Paleontologist Roland T. Bird first excavated fossilized tracks along the Paluxy River in Texas in 1940. The tracks belong to a theropod and sauropod that lived 110 million years ago, and appear to be the remains of an ancient chase. Bird documented the scene 45-meter-long (147 ft) scene with 17 photographs, and then the actual fossils were sectioned off and sent around the world. A new paper by Peter Falkingham of the Royal Veterinary College and his colleagues have now made 3D reconstructions of the scene based off of those photographs. The full report has been published in PLOS ONE.
When Bird first analyzed the scene nearly 75 years ago, he noted that some of the theropod tracks overlapped the sauropod tracks, which made it look like the theropod came soon after. Theropods are a primarily carnivorous clade of dinosaurs that are the ancestors of modern birds and some famous genera in the theropod suborder include Tyrannosaurus and Velociraptor. Herbivorous sauropods have long necks and long tails, and include Brachiosaurus and Apatosaurus.
Though some sections of the site were transported to educational institutions, others have been irrevocably lost over the years, with only Bird’s analysis and photographs to represent the entire site.
Falkingham’s study scanned the photographs and combined them in order to have a cohesive image of the entire scene. Through photogrammetry, the researchers were able to construct a 3D computer image of the original site. Shading on the tracks gave information about the depth of the tracks, though not all of the photographs yielded the same clarity. With that information, scientists can now make replicas of the chase scene using a 3D printer. This technique could open the door for other studies where the physical object is lost, but clear photographs remain.
Paul Barrett of London’s Natural History Museum told BBC News that Falkingham’s work was part of a “neat study.” "It has allowed the [team] to recover important data previously thought to be irrevocably lost," he continued. "These dinosaur track sites are of major historical importance, and being able to retrieve this level of information 70 years after they were broken up and dispersed is a nice outcome."
FIGURE 1: Sixteen of Bird's original photographs used in the photogrammetric reconstruction of the trackway. Note that the state of excavation (flooded parallel trackways, sandbags, tools etc) varies between images, causing complications for the reconstruction. doi:10.1371/journal.pone.0093247.g001