In the last article, we started discussing the Cenozoic Era. Now, it is time we move on and talk about its first period- The Paleogene period.

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Beginning of the Era of Mammals

As we discussed before, the mass extinction event wiped out the dinosaurs. As a result, many ecological niches emptied out. In the Paleogene mammals start diversifying fast, creating precursors of most modern species. Similarly to dinosaurs, they started adapting to various ecological niches. Some started growing taller, co-evolving with plants. Others started to hide from predators and therefore shrinking.

Millions of years after leaving the water environment, marine and freshwater mammals also developed. They were the ancestors of modern cetaceans. Soon, first were about to develop the ability of gliding, which will turn to active flight. Finally, many species started to live on the trees. Adaptations to that lifestyle made them develop into primates- a group we also belong to. Among other animal groups, amphibians and reptiles were slowly recovering. The only remaining group of dinosaurs-birds- also started to develop fast, due to the absence of pterosaurs.

In the Paleogene the Era of Mammals started
In the Paleogene, the Era of Mammals started
Image Courtesy

The First Grasses

In the Paleogene period, one major process on the plant front started. Due to the cooling in the Late Paleogene, there was a huge flower plant development. Amongst them, first grasses and herbs appeared. They created a new environment for animals, which started to adapt to new conditions. Small rodents started feeding on seeds and hiding in grasses from predators. Grasses were also a hospitable environment for insects, ringed worms, and other small animals.

They also began to spread fast, due to numerous seeds and reasonable needs. Soon, they partially took place of the rainforests because the cooling trend continued. As for colder regions, conifers managed to conquer the mountains. Resistant to low temperatures, wind, and lack of water pygmy conifers settled in the high regions and survived there until today.

Fossil of Paleogene period grasses
Fossil of Paleogene period grasses
Image Courtesy

Changes in Earth

The Mesozoic had great conditions for dinosaurs, however, they also change a lot in the Cenozoic Era. There were a huge cooling and drying trend, which continued to the next period. It led to the development of grasses and reducing rainforests. Despite that, a recent study suggested that the average temperature was still about 12 degrees Celsius higher than today!

On the continental front, looking at the map we start to see some familiar shapes. India continued drifting north from Africa, not yet meeting with Asia. Both Americas drifted west and started moving towards each other. Australia separated from Antarctica and was drifting to the east. Africa was slowly moving north, towards Europe, to later form the Mediterranean sea. Inland seas in both Americas disappeared, the Atlantic ocean, on the other hand, was quickly growing wider.

Continents during the Paleogene Period and the Era of Mammals
Continents during the Paleogene
Image Courtesy

Evidence of the Paleogene Period

Speaking of the Cenozoic Era we will more often than earlier find pieces of evidence that are still alive. For example, Artemisia (wormwood) is quite a common herb from North America. It made its first appearance during the blossom of grasses in the Paleogene period. There are still, of course, some primal, extinct grasses that preserved only as fossils. We can also find standard pieces of minerals found both in America and Africa, or Antarctica and Australia, proving they were all once one landmass.

Despite that, there are also many fossils of ancestors of primates. Looking at some old species, that did not change much, we can also track the evolutionary process ourselves. For example, by comparing invertebrates and vertebrates. Important pieces of direct evidence include also marine mammals. The Basilosaurus was an ancestor of the modern whale, living in the middle of the period.

The Paleogene Period 1
Fossil of the Basilosaurus
Image Courtesy: National Geographic

Read the previous in the series: Introduction to the Cenozoic Era.

Author’s message

I hope that the article helped you learn about the Paleogene period. If you enjoyed it, please share it with family and friends. In the next one, we will move on to the next period of the Era of Mammals- the Neogene. Until then, feel free to contact me using the form below or writing an email. You can find my address in the team’s section of the page.

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[…] the previous article, we discussed the first period of the Cenozoic. Now it is time we move on to the period before our […]

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