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Age of Dinosaurs

Cretaceous North America

A map of North America during the Cretaceous PeriodA map of North America during the Cretaceous Period By the Cretaceous Period, the continent of North America had drifted away from Europe and South America, although it was still connected to Asia. North America was divided into several large islands by warm, shallow seas. The Western Interior Seaway split the continent down the middle, and joined up with what is now Hudson Bay in the north and the Gulf of Mexico in the south. The climate was warmer than today. On land, flowering plants and broadleaf trees spread among the coniferous forests that previously covered North America. Several new types of dinosaur emerged, including the hadrosaurs or the duck-bills, equipped with cheek teeth enabling them to chew their food.

Parasaurolophus, Cretaceous North AmericaParasaurolophus, Cretaceous North America
A herd of TriceratopsA herd of Triceratops

Last years

The last years of the dinosaurs produced some of the most spectacular kinds. A new group of ornithischians, the ceratopsians, or horned dinosaurs, evolved. For the last 20 million years or so of the Age of Dinosaurs, they were the most abundant large herbivores on Earth. The nine-metre (30-foot) Triceratops was typical of the group: it had a massive head with two long, pointed horns on its brow and one on its snout. Behind its skull was a massive, upward-curving sheet of bone, called a neck frill. Using its parrot-like beak, Triceratops could chomp its way through the toughest of plant foods. Only the largest, most powerful predator would have been a match for Triceratops.

Triceratops meets T.rex

Not all the giant carnivores of Cretaceous North America were tyrannosaurs. Siats, whose discovery was announced in 2013, was a relative of Allosaurus—one of the last-known members of its family. It lived and hunted in Utah during the Mid Cretaceous.

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