Triassic Period In paleontology, the term Triassic (/traɪˈæsɪk/; symbol: 🝈) denotes a geologic period and a stratigraphic system that spans 50.5 million years from the end of the Permian Period 251.902 Ma (million years ago) to the beginning of the Jurassic Period 201.4 Ma. The Triassic Period is the first and shortest geologic period of the Mesozoic Era, and the seventh period of the Phanerozoic Eon. The start and the end of the Triassic Period featured major extinction events. Chronologically, the Triassic Period is divided into three epochs: (i) the Early Triassic, (ii) the Middle Triassic, and (iii) the Late Triassic. The Triassic Period began after the Permian–Triassic extinction event that much reduced the biosphere of planet Earth. The fossil record of the Triassic Period presents three categories of organisms: (i) animals that survived the Permian–Triassic extinction event, (ii) new animals that briefly flourished in the Triassic biosphere, and (iii) new animals that evolved and dominated the Mesozoic Era. Reptiles, especially archosaurs, were the chief terrestrial vertebrates during this time. A specialized group of archosaurs, called dinosaurs, first appeared in the Late Triassic but did not become dominant until the succeeding Jurassic Period. Archosaurs that became dominant in this period were primarily pseudosuchians, relatives and ancestors of modern crocodilians, while some archosaurs specialized in flight, the first time among vertebrates, becoming the pterosaurs. Therapsids, the dominant vertebrates of the preceding Permian period, saw a brief surge in diversification in the Triassic, with dicynodonts and cynodonts quickly becoming dominant, but they declined throughout the period with the majority becoming extinct by the end. However, the first stem-group mammals (mammaliamorphs), themselves a specialized subgroup of cynodonts, appeared during the Triassic and would survive the extinction event, allowing them to radiate during the Jurassic. Amphibians were primarily represented by the temnospondyls, giant aquatic predators that had survived the end-Permian extinction and saw a new burst of diversification in the Triassic, before going extinct by the end; however, early crown-group lissamphibians (including stem-group frogs, salamanders and caecilians) also became more common during the Triassic and survived the extinction event. The earliest known neopterygian fish, including early holosteans and teleosts, appeared near the beginning of the Triassic, and quickly diversified to become among the dominant groups of fish in both freshwater and marine habitats. The vast supercontinent of Pangaea dominated the globe during the Triassic, but in the latest Triassic (Rhaetian) and Early Jurassic it began to gradually rift into two separate landmasses: Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea's interior. However, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another major mass extinction, the Triassic–Jurassic extinction event, that wiped out many groups, including most pseudosuchians, and allowed dinosaurs to assume dominance in the Jurassic. The Permian-Triassic extinction event, also known as the Great Dying, was the most severe extinction event in Earth's history, occurring approximately 252 million years ago at the boundary between the Permian and Triassic periods. It's estimated that up to 96% of marine species and 70% of terrestrial vertebrate species were wiped out, according to the National Geographic. This event dramatically reshaped Earth's ecosystems and paved the way for the rise of the dinosaurs. Causes: While the exact cause is still debated, the prevailing theory points to massive volcanic eruptions in Siberia, known as the Siberian Traps, as the primary driver of the extinction. These eruptions released vast quantities of greenhouse gasses, leading to: Rapid global warming: Increased atmospheric carbon dioxide and other greenhouse gasses caused a significant rise in global temperatures, potentially by 8-10°C, according to researchgate.net. Ocean acidification and anoxia: The increased CO2 in the atmosphere also affected ocean chemistry, leading to ocean acidification and widespread ocean anoxia (lack of oxygen). Ozone layer depletion: Volcanic activity also released gases that could have depleted the ozone layer, increasing harmful UV radiation reaching the surface. Other contributing factors that have been suggested include: Asteroid impact: Some scientists have proposed that an asteroid impact may have played a role, though the evidence is still circumstantial. Coal bed fires: Large-scale fires ignited by volcanic activity could have released further greenhouse gases and pollutants. Consequences: The Permian-Triassic extinction event had profound and lasting consequences for life on Earth: Massive biodiversity loss: The extinction event eliminated a vast number of species, including many dominant groups like trilobites, early insects, and a large portion of marine invertebrates. Disrupted ecosystems: The extinction event caused major disruptions to ecosystems, both marine and terrestrial, leading to a period of instability and recovery. Rise of new species: The extinction event created ecological opportunities for new groups of organisms to diversify and flourish, including the ancestors of mammals and the early dinosaurs. The recovery from this event was a long process, taking millions of years for ecosystems to fully recover and for new dominant species to emerge.
https://www.youtube.com/watch?v=AnK4VGkeNzc
What Was Life Like During the Triassic Period?
https://www.youtube.com/watch?v=5QCKnkfwB-4
Life Got Weird After the Greatest Extinction Event
