Tracing the Origins of Oaks: How Climate and Tectonic Changes Shaped Modern Trees

Rising global temperatures and shifting tectonic plates are believed to have shaped the development of one of Earth’s most iconic trees, the oak (Quercus).

According to reports, the Paleocene-Eocene Thermal Maximum (PETM), a significant climatic event approximately 56 million years ago, created extreme conditions that influenced the evolution of diverse plant species, including the ancestors of modern oaks. This event occurred during a time of volcanic activity that released massive amounts of carbon into the atmosphere, leading to an average temperature increase of 8 degrees Celsius globally.

The Impact of the PETM on Early Ecosystems
It has been documented that the PETM caused dramatic changes in both terrestrial and marine ecosystems. According to sources, tropical forests expanded across South America, while plant and animal species migrated vast distances in response to rising temperatures. The fossil record suggests that during this period, the ancestors of today’s oaks began to emerge, though evidence such as acorns and pollen remains sparse.

First Oak Fossils Discovered in Austria
Fossilised oak pollen was first identified in Oberndorf, Austria, near the site of the Church of Saint Pankraz. Reports indicate that this discovery provides the earliest evidence of oaks dating back to the PETM. The surrounding forests, a mosaic of subtropical and temperate species, were home to plants that later contributed to modern biodiversity.

The Evolutionary Split of Oaks
As the Atlantic Ocean widened, dividing North America and Europe, reports suggest that the ancestral oak population split into two major lineages. One evolved in the Americas, while the other adapted to regions in Eurasia and North Africa. This separation is attributed to tectonic activity and natural barriers, which likely played a critical role in the diversification of oak species. The history of oaks exemplifies the gradual process of evolution driven by environmental factors, with their legacy continuing into today’s temperate forests.