What was the period of chalk?

2 Cretaceous periods have been extended since the end of the Jurassic period, about 145 million years ago, to approximately 65 million years, when most dinosaurs smoked chrisal and fusion. The ancestors of modern birds are dinosaurs who survived.

The challenge period was an extremely important period for life on Earth. The variety and size of the dinosaurs was at its height. Insects also began to diversify. Clade's Maniraptor has evolved, transient between dinosaurs and birds. The Pterosaurs continued to rule the sky and specialized in an ecological niche similar to modern birds for more than 150 million years. But until half of the circuit, they began to decline and modern-Žraloci, rays and some fish species became more abundant. Mosasaur, something like a hybrid between a snake and a monitor lizard that could swim, were the front sea predator until the end of the chart. The largest of them rose to 17 m.

To the cold period, the continuation of the trend that occurred in Jurassic. The temperatures at this point were becoming more warmer than today, but more similar to most of the other mesozoic climate. In the middle of the chalk, volcanic activity rose, threw carbon dioxide into the air and raised the temperature again. In the oceans, huge ridges spread and were filled with cloak clouds from below and formed a huge, shallow sea.

Due to the slow temperature gradient from the equator to the poles, there was a lower formation in the oceans in the world, which is produced hotter and stagnant than today. For geologically short periods, tropical oceans can reach temperatures of up to 42 ° C (107 ° F), on average 37 ° C (98.6 ° F). At the end of the chalk period, sea levels dropped than any previous time in the mesozoic period.

chalk was the golden age of giant sauropods, including brachiosaurus, seismosaurus and supersaurus. The longest of them was 40 meters (130 ft), in length, weighing about 100 tons, with a possible type, Bruhtkayosaurus, reaching up to 240 tons. In such sizes, they would approach the maximum weight that can be a earthly animal and still support its own weight.

Cretaceous time was approached to close the huge meteor. This is evidenced by iridium deposits around the world. Iridium is very rare in the Earth's crust, but abundant in comets and asteroids.