit differently. New kinds of corals created reefs, still smaller than the Devonian ones. The marine mollusks- ammonites- managed to survive extinction and also recovered. When it comes to vertebrates, species of fishes were very similar to one another. That was because not many kinds survived the Great Dying. The Triassic, however, brings a new kind of sea-dominant group. Marine reptiles started to develop very fast, and soon ancestors of crocodiles and lizards spread in all the oceans.

During the Triassic period marine reptiles dominated the seas
During the Triassic marine reptiles dominated the seas
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The First Dinosaurs

Fauna that survived was slowly recovering from the extinction. The amphibians did best during the Great Dying, so the period started with their dominance. There were not many amniotes left, however, cynodonts with important mammal traits managed to recover. At the end of the period, even modern mammals evolved. Finally, a new group started to emerge and it was about to dominate the ecosystems in the next period. It comes with no surprise, that we are talking about dinosaurs. However, to be exact the group is called Ornithodira and it includes also pterosaurs. The first, primitive, but similar relatives are probably Marasuchus from the Middle Triassic. However, the ‘full’ dinosaurs appeared in the Late Triassic. Amongst them, we can find Eoraptors, small predators, probably the ancestors of all other dinosaurs. Other important reptile clades included the first crocodylians, relatives of archosaurs, and the first turtles.

First dinosaurs evolved from reptiles
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Changes in Earth

The climate on the continent was generally hot and dry, with many seasons and monsoon regions. However, in the Late Triassic, the Carnival Pluvant Event caused a major climate change. Due to the rise of temperature and humidity, rainforests and tropical ecosystems started to emerge. For the most time, the polar region wasn’t so polar, there was probably no glaciation. However, in those regions the temperature was still high, there was also more water, which provided nice conditions for many organisms. When it comes to the continents, the most interesting thing happened in the Late Triassic. The supercontinent Pangea started breaking up, creating many new, not connected ecosystems. The official breakup is marked with separation of today’s Morroco from the terrain of today’s New Jersey, US. Another important geological event was the creation of the famous Scandinavian peneplains.

Continents during the Triassic period
Continents during the Triassic period
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The end of the Triassic

We said, that first dinosaurs appeared in the Triassic. However, there was one more step needed for them to dominate. That step was the extinction of other dominant groups and it comes with the end of the period. It might have been a gradual change in dominance or a massive volcanic eruption. Some studies even suggest an asteroid impact, which is quite ironic. The Triassic-Jurassic extinction event wipes out conodonts and first mammals. Of course, dinosaurs and other reptiles also suffered, however they managed to recover and fill the ecological niches quicker than their opponents. Plants also suffered and Jurassic brings new kinds that evolved from the remains. The corals were destroyed once again, causing a snowball effect on all species living on the reefs. However, not every organism suffered. Plankton was quite adapted, fish also did well after they had a development boost in Middle Triassic.

Triassic Period Evidence

The evidence from the Triassic period tells us a lot about its plants. Huge ferns and horsetails grew, the seed plants started to dominate. In the north conifers ruled, the seed ferns dominated the south. There are of course fossils of corals and ammonites from sea ecosystems. The Sauropterygia was a group of marine reptiles, many fossils of them were found, the same with first plesiosaurs. There is also evidence prooving the presence of Dipnoi (a kind of fish), and the Temnospondyls amphibians in freshwaters. Other fossils include the whole scale of development from early dinosaur ancestors, to the Eoraptor. We can also find first turtle shells and first animals with adaptation to the nocturnal lifestyle.

Body fossil of an early dinosaur
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Read the previous in the series: An Introduction To The Mesozoic Era

Author’s Message

I hope that the article helped you learn about the wonders of the Triassic. If you enjoyed it, please share it with family and friends. In the next one, we will proceed to talk about the Jurrasic, so stay tuned. If you wish to contact me, use the ‘Contact Us’ form or write an email. You can find my address in the team’s section of the page.

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