The fossils found at Dinosaur Park inform our understanding of a relatively unknown time in Earth’s history called the early Cretaceous Period (about 110 million years ago). In many ways, the Early Cretaceous marked the birth of modern world. In North America, the previously hot and tropical climate became cooler and drier, with pronounced seasons. Meanwhile, flowering plants first became widespread during the Cretaceous, replacing ancient fern and conifer forests and irrevocably transforming the ecosystem. Fossilized remains of plants and animals from Dinosaur Park help us understand how and why these major environmental transitions took place. They may even help us predict how our world will respond to climate change in the future.
Plant fossils are especially important because they are reliable indicators of climate and environment. The environmental tolerances of modern plants (such as preferred temperature, annual rainfall, and soil acidity) give paleontologists a good idea of what the ancient environment was like when we find their fossil relatives.
We can also compare the plant communities in fossil deposits of different ages to learn how the Earth’s climate has changed over time. At Dinosaur Park, we find abundant wood and cones from conifer trees, especially cypress. Today, cypress trees are common in lowland swamps throughout the southeast United States. These trees are well-adapted for life in waterlogged, swampy soil. In addition to their rot-resistant wood, their knees (woody extensions of the roots) help to stabilize the trees in soft ground.
Animal fossils also hold clues about prehistoric climate. For example, some of the most common finds at Dinosaur Park are crocodile teeth and armor fragments. Crocodiles are endothermic (“cold-blooded”), meaning that their body temperature is dependent on the air around them. This means that crocodiles can only live in areas without long periods of freezing temperatures. Since crocodiles were plentiful in ancient Maryland, the climate must have been warm and subtropical, similar to southern Louisiana or the Florida everglades today.
Taken together, the fossils found at Dinosaur Park indicate that central Maryland was warm, wet, and swampy during the early Cretaceous. Swimsuits, anyone?