How Dinosaur Tracks are Preserved
© 2010, Robert E. Gentet
Track preservation can be a tricky thing. We are all aware that our tracks made along a beach aren’t normally preserved. The first wave usually destroys them. How, then, can the preservation of dinosaur tracks be understood? Obviously, the process demands something different from our everyday experience along a beach.
While the answer is not totally clear, several factors are important. Tracks made on surfaces exposed to the sun will harden the wet sediment. Mud cracks are found at some footprint sites indicating a brief time of drying. The exact chemical composition of the surface material is also important. The chemical makeup of the material is a factor in its chances of preservation.
In the case of large dinosaur prints, the huge weight of the dinosaur will impress the footprint below the surface onto the underlying layers. These prints made below the surface layer are more protected and subsequent erosion on the topmost layer poses a smaller threat to the under prints. Small dinosaur tracks are more rare than large ones, probably for this reason.
Tracks tend to accumulate additional sediment more readily than the surrounding ground. This additional sediment can protect delicate footprint features. This is shown at Dinosaur State Park in Connecticut where large dinosaur tracks show rare skin impressions. Yet, the area between the Connecticut tracks is scoured by erosion. Early observers of the tracks at the Glen Rose, Texas, site also reported seeing skin impressions. The protection afforded by the early accumulation of sediment in the tracks is important.
This page is a subtopic of When Dinosaurs Roamed Texas.