The Remarkable Legacy of the Tertiary Period: Unveiling Earth’s Transformation

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The Tertiary Period, also known as the Cenozoic Era, is a major division of Earth’s geologic history. It covers a vast time span from approximately 65 million to 2.6 million years ago, following the extinction of the dinosaurs and the end of the Mesozoic Era. The Tertiary is characterized by remarkable geological and biological changes, including the emergence and diversification of many modern plant and animal groups. In this article, we will explore the major highlights and scientific significance of the Tertiary Period.

1. Climate and environmental changes

During the Tertiary Period, Earth experienced significant climatic and environmental changes. The epoch began with a warm climate, a transition from the greenhouse conditions of the preceding Cretaceous period. However, as the Tertiary progressed, the planet gradually cooled, with fluctuating periods of warmth and ice ages. These climatic variations influenced the distribution of flora and fauna, leading to the development of diverse ecosystems across the globe.

One of the most notable events of the Tertiary period was the formation of the Antarctic ice sheet. Approximately 34 million years ago, Antarctica was largely glaciated, resulting in a significant drop in global sea level. This glaciation significantly affected ocean currents, atmospheric circulation patterns, and global climate dynamics. The cooling trend continued, culminating in the ice ages of the subsequent Quaternary period.

2. Evolution and radiation of mammals

The Tertiary Period witnessed a remarkable radiation and diversification of mammals. After the extinction of the dinosaurs, mammals gradually emerged as the dominant terrestrial vertebrates. They diversified into different ecological niches and evolved adaptations that allowed them to exploit different habitats and food sources.

One of the iconic groups of mammals that emerged during the Tertiary Period is the order Primates, which includes humans, apes, monkeys, and prosimians. The early primates underwent significant evolutionary changes, developing features such as grasping hands, stereoscopic vision, and increased brain size. These adaptations were critical to their arboreal lifestyle and the subsequent evolution of more complex social behaviors.

The Tertiary also witnessed the evolution of several other mammalian groups, including carnivores, ungulates, rodents, and cetaceans. Many of the modern families and genera of mammals that we see today originated during this period. The rich fossil record of the Tertiary provides valuable insights into the evolutionary history and relationships of these groups.

3. Plant Evolution and the Rise of Angiosperms

The Tertiary Period witnessed significant advances in plant evolution, particularly with the rise of angiosperms, or flowering plants. Angiosperms diversified rapidly and became the dominant group of plants during this time. They developed a wide range of reproductive strategies, including flowers and fruits, which played a crucial role in their successful colonization of different habitats.

The emergence of angiosperms brought about significant changes in terrestrial ecosystems. The evolution of flowers facilitated more efficient pollination mechanisms, leading to increased reproductive success. The development of fruits allowed seed dispersal by animals, contributing to the establishment of diverse plant communities.

The Tertiary also saw the expansion of grasslands, which had a profound effect on the ecology and evolution of many plant and animal species. Grasses became more abundant, leading to the emergence of grazers such as horses, antelopes, and elephants. This shift in vegetation types and the associated adaptations influenced the evolutionary trajectories of numerous organisms.

4. Impact events and mass extinctions

The Tertiary Period witnessed a series of impacts and mass extinctions that shaped the course of evolution. The most notable event was the Chicxulub impact, which occurred about 66 million years ago at the boundary between the Cretaceous and Tertiary periods. This cataclysmic event, caused by a massive asteroid or comet, led to the extinction of the dinosaurs and numerous other species, creating an ecological void that allowed the diversification of mammals and other groups.

While the Chicxulub impact is the most famous, other impact events during the Tertiary Period also had significant consequences. These events, although less catastrophic, caused regional extinctions and ecosystem disruptions. However, they also provided opportunities for surviving species to adapt and evolve, leading to new ecological interactions and the eventual formation of modern ecosystems.

5. Human origins and early hominins

The Tertiary is of great importance for understanding human origins and the evolutionary history of early hominins. While the emergence of anatomically modern humans (Homo sapiens) occurred much later, during the Quaternary Period, the Tertiary lays the foundation for our understanding of primate evolution and the development of traits that distinguish us from other animals.

The Tertiary fossil record provides critical insights into the early stages of primate evolution, including the divergence of the primate lineage from other mammals, the development of arboreal adaptations, and the emergence of early hominins. Fossil discoveries such as Ardipithecus, Australopithecus, and early members of the genus Homo shed light on the anatomical and behavioral changes that occurred during this time.

The Tertiary witnessed the transition from more ape-like primates to hominins with increased bipedalism, tool use, and expanded cognitive abilities. While the full story of human evolution extends beyond the Tertiary, this period provides critical insights into the early stages of our evolutionary journey.


The Tertiary is a pivotal chapter in Earth’s history, marked by significant environmental changes, the radiation of mammals, the rise of angiosperms, impact events, and the emergence of early hominins. The rich fossil record and geological evidence have allowed scientists to unravel the intricate tapestry of life’s evolution during this time. By studying the Tertiary, we gain valuable insights into the origins and evolution of diverse ecosystems and the remarkable adaptations that shaped the world we live in today.


What is the Tertiary period known for?

The Tertiary period is known for several significant geological and biological events that shaped the Earth’s history.

When did the Tertiary period occur?

The Tertiary period occurred from approximately 66 million to 2.6 million years ago, following the extinction of dinosaurs and the end of the Cretaceous period.

What major geological changes took place during the Tertiary period?

During the Tertiary period, there were significant geological changes, including the uplifting of mountain ranges such as the Himalayas and the Andes, as well as the formation of many modern-day landforms and geological features.

What were some notable biological developments during the Tertiary period?

The Tertiary period was marked by the diversification and evolution of many modern groups of plants and animals. Mammals, in particular, experienced a significant adaptive radiation and became the dominant land animals.

What were some notable prehistoric mammals that existed during the Tertiary period?

Some notable prehistoric mammals that emerged during the Tertiary period include large herbivores like the Indricotherium and Andrewsarchus, as well as carnivorous mammals like the saber-toothed cats and early ancestors of whales.