Phanerozoic of Pangaea into Laurasia and Gondwana in an extinction known as the Jurassic-Cretaceous extinction. Sea levels rose, destroying fern prairies and creating shallows. Ichthyosaurs became extinct whereas sauropods, as a whole, did not; in fact, some species, like "Titanosaurus", lived until the K-T extinction. The increase in sea-levels opened up the Atlantic sea way which would continue to get larger over time. The divided world would give opportunity for the diversification of new dinosaurs. The Cretaceous is the longest period in the Mesozoic, spans from 145 million to 66 million years ago, and is divided into two epochs: Early Cretaceous,
Partridge Island (Nova Scotia) geological period between 208 and 220 million years ago, rivers swollen by intense rains carried coarse sediments (now sedimentary rocks) from nearby highlands into the Fundy Basin. Other deposits came from wind-blown sand dunes. Later, large lakes formed on the central part of the basin depositing finer sediments up to 1,000 metres thick and, as they dried up periodically, they left behind salt and gypsum deposits. The red sedimentary sandstone base of Partridge Island dates from the late Triassic period. The covering layer of dark basalt was formed from magma and lava eruptions in the Jurassic period between 175 and