Laurasia Laurasia Laurasia () was the more northern of two supercontinents (the other being Gondwana) that formed part of the Pangaea supercontinent around (Mya). It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pangaea, drifting farther north after the split. The name combines the names of Laurentia, the name given to the North American craton, and Eurasia. As suggested by the geologic naming, Laurasia included most of the land masses which make up today's continents of the Northern Hemisphere, chiefly Laurentia, Baltica, Siberia, Kazakhstania, and the North China and East China cratons. Although Laurasia is known
Lungfish current distribution of modern lungfish species reflects extinction of many lineages subsequent to the breakup of Pangaea, Gondwana and Laurasia. Lungfish have historically been referred to as salamanderfish, but this term more often refers to "Lepidogalaxias salamandroides". All lungfish demonstrate an uninterrupted cartilaginous notochord and an extensively developed palatal dentition. Basal ("primitive") lungfish groups may retain marginal teeth and an ossified braincase, but derived lungfish groups, including all modern species, show a significant reduction in the marginal bones and a cartilaginous braincase. The bones of the skull roof in primitive lungfish are covered in a mineralized tissue called cosmine, but