Paleogene

Definition

The Paleogene is a geological period that lasted from about 66 million to 23 million years ago, marking the beginning of the Cenozoic Era. It follows the mass extinction event at the end of the Cretaceous period and is significant for the rapid evolution and diversification of mammals and birds, which began to occupy ecological niches left vacant by the extinction of dinosaurs.

5 Must Know Facts For Your Next Test

1. The Paleogene is divided into three epochs: Paleocene, Eocene, and Oligocene, each marked by distinct climatic conditions and evolutionary developments.
2. During the Paleogene, global temperatures were generally warmer than today, with tropical forests extending much further north than they do now.
3. This period saw the emergence of early primates and the diversification of flowering plants, which played a critical role in shaping modern ecosystems.
4. The Paleogene also witnessed significant geological changes, including the formation of mountain ranges like the Himalayas due to tectonic activity.
5. The extinction of large reptiles created opportunities for mammals to evolve and fill ecological roles previously held by dinosaurs, leading to their dominance in later periods.

Review Questions

• How did the end of the Cretaceous mass extinction influence mammalian evolution during the Paleogene?
  • The mass extinction at the end of the Cretaceous opened up numerous ecological niches for mammals due to the decline of dinosaurs. This led to a rapid diversification of mammals during the Paleogene as they adapted to various environments. With less competition from large reptiles, mammals evolved into different sizes and forms, filling roles in terrestrial ecosystems that had been vacated.
• Discuss the climatic conditions during the Paleogene and their impact on terrestrial ecosystems.
  • The Paleogene was characterized by generally warmer global temperatures compared to today. This climate allowed for lush tropical forests and diverse flora and fauna to flourish. The warm conditions contributed to a rich ecosystem where early primates began to evolve, along with a wide variety of flowering plants that provided food sources for newly diversified animal populations.
• Evaluate how geological changes during the Paleogene contributed to evolutionary trends observed in this period.
  • Geological changes such as tectonic shifts during the Paleogene significantly influenced evolutionary trends by altering habitats and climate patterns. For instance, the formation of mountain ranges affected weather patterns and created barriers that isolated populations, leading to speciation. These geological transformations played a crucial role in shaping ecosystems and facilitating the evolutionary pathways that allowed mammals and birds to thrive in diverse environments.

Related terms

Cenozoic Era:

The current geological era that began 66 million years ago, encompassing the Paleogene, Neogene, and Quaternary periods, characterized by the dominance of mammals and birds.

Mass Extinction: A significant and rapid decrease in biodiversity on Earth, often due to catastrophic events; the most notable mass extinction at the end of the Cretaceous wiped out approximately 75% of all species.

Paleoclimatology:

The study of ancient climates, which helps scientists understand how climate changes influenced the evolution of life during periods such as the Paleogene.