We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.
Biology

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

What Was the Cretaceous Period?

Michael Anissimov
By
Updated: May 21, 2024
Views: 9,517
Share

The Cretaceous period is the third of three periods of the Mesozoic Era, the "middle era" of complex multicellular life on the Earth. The Cretaceous period extended from the end of the Jurassic period, about 145 million years ago, to approximately 65 million years ago, when the Cretaceous–Tertiary extinction event wiped out most of the dinosaurs. The ancestors of modern-day birds are dinosaurs that survived.

The Cretaceous period was an extremely important period for life on Earth. The diversity and size of dinosaurs was at its height. Insects began to diversify as well. The maniraptora clade evolved, a transition clade between dinosaurs and birds. Pterosaurs continued to rule the sky, specializing in an ecological niche similar to modern-day birds for over 150 million years.

The Cretaceous oceans started off being dominated by plesiosaurs and pliosaurs, as they had for most of the Mesozoic era. But by the mid-Cretaceous period they started to decline, and modern-day sharks, rays, and certain fish species become more abundant. Mosasaurs, something like a cross between a snake and a monitor lizard which could swim, were the leading marine predator by the end of the Cretaceous period. The largest of these grew to 17 m.

At the opening of the Cretaceous period, there was a cool period, a continuation of a trend that was occurring throughout the Jurassic. The temperatures at that point were still hotter than today, but more similar than most other Mesozoic climates. By the middle of the Cretaceous period, volcanic activity picked up, throwing carbon dioxide into the air and increasing the temperature once again. In the oceans, huge ridges widened, being filled by mantle plumes from below, creating vast, shallow seas.

Due to a slow temperature gradient from the equator to the poles, there was less upwelling in the world's oceans, making them substantially warmer and more stagnant than those of today. For geologically short periods, the tropical oceans may have reaches temperatures as high as 42 °C (107 °F), averaging 37 °C (98.6 °F). In the end of the Cretaceous period, sea levels dropped level than any previous time in the Mesozoic period.

The Cretaceous was the golden age of giant sauropods, including Brachiosaurus, Seismosaurus, and Supersaurus. The longest among these were 40 meters (130 ft), in length, weighing 100 tons or so, with a possible species, Bruhathkayosaurus, reaching as much as 240 tons. At such sizes, they would have approached the maximum weight a terrestrial animal can be and still support its own weight.

The Cretaceous period was brought to a close by a giant meteor. This is evidenced by iridium deposits worldwide. Iridium is very rare in the Earth's crust, but plentiful in comets and asteroids.

Share
All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Michael Anissimov
By Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology, astronomy, chemistry, and futurism to his articles. An avid blogger, Michael is deeply passionate about stem cell research, regenerative medicine, and life extension therapies. His professional experience includes work with the Methuselah Foundation, Singularity Institute for Artificial Intelligence, and Lifeboat Foundation, further showcasing his commitment to scientific advancement.
Discussion Comments
Michael Anissimov
Michael Anissimov
Michael Anissimov is a dedicated All The Science contributor and brings his expertise in paleontology, physics, biology...
Learn more
Share
https://www.allthescience.org/what-was-the-cretaceous-period.htm
Copy this link
All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.