Flowering plants dominate much of the natural world, from tropical rainforests and open grasslands to gardens and agricultural fields. Scientists have long wondered how these plants became so widespread while many ancient competitors declined.

New research suggests that dramatic climate changes millions of years ago played a central role in this transformation.

A study published in Nature Plants in October 2026 found that two exceptionally warm periods in Earth's history coincided with major changes in plant diversity, including widespread extinctions and the emergence of new species.

The findings offer fresh insight into the evolution of modern ecosystems and raise important questions about the consequences of today's rapidly warming climate.

How Flowering Plants Became Dominant

Flowering plants, also known as angiosperms, include approximately 400,000 species worldwide. They provide food, shelter and other essential resources for countless animals, fungi and microorganisms. However, flowering plants have not always dominated Earth's landscapes.

Around 100 million years ago, during the Cretaceous Period, they began replacing older plant groups that had flourished for hundreds of millions of years.

Scientists have proposed several explanations for their success, including evolutionary innovations and changing environmental conditions. Until recently, determining the precise influence of climate remained difficult because the fossil record contains significant gaps.

What Ancient Fossils Revealed

Researchers from Australia and Austria examined more than 60,000 fossil occurrences, focusing on preserved pollen and spores. These microscopic remains provide valuable information about plants that existed millions of years ago. Unlike larger plant fossils, pollen and spores can survive in sedimentary deposits and offer evidence of ancient vegetation.

The team used statistical methods designed to reduce biases caused by differences in fossil availability across regions and geological periods. This allowed researchers to reconstruct changes in plant diversity across approximately 130 million years. Their analysis identified two major periods of evolutionary transformation.

Extreme Heat Reshaped Plant Life

The most dramatic changes occurred during exceptionally warm intervals in the middle of the Cretaceous Period and the early Cenozoic Era. During these periods, numerous plant groups disappeared while new, evolutionarily related groups emerged.

Researchers found that both extinction and diversification were strongly associated with extreme global warmth. These transformations unfolded over several million years. By comparison, cooler periods generally experienced relatively little change in plant diversity. Other possible explanations, including geographical separation and competition between plant groups, showed weaker relationships with the observed patterns.

Why The Findings Matter Today

The research suggests that climate has been an important influence on the development of terrestrial biodiversity. However, scientists caution against assuming that modern global warming will eventually produce similar benefits.

Ancient warming episodes occurred over geological timescales, giving evolutionary processes millions of years to unfold. Today's human-driven temperature increases are happening considerably faster.

Chris Mays, a palaeontologist at Vienna's Natural History Museum and a co-author of the study, warns that contemporary warming could cause plant extinctions much more rapidly than past climate changes.

Even if new species eventually evolve, replacing lost biodiversity could take millions of years.

Protecting The Diversity Of Plants

Plants support nearly every terrestrial ecosystem by capturing solar energy, absorbing carbon dioxide and providing resources for other organisms.

Losing plant diversity could therefore affect food chains, habitats and essential ecological relationships.

The study demonstrates that periods of extreme heat have repeatedly transformed life on Earth, but these changes often involved substantial biological losses.

Its message is particularly relevant today: understanding how ancient climates shaped biodiversity can help scientists appreciate the risks facing modern ecosystems.

Protecting existing species remains far more practical than relying on evolution to replace them in the distant future.