Dinosaurs of the Cretaceous

Dinosaurs of the Cretaceous — page 1 — LAURASIA Interior Equator ONDWAN INDIAN OCEAN 145 mya 105 mya 145 Millions of years ago mya EARLY CRETACEOUS Temperatures become cooler 138 mya Temperatures rise Sea surface temperatures may resulting in snowfall at high and remain high due to have been 31 °F 17 °C altitudes intense volcanic activity warmer than today The Cretaceous Period During this period the supercontinents of Laurasia and Gondwana continued to break up into present day continents although their positions were very different at the time The Atlantic and Indian Oceans were newly formed and the Tethys Sea continued to narrow As sea levels rose shallow seas called the Western Interior Seaway appeared across North America and Europe The period ended with the Cretaceous Paleogene K Pg extinction

Dinosaurs of the Cretaceous — page 2 — Asi Interior Seaway tralia 90 mya 65 mya 100 LATE CRETACEOUS 91 mya Lack of oxygen in 65 mya The Cretaceous Paleogene K Pg extinction oceans causes extinction of event killed off as much as 75 of plant and animal ichthyosaurs species on Earth including all dinosaurs LIFE DURING THE CRETACEOUS PERIOD On land mammals were relatively small and still evolving The dinosaurs remained the dominant species Huge carnivores such as Tyrannosaurus rex and Giganotosaurus appeared Giant sauropods called titanosaurs appeared in the southern continents Herd dwelling ornithischians such as Iguanodon spread everywhere Vast herds of horned dinosaurs such as An Austroraptor Triceratops lived in the northern continents The feathered approaches a group dinosaur group maniraptora appeared which was a transition of titanosaurs between dinosaurs and birds Pterosaurs were common Some called Saltasauruses grew to enormous sizes but faced growing competition from the from South America evolving bird population Marine reptiles included ichthyosaurs 80 million years ago plesiosaurs and

Dinosaurs of the Cretaceous — page 3 — Cretaceous Period 130 mya Europe Concavenator One of the strangest fossil finds in recent years is that of a medium sized theropod called Concavenator Its name means Cuenca hunter after the place in Spain where it was found Concavenator had a strange hump on its back above its hips Scientists are unsure of its purpose It may have been a area that stored fat for lean times when prey animals were few and far between Feather quills grew from its forearms The quills may have been used for display

Dinosaurs of the Cretaceous — page 4 — A Polacanthus 1 is taken by surprise by a Concavenator 2 in this scene from early Cretaceous Europe Pelecanimimuses 3 and Hypsilophodons 4 who have been drinking at a spring flee in terror during mating rituals The early spiked plant eating Polacanthus also lived in Europe at that time Its thick armored plates and spikes were an effective defense against predators Smaller dinosaurs such as the ornithomimosaur Pelecanimimus and the ornithopod Hypsilophodon were also present Concavenator grew to about 19 7 feet 6 m long and weighed about 2 tons 1 8

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