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 from 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.

What are Some Paleogene Organisms?

Michael Anissimov
By
Updated Feb 07, 2024
Our promise to you
AllTheScience is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

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.

Editorial Standards

At AllTheScience, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The Paleogene Period is a geologic period that stretches from 65.5 million years ago, when the dinosaurs were blasted into extinction by an asteroid, to 23 million years ago, when the period was concluded with an extended episode of global cooling. Compared to the present day, the Palogene was a warm time, and as such, is sometimes called "a continuation of the Mesozoic, but with mammals."

Just as during the Mesozoic, during the Paleogene, the world was warm, with no polar ice caps, and dense forests extended further north and south, to places like Wyoming. The Paleogene had high sea levels, but not as high as during the Cretaceous before it, and except for the flooding of large portions of central Eurasia, the configuration of the continents was pretty much the same as it is today.

The Paleogene was characterized by the rapid diversification of mammals and the filling of numerous niches left open by the extinction of all non-avian dinosaurs, pterosaurs (flying reptiles), and large marine reptiles (plesiosaurs, mosasaurs, etc.) However, unlike the gigantic dinosaurs that came before them, the land mammals of the early Paleogene were relatively tiny, with none larger than a bear, and most much smaller, about the size of cats. Larger mammals, like the ancestors of rhinoceroses, evolved in the middle of the period.

Many of the groups that dominated the Paleogene are extinct today. The cougar-like animal Mesonychia is thought to have been a leading scavenger or predator of the early Palogene. In the early part of the Paleogene, cats, pigs, and whales evolved. In the middle of the Paleogene, bats, the ancestors of elephants, and Eohippus, the first horse, evolved. Towards the end of the period, rodents and the first primates evolved, along with condylarths, which are considered the ancestors of modern hoofed herbivores. Various early spinoffs of animals like the horse, like Propalaeotherium, whose evolutionary lines would die out without leaving any descendants, evolved during this period.

In the skies, birds were busy at work taking over the niche left empty by the death of the pterosaurs. Birds evolved into a variety of fantastic colors, shapes, and sizes, by the end of the period achieving a level of diversity similar to today's. In the oceans, with the death of the ammonites, the predominant mollusk became squid, while sharks grew in diversity and numbers to take up the niches left empty by the demise of large marine reptiles. These were soon joined by whales, which took tens of millions of years to achieve their present size.

AllTheScience 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 is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Discussion Comments

Michael Anissimov

Michael Anissimov

Michael is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology...

Read more
AllTheScience, in your inbox

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

AllTheScience, in your inbox

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