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,
Robert Frost Trail (Massachusetts) Hadley, South Hadley, Amherst, Granby, Belchertown, Pelham, Shutesbury, Leverett, Sunderland, Wendell and Montague. The Robert Frost Trail might be divided into three general geo-ecological landscapes. Both the Holyoke Range and Mount Toby were formed 200 million years ago between the end of the Triassic period and the beginning of the Jurassic. The Holyoke Range, part of the Metacomet Ridge that extends south to Long Island Sound, are composed of basalt, an extrusive volcanic rock. This basalt ridge is the product of several massive lava flows hundreds of feet deep that welled up in faults created by the rifting apart of