Ancient Trackway - United States

United States

In the United States, dinosaur footprints and trackways are found in the Glen Rose Formation, the most famous of these being the Paluxy River site in Dinosaur Valley State Park. These were the first sauropoda footprints scientifically documented, and were designated a US National Natural Landmark in 1969. Some are as large as about 3 feet across. The prints are thought to have been preserved originally in a tidal flat or a lagoon. There are tracks from two types of dinosaur. The first type of tracks are from a sauropoda and were made by an animal of 30 to 50 feet in length, perhaps a brachiosaurid such as Pleurocoelus, and the second tracks by a theropoda, an animal of 20 to 30 feet in length, perhaps an Acrocanthosaurus. A variety of scenarios was proposed to explain the tracks, but most likely represent twelve sauropods "probably as a herd, followed somewhat later by three theropods that may or may not have been stalking -- but that certainly were not attacking."

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