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Mar 28

Trees and Climate

Posted on March 28, 2018 at 3:11 PM by Bonnie Man

frog in water illustrationThe image here is a small section from a large mural of prehistoric Maryland, which is currently being prepared by local artist Clarence Schumaker. We are planning to unveil the completed artwork at Dinosaur Park later this year.

Aside from the charming little frog, the most prominent organism in this image is a cypress tree – specifically its characteristic “knees.” Today, bald cypress trees are common in lowland swamps throughout the southeast United States. These trees are well-adapted to life in waterlogged, swampy soil. In addition to their rot-resistant wood, the knees (actually woody extensions of the roots) help to stabilize the tree in soft ground.

We know that bald cypress trees grew in prehistoric Maryland because we find their fossils. In fact, the tiny, globular cones (think pinecones) of bald cypress trees are some of the most common fossils at Dinosaur Park. During Saturday Open Houses, visitors typically find many cones over the course of the afternoon. Unlike animal fossils, which can be found complete and intact, plant fossils are virtually always found in pieces. Different conditions are needed to fossilize the trunk or the leaves or the cones of a tree, and it is rare to find all of these parts in one place. At Dinosaur Park, the very fine clay is well-suited for preserving cones, or more often, their impressions. This is fortunate, because cones are easy to identify. Many kinds of wood look the same, but different conifer trees produce differently shaped cones. In this case, the tiny, honeycomb-like cones found at the park are characteristic of bald cypress trees.

Plant fossils are important because they are reliable indicators of climate and environment. There is an obvious reason for this: animals move around, but plants can be trusted to stay put in an area that suits their needs. The environmental tolerances of modern plants (temperature, annual rainfall, soil acidity and stability) 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, the plentiful bald cypress cones are one of many lines of evidence that central Maryland was warm, wet, and swampy in the Early Cretaceous Period. Swimsuits, anyone?