The Mesozoic Era, often recognized as the “Age of Dinosaurs,” spanned approximately 252 to 66 million years ago, encompassing the Triassic, Jurassic, and Cretaceous periods. Earth’s plant life underwent profound changes throughout this era, evolving from ancient, non-flowering forms to the eventual emergence of diverse flowering plants. The vegetation during the dinosaurs’ reign was strikingly different from today’s landscapes, reflecting a long history of botanical evolution.
Giants of the Ancient Forests
During the early and mid-Mesozoic Era, conifers emerged as the predominant tree types, forming vast forests across the globe. These cone-bearing trees, many evergreen, resembled modern pines, spruces, and firs. Ancient relatives of today’s sequoia and araucaria (monkey puzzle tree) were widespread, with some araucaria species reaching 100 meters (328 feet) tall.
These towering conifers provided extensive habitats and a primary food source for many herbivorous dinosaurs. Fossil evidence indicates araucaria forests were abundant globally during the Jurassic and Cretaceous periods, shaping the landscape through which dinosaurs roamed.
Living Fossils and Palm-like Plants
Beyond the dominant conifers, other distinctive seed-bearing plants coexisted with dinosaurs, including ginkgoes and cycads. Ginkgoes are often referred to as “living fossils” because their form has changed little over millions of years; the modern Ginkgo biloba is the sole surviving species of a once diverse group. Fossil ginkgo leaves from the Jurassic period are nearly identical to those found today, demonstrating their remarkable evolutionary stability.
Cycads, with their stout trunks and large, stiff leaves, bore a superficial resemblance to palms and were widespread during the Mesozoic. The Mesozoic Era is sometimes called the “Age of Cycads” due to their abundance and diversity, particularly during the Triassic and Jurassic periods when they comprised up to 20% of the world’s flora. These plants were an important part of the dinosaur diet and habitat.
Lush Undergrowth and Groundcover
Beneath the towering trees, a diverse array of non-seed-bearing plants formed the undergrowth and groundcover of dinosaur-era forests. Ferns, horsetails, and clubmosses, all ancient lineages, thrived in damp and shaded environments. These plants reproduce via spores rather than seeds or flowers.
Many modern ferns diversified during the Mesozoic, and horsetails, represented today by the genus Equisetum, also appeared in the Triassic. These low-growing plants contributed significantly to the ecosystem, providing food and shelter for smaller dinosaurs and other creatures. Their presence added to the rich biodiversity of the lower canopy in these ancient forests.
The Arrival of Modern Flora
Towards the end of the Mesozoic Era, particularly during the Cretaceous period, flowering plants, known as angiosperms, began to emerge and diversify. These new plants introduced features like flowers, fruits, and deciduous leaves, gradually transforming the global landscape. Angiosperms evolved rapidly, with molecular evidence suggesting that many modern flowering plant families existed before the mass extinction event that ended the Cretaceous period.
The rise of angiosperms represented a fundamental shift in plant reproductive strategies. Many developed colorful flowers and fruits to attract animal pollinators and seed dispersers, including some dinosaurs. This changed ancient ecosystems, leading to the replacement of many gymnosperms and ferns in dominant ecological roles over time. The success of these adaptable plants set the stage for the flora that would become prevalent after the age of dinosaurs.