Geoscience Reference
In-Depth Information
As the Atlantic Ocean opened, rift valleys, or basins, formed along the margins of the eastern seaboard and today pre-
serve a remarkable fossil record of the rise of the dinosaurs.
Despite their formidable arsenals, rauisuchids, along with phytosaurs and aetosaurs, disappeared by the end
of the Triassic and were replaced by the early dinosaurs, including a birdlike species that left footprints in the
Fundy sandstones—possibly the carnivorous theropod Coelophysis, a member of the coelurosaurs, or hollow-
boned reptiles. These were slender, fleet-footed bipeds with pointed heads, well armed with teeth serrated like
steak knives. They probably hunted in packs. But there were also larger tracks made by plant-eating prosauro-
pods, long-necked dinosaurs with small heads, which were the forerunners of the giant sauropods such as
Brontosaurus of the Late Jurassic, the largest land animal that ever trod the Earth.
