Glossary

**Gondwana** is the ancient large landmass—variously termed a supercontinent or superterrane—that incorporated present-day South America, Africa, Arabia, Madagascar, India, Australia, Antarctica, and the micro-continent of Zealandia. It was fully assembled by the late Neoproterozoic to early Cambrian (approximately 600–500 Ma) through a series of continental collisions collectively known as the Pan-African orogenies, during which multiple Precambrian cratons were welded together along extensive suture belts. In the late Paleozoic, Gondwana joined with the northern landmass Laurasia to form the supercontinent Pangaea, constituting its southern half. Gondwana's breakup commenced in the Early Jurassic (approximately 180 Ma), triggered in part by the eruption of the Karoo-Ferrar Large Igneous Province, and proceeded in stages through the Cretaceous and into the Cenozoic, progressively yielding the modern southern continents and the Indian subcontinent. The existence and subsequent fragmentation of Gondwana are supported by multiple independent lines of evidence, including shared fossil assemblages (notably the *Glossopteris* flora), Permo-Carboniferous glacial deposits (tillites), matching geological structures across now-separated continents, paleomagnetic data, and marine magnetic anomaly records from the southern ocean floors. Gondwana's dispersal fundamentally shaped global ocean circulation, climate patterns, and the biogeographic evolution of southern hemisphere biota.

**Laurasia** is the northern landmass that formed part of the Pangaea supercontinent from approximately 335 million years ago (Early Carboniferous) and separated from the southern landmass Gondwana around 175 million years ago (Middle Jurassic) during Pangaea's breakup. It comprised the continental crust that now constitutes North America, Europe, Scandinavia, Siberia, Kazakhstan, and China. The **Tethys Sea** lay between Laurasia and Gondwana, acting as a major oceanic barrier that drove independent evolutionary trajectories on either side. Laurasia itself did not remain a unified landmass: internal fragmentation progressed through the Late Cretaceous and Paleogene, culminating in the opening of the Norwegian Sea around 56 million years ago, which finally separated North America–Greenland from Eurasia. In paleontology, Laurasia served as the primary arena for the diversification of iconic Late Cretaceous dinosaur groups—including tyrannosaurids, ceratopsids, dromaeosaurids, and hadrosaurids—whose distributions were shaped by intermittent land connections such as the Bering Strait land bridge linking Asia and North America. The concept of Laurasia was proposed by South African geologist Alexander du Toit in 1937, modifying Alfred Wegener's single-supercontinent hypothesis by envisioning two primordial landmasses separated by the Tethys.

Pangaea was a supercontinent that incorporated nearly all of Earth's landmasses into a single continuous body of land. It existed as a fully assembled supercontinent for approximately 160 million years, from its coalescence around 335 million years ago (Ma) during the Early Carboniferous to the onset of its fragmentation around 175 Ma in the Middle Jurassic. Pangaea formed through the progressive collision and suturing of three major pre-existing continental units—Gondwana, Euramerica (Laurussia), and Siberia—during the late Paleozoic, culminating in its maximum packing by approximately 250 Ma in the Late Permian. The supercontinent was surrounded by a single global ocean known as Panthalassa, while a large embayment called the Tethys Sea separated the eastern portions of its northern and southern landmasses. Because of Pangaea's immense size and the resulting distance of interior regions from moderating oceanic influences, its climate was characterized by extreme continentality: vast arid deserts dominated the interior, seasonal temperature swings were severe, and climate models indicate the establishment of a powerful "megamonsoonal" circulation pattern that drove intense wet-dry cycles along coastal margins. Pangaea's existence had profound consequences for the evolution and distribution of life on Earth. During the Triassic, terrestrial vertebrates—including early dinosaurs—could disperse across nearly the entire globe over continuous land without oceanic barriers, producing cosmopolitan faunas. The supercontinent's subsequent breakup, initially splitting into northern Laurasia and southern Gondwana during the Jurassic, progressively isolated populations on diverging landmasses and drove the independent evolutionary radiations that generated much of the biodiversity observed in the later Mesozoic and Cenozoic eras.