Paleogene

Definition

The Paleogene is a geologic period that spans from about 66 to 23 million years ago, following the end of the Cretaceous period and preceding the Neogene period. It is characterized by significant evolutionary developments, particularly in mammals and birds, as they diversified after the extinction event that marked the end of the dinosaurs. This period played a crucial role in shaping modern terrestrial environments and ecosystems.

5 Must Know Facts For Your Next Test

1. The Paleogene is divided into three epochs: Paleocene, Eocene, and Oligocene, each representing distinct phases of evolutionary change.
2. After the mass extinction at the end of the Cretaceous, the Paleogene saw a rapid diversification of mammals, with many new species appearing to fill ecological niches left vacant.
3. Floral changes during the Paleogene included the expansion of angiosperms (flowering plants), which became dominant in many ecosystems.
4. The climate during the Paleogene was generally warmer than today, leading to a variety of habitats that supported diverse fauna.
5. Key fossil finds from this period include early primates and marine mammals, providing insight into the evolutionary pathways that shaped present-day species.

Review Questions

• How did the end-Cretaceous extinction impact the evolution of mammals during the Paleogene?
  • The end-Cretaceous extinction opened up numerous ecological niches that were previously occupied by dinosaurs. With these dominant reptiles gone, mammals were able to diversify rapidly during the Paleogene, leading to the emergence of various forms adapted to different environments. This allowed for significant evolutionary innovations, including larger body sizes and more complex behaviors among early mammals.
• Discuss the major climatic conditions of the Paleogene period and how they influenced terrestrial environments.
  • During the Paleogene, the climate was generally warmer than it is today, which significantly influenced terrestrial environments. The warmth promoted lush vegetation, including extensive forests that supported diverse ecosystems. These conditions favored the diversification of both flora and fauna, allowing many modern mammal and bird families to evolve and thrive in varied habitats across continents.
• Evaluate the significance of floral changes during the Paleogene in relation to mammalian evolution.
  • Floral changes during the Paleogene were crucial for mammalian evolution because they provided new food sources and habitats. The rise of angiosperms allowed for a broader range of dietary options for herbivorous mammals, which in turn influenced predator-prey dynamics and ecosystem structure. The resulting diversity in plant life also supported various mammalian adaptations, leading to innovations such as specialized teeth and foraging behaviors that have shaped modern ecosystems.

Related terms

Paleocene: The first epoch of the Paleogene period, lasting from about 66 to 56 million years ago, known for the emergence of early mammals and the recovery of life following the Cretaceous-Paleogene extinction event.

Eocene: The second epoch of the Paleogene, spanning from about 56 to 34 million years ago, during which mammals and birds continued to diversify and many modern families began to appear.

Oligocene: The third epoch of the Paleogene, lasting from about 34 to 23 million years ago, marked by further evolution of mammals and significant climatic changes that influenced terrestrial environments.