The major components of the air at the end of the Cretaceous were the same as those present today (Nitrogen, Oxygen, Argon, Carbon dioxide, Neon, Helium, Methane, etc). One sign of this is that some of the same creatures are alive today that survived back then. read more
The Cretaceous Period was the last and longest segment of the Mesozoic Era. It lasted approximately 79 million years, from the minor extinction event that closed the Jurassic Period about 145.5 million years ago to the Cretaceous-Paleogene (K-Pg) extinction event dated at 65.5 million years ago. read more
The other lineages of "marine reptiles" — the ichthyosaurs, plesiosaurs, and mosasaurs — also were extinct by the end of the Cretaceous, as were the flying pterosaurs, but some, like the ichthyosaurs, were probably extinct a little before the end of the Cretaceous. read more