Back in 1940, paleontologist Roland T. Bird hypothesized that the largest animals ever living on Earth, despite having four legs, moved mainly on two front (manus), not using hind (pes). The basis for this assumption was found in Bandera County, Texas, footprints of fossil creatures.
According to the researcher, at least during swimming, sauropods used only their forelimbs for movement. A similar method could be applied when moving on land, but then it was believed that the manus accounts for the bulk of the body of dinosaurs, therefore pes leave shallow traces that are simply erased over time.
Byrd's hypothesis is revisited today when, in 2007, numerous dinosaur footprints were found in the Coffee Hollow limestone quarry, which is part of the Glen Rose Formation in Texas, dating from roughly 110 million years ago. Teams of researchers from Purdue University in Fort Wayne and the Houston Museum of Natural Sciences studied several dozen sauropod footprints that make up three separate paths of movement.
Paleontologists, after analyzing the 70-centimeter tracks, came to the conclusion that they were left by the front legs of sauropods. In an article published in the journal Ichnos, scientists note that at least in some situations, giant dinosaurs really walked only on two front legs - they used this method to overcome water obstacles, leaving their hind legs in weight. But it is possible that on a hard surface in some situations that are still to be clarified, sauropods moved exclusively with the help of the manus.