Earth’s history spans a vast timeline, marked by shifts in continents, climates, and life. Examining specific geological periods offers insights into our planet’s transformations. Approximately 240 million years ago, during the Triassic Period, Earth looked vastly different than today. This era shaped life forms and geological features for millennia.
The Supercontinent Pangaea
Around 240 million years ago, Earth’s landmasses united into a single supercontinent called Pangaea. This landmass covered about one-quarter of the planet’s surface, stretching from near the North Pole to the South Pole. Pangaea consisted of two main sections: Laurasia to the north (future North America and Eurasia), and Gondwana to the south (future South America, Africa, India, Australia, and Antarctica).
This continental configuration influenced global geography. A vast global ocean, Panthalassa, surrounded Pangaea, stretching from pole to pole. Projecting westward into Pangaea, between Laurasia and Gondwana, was the Tethys Ocean, roughly where the Mediterranean Sea is today. This ancient seaway shaped the supercontinent’s climate by bringing humid air inland.
Global Climate and Landscapes
The climate across Pangaea 240 million years ago was hot and arid, especially in the interior. The supercontinent’s size meant central areas were far from oceanic influence, leading to extreme temperatures and widespread deserts. These deserts experienced scorching days and frigid nights. Evidence of this arid environment includes red sandstones, shales, and lithified dune deposits.
Despite the overall dryness, coastal regions, particularly near the Tethys Ocean, experienced strong seasonal monsoons. Coal-rich sediments and large amphibians in high northern and southern latitudes suggest these areas were wetter. The Triassic climate, influenced by Pangaea’s configuration, was more homogeneous globally than today, lacking polar ice caps and having less extreme temperature differences between the equator and poles.
Dominant Life Forms
Earth 240 million years ago was recovering from a mass extinction at the end of the Permian Period, which had wiped out many marine and terrestrial species. This recovery saw the rise of reptiles, which would dominate the Mesozoic Era. Early dinosaurs began to appear in the fossil record around this time. These initial dinosaurs were often small, bipedal creatures, evolving from archosaurs.
Other reptile groups were also prominent. Synapsids, often called mammal-like reptiles, were widespread, with creatures like the herbivorous Lystrosaurus common in the early Triassic. Though still significant, synapsids were being outcompeted by diversifying archosaurs. In the vast Tethys Ocean, marine reptiles like ichthyosaurs (dolphin-like bodies adapted for rapid swimming) and long-necked plesiosaurs became significant predators.
Plant life lacked flowering plants, resulting in a landscape dominated by greens and browns. Conifers, cycads, and ferns were the prevailing vegetation. Conifer forests were common, especially in northern regions, while seed ferns like Dicroidium dominated southern Gondwana. Horsetails were also present, providing an important food source for herbivorous animals.