SUBAQUEOUS AVIAN NEOICHNOLOGY: USING DOMESTIC CHICKENS (GALLUS GALLUS DOMESTICUS) AS MODERN ANALOGS FOR DINOSAUR TRACK PRODUCTION AND PRESERVATION

Most neoichnological trackway experiments with terrestrial vertebrates focus on subaerially exposed substrates, and while these experiments may consider preservational differences caused by varying moisture content, little attention has been given to modern traces produced by the locomotion of these animals across sediments that are completely submerged under water. We consider a spectrum from walking to swimming that may help, for example, with interpretation of fossil swim tracks attributed to dinosaurs. Research was conducted at the Bottle Tree Poultry Farm in Holly Springs, Mississippi in which domestic chickens (Gallus gallus domesticus) were observed to assess track production in a subaqueous, water-saturated substrate. A 2 x 0.5 m wood box was constructed and filled with different proportions of sand and water to provide a medium for the chickens to walk across. Substrate slope angle was also varied to simulate shores with different relief. A corridor was created with metal fencing for walls and a wooden board for a roof, to restrict locomotion to the experimental substrate. One chicken at a time was allowed to walk through the substrate from one end of the box to the other and was filmed during the process. After a chicken completed the walk, the tracks it left behind were photographed. Preliminary results show that subaqueous walking tracks are poorly formed, but individual digit impressions are still recognizable on the surface. Subsurface substrate deformation is also very distinct when viewed in cross section. By studying chickens’ interactions with water-saturated sand, we can observe fine details in the substrate to better recognize and interpret fossil tracks and traces attributed to shorebirds and swimming dinosaurs. This study can also help us more fully understand the morphology of swim tracks and the associated behavior of dinosaurs in semi-aquatic and aquatic settings as well as the depositional environment in which the tracks were produced.