Diggin' For Dinosaurs - Dinosaur Valley
The most famous are the tracks left by Pleurocoelus, a 20-ton example of the long-necked vegetarian dinosaurs known as sauropods. Its footprints, round and blobby, are as big as washtubs. The most common tracks are the pointy, three-toed type left behind by a two-legged carnivore, or theropod. These were most likely made by Acrocanthosaurus, an early and smaller relative of Tyrannosaurus rex that still measured an impressive 30 feet long. The most curious tracks at Glen Rose are wider and more rounded versions of a three-toed print. They may have been left behind by Iguanodon, a two-legged plant eater whose bones were discovered in Texas in 1985.
Around 110 million years ago, the Glen Rose area was a muddy tidal flat, at the edge of a shallow sea that spread and then shrank across central North America for millions of years. The wide flats, framed by bushes and trees, would have made a perfect place for sauropods to browse while theropods stalked.
Local moonshiners and fishermen were the first to know of the mighty tracks left behind by these creatures. In fact, one of the theropod footprints was built into the bandstand at the Somervell County courthouse in Glen Rose. Palaeontologists didn't learn about the tracks until the early part of this century, when geologists discovered the three-toed theropod prints. Building on the area's reputation, locals began carving fake prints into other chunks of rock and selling them during the Great Depression. Although they were never intended to deceive scientists, the Glen Rose carvings nevertheless initiated decades of misinterpretation of the Paluxy River trackways.
One of the fakes, however, did put Glen Rose on the map for palaeontologists. In 1938, fossil-hunter Roland T. Bird was shown one of the carvings in New Mexico while looking for treasures to bring back to his bosses at the American Museum of Natural History in New York. He knew the carving was fake but immediately set out for Glen Rose, where the rock came from, to check out tales of other dinosaur trackways.
Once at the Paluxy, Bird found the real theropod tracks. And then came the big discovery - tracks of at least a dozen sauropods in the riverbed. He contracted for a crew from the Works Progress Administration, diverted the river, chipped out huge sections of trackway, and shipped them back to New York to be reassembled. Today the footprints can be seen at the American Museum of Natural History, while other chunks are at other museums, including the Texas Memorial Museum at the University of Texas in Austin.
At the Paluxy trackway itself, palaeontologists still don't agree on Bird's suggestion that the intermingled tracks of sauropods and thero-pods represent a deadly hunt. At first glance, the evidence seems good. A herd of a dozen sauropods left tracks, followed roughly parallel by the prints of four theropods. One of the theropod's tracks seems to curve into the trail of a sauropod. Indeed, the theropod track has one step missing, as if the carnivore lunged at the other dinosaur's neck, grabbed on with its teeth, and was carried along for one step in a deadly embrace.