The Triassic-Jurassic Boundary marks a significant geological transition that occurred around 201.3 million years ago. This boundary separates the Triassic period, characterized by the dominance of reptiles and the first dinosaurs, from the Jurassic period, known for the flourishing of dinosaurs and the emergence of large herbivores and predators. This boundary is notable for a major mass extinction event, which led to the disappearance of about 75% of species on Earth. The causes of this extinction are still debated, but factors may include volcanic activity, climate change, and changes in sea levels, significantly reshaping ecosystems and paving the way for new life forms.